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updated Sat Mar 27 2021 by Robert van Engelen
 
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1 
2 C and C++ XML Data Bindings {#mainpage}
3 ===========================
4 
5 [TOC]
6 
7 Introduction {#intro}
8 ============
9 
10 This article presents a detailed overview of the gSOAP XML data bindings for C
11 and C++. The XML data bindings for C and C++ are extensively used with gSOAP
12 Web services to serialize C and C++ data in XML as part of the SOAP/XML Web
13 services payloads. Also REST XML with gSOAP relies on XML serialization of C
14 and C++ data via XML data bindings.
15 
16 The major advantage of XML data bindings is that your application data is
17 always **type safe** in C and C++ by binding XML schema types to C/C++ types.
18 So integers in XML are bound to C integers, strings in XML are bound to C or
19 C++ strings, complex types in XML are bound to C structs or C++ classes, and so
20 on. The structured data you create and accept will fit the data model and is
21 **static type safe**. In other words, by leveraging strong typing in C/C++,
22 your XML data meets **XML schema validation requirements** and satisfies **XML
23 interoperability requirements**.
24 
25 In fact, gSOAP data bindings are more powerful than simply representing C/C++
26 data in XML. The gSOAP tools implement true and tested **structure-preserving
27 serialization** of C/C++ data in XML, including the serialization of cyclic
28 graph structures with id-ref XML attributes. The gSOAP tools also generate
29 routines for deep copying and deep deletion of C/C++ data structures to
30 simplify memory management. In addition, C/C++ structures are deserialized
31 into managed memory, managed by the gSOAP `soap` context.
32 
33 At the end of this article two examples are given to illustrate the application
34 of XML data bindings. The first simple example <i>`address.cpp`</i> shows how to use
35 wsdl2h to bind an XML schema to C++. The C++ application reads and writes an
36 XML file into and from a C++ "address book" data structure as a simple example.
37 The C++ data structure is an STL vector of address objects. The second example
38 <i>`graph.cpp`</i> shows how C++ data can be accurately serialized as a tree, digraph,
39 and cyclic graph in XML. The digraph and cyclic graph serialization rules
40 implement SOAP 1.1/1.2 multi-ref encoding with id-ref attributes to link
41 elements through IDREF XML references, creating a an XML graph with pointers to
42 XML nodes that preserves the structural integrity of the serialized C++ data.
43 
44 These examples demonstrate XML data bindings only for relatively simple data
45 structures and types. The gSOAP tools support more than just these type of
46 structures to serialize in XML. There are practically no limits to the
47 serialization of C and C++ data types in XML.
48 
49 Also the support for XML schema (XSD) components is unlimited. The wsdl2h tool
50 maps schemas to C and C++ using built-in intuitive mapping rules, while
51 allowing the mappings to be customized using a <i>`typemap.dat`</i> file with mapping
52 instructions for wsdl2h.
53 
54 The information in this article is applicable to gSOAP 2.8.26 and greater that
55 support C++11 features. However, C++11 is not required. The material and the
56 examples in this article use plain C and C++, until the point where we
57 introduce C++11 smart pointers and scoped enumerations. While most of the
58 examples in this article are given in C++, the concepts also apply to C with
59 the exception of containers, smart pointers, classes and their methods. None
60 of these exceptions limit the use of the gSOAP tools for C in any way.
61 
62 The data binding concepts described in this article were first envisioned in
63 1999 by Prof. Robert van Engelen at the Florida State University. An
64 implementation was created in 2000, named "stub/skeleton compiler". The first
65 articles on its successor version "gSOAP" appeared in 2002. The principle of
66 mapping XSD components to C/C++ types and vice versa is now widely adopted in
67 systems and programming languages, including Java web services and by C# WCF.
68 
69 We continue to be committed to our goal to empower C/C++ developers with
70 powerful autocoding tools for XML. Our commitment started in the very early
71 days of SOAP by actively participating in
72 [SOAP interoperability testing](http://www.whitemesa.com/interop.htm),
73 participating in the development and testing of the
74 [W3C XML Schema Patterns for Databinding Interoperability](http://www.w3.org/2002/ws/databinding),
75 and continues by contributing to the development of
76 [OASIS open standards](https://www.oasis-open.org) in partnership with leading
77 IT companies in the world.
78 
79 🔝 [Back to table of contents](#)
80 
81 Notational Conventions {#conventions}
82 ======================
83 
84 The typographical conventions used by this document are:
85 
86 * `Courier` denotes C and C++ source code.
87 
88 * <i>`Courier`</i> denotes XML content, JSON content, file and path names, and URIs.
89 
90 * <b>`Courier`</b> denotes HTTP content, text file content, and shell commands with command line options and arguments.
91 
92 The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD",
93 "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to
94 be interpreted as described in RFC-2119.
95 
96 🔝 [Back to table of contents](#)
97 
98 Mapping WSDL and XML schemas to C/C++ {#tocpp}
99 =====================================
100 
101 To convert WSDL and XML schemas (XSD files) to code, we use the wsdl2h command
102 on the command line (or command prompt), after opening a terminal. The wsdl2h
103 command generates the data binding interface code that is saved to a special
104 Web services and data bindings interface header file with extension <i>`.h`</i>
105 that contains the WSDL service declarations and the data binding interface
106 declarations in a familiar C/C++ format:
107 
108  wsdl2h [options] -o file.h ... XSD and WSDL files ...
109 
110 This command converts WSDL and XSD files to C++ (or pure C with
111 <b>`wsdl2h -c`</b>) and saves the data binding interface to a interface header
112 file <i>`file.h`</i> that uses familiar C/C++ syntax extended with `//gsoap`
113 [directives](#directives) and annotations. Notational conventions are used in
114 the data binding interface to declare serializable C/C++ types and functions
115 for Web service operations.
116 
117 The WSDL 1.1/2.0, SOAP 1.1/1.2, and XSD 1.0/1.1 standards are supported by the
118 gSOAP tools. In addition, the most popular WS specifications are also
119 supported, including WS-Addressing, WS-ReliableMessaging, WS-Discovery,
120 WS-Security, WS-Policy, WS-SecurityPolicy, and WS-SecureConversation.
121 
122 This article focusses mainly on XML data bindings. XML data bindings for C/C++
123 bind XML schema types to C/C++ types. So integers in XML are bound to C
124 integers, strings in XML are bound to C or C++ strings, complex types in XML
125 are bound to C structs or C++ classes, and so on.
126 
127 A data binding is dual, meaning supporting a two way direction for development.
128 Either you start with WSDLs and/or XML schemas that are mapped to equivalent
129 C/C++ types, or you start with C/C++ types that are mapped to XSD types.
130 Either way, the end result is that you can serialize C/C++ types in XML such
131 that your XML is an instance of XML schema(s) and is validated against these
132 schema(s).
133 
134 This covers all of the following standard XSD components with their optional
135 attributes and properties:
136 
137 XSD component | attributes and properties
138 -------------- | -------------------------
139 schema | targetNamespace, version, elementFormDefault, attributeFormDefault, defaultAttributes
140 attribute | name, ref, type, use, default, fixed, form, targetNamespace, wsdl:arrayType
141 element | name, ref, type, default, fixed, form, nillable, abstract, substitutionGroup, minOccurs, maxOccurs, targetNamespace
142 simpleType | name
143 complexType | name, abstract, mixed, defaultAttributesApply
144 all | *n/a*
145 choice | minOccurs, maxOccurs
146 sequence | minOccurs, maxOccurs
147 group | name, ref, minOccurs, maxOccurs
148 attributeGroup | name, ref
149 any | minOccurs, maxOccurs
150 anyAttribute | *n/a*
151 
152 And also the following standard XSD directives are covered:
153 
154 directive | description
155 ---------- | -----------
156 import | Imports a schema into the importing schema for referencing
157 include | Include schema component definitions into a schema
158 override | Override by replacing schema component definitions
159 redefine | Extend or restrict schema component definitions
160 annotation | Annotates a component
161 
162 The XSD facets and their mappings to C/C++ are:
163 
164 XSD facet | maps to
165 -------------- | -------
166 enumeration | `enum`
167 simpleContent | class/struct wrapper with `__item` member
168 complexContent | class/struct
169 list | `enum*` bitmask (`enum*` enumerates a bitmask up to 64 bits)
170 extension | class/struct inheritance/extension
171 restriction | `typedef` and class/struct inheritance/redeclaration
172 length | `typedef` with restricted content length annotation
173 minLength | `typedef` with restricted content length annotation
174 maxLength | `typedef` with restricted content length annotation
175 minInclusive | `typedef` with numerical value range restriction annotation
176 maxInclusive | `typedef` with numerical value range restriction annotation
177 minExclusive | `typedef` with numerical value range restriction annotation
178 maxExclusive | `typedef` with numerical value range restriction annotation
179 precision | `typedef` with pattern annotation (pattern used for output, but input is not validated)
180 scale | `typedef` with pattern annotation (pattern used for output, but input is not validated)
181 totalDigits | `typedef` with pattern annotation (pattern used for output, but input is not validated)
182 fractionDigits | `typedef` with pattern annotation (pattern used for output, but input is not validated)
183 pattern | `typedef` with pattern annotation (define `soap::fsvalidate` callback to validate patterns)
184 union | string with union of value
185 
186 All primitive XSD types are supported, including but not limited to the
187 following XSD types:
188 
189 XSD type | maps to
190 ---------------- | -------
191 any/anyType | `_XML` string with literal XML content (or enable DOM with wsdl2h option `-d`)
192 anyURI | string (i.e. `char*`, `wchar_t*`, `std::string`, `std::wstring`)
193 string | string (i.e. `char*`, `wchar_t*`, `std::string`, `std::wstring`)
194 boolean | `bool` (C++) or `enum xsd__boolean` (C)
195 byte | `char` (i.e. `int8_t`)
196 short | `short` (i.e. `int16_t`)
197 int | `int` (i.e. `int32_t`)
198 long | `LONG64` (i.e. `long long` and `int64_t`)
199 unsignedByte | `unsigned char` (i.e. `uint8_t`)
200 unsignedShort | `unsigned short` (i.e. `uint16_t`)
201 unsignedInt | `unsigned int` (i.e. `uint32_t`)
202 unsignedLong | `ULONG64` (i.e. `unsigned long long` and `uint64_t`)
203 float | `float`
204 double | `double`
205 integer | string or `#import "custom/int128.h"` to use 128 bit `xsd__integer`
206 decimal | string or `#import "custom/long_double.h"` to use `long double`
207 precisionDecimal | string
208 duration | string or `#import "custom/duration.h"` to use 64 bit `xsd__duration`
209 dateTime | `time_t` or `#import "custom/struct_tm.h"` to use `struct tm` for `xsd__dateTime`
210 time | string or `#import "custom/long_time.h"` to use 64 bit `xsd__time`
211 date | string or `#import "custom/struct_tm_date.h"` to use `struct tm` for `xsd__date`
212 hexBinary | special class/struct `xsd__hexBinary`
213 base64Binary | special class/struct `xsd__base64Binary`
214 QName | `_QName` string (URI normalization rules are applied)
215 
216 All other primitive XSD types not listed above are mapped to strings, by
217 wsdl2h generating a `typedef` to string for these types. For example,
218 <i>`xsd:token`</i> is bound to a C++ or C string:
219 
220 ~~~{.cpp}
221  typedef std::string xsd__token; // C++
222  typedef char *xsd__token; // C (wsdl2h option -c)
223 ~~~
224 
225 This associates a compatible value space to the type with the appropriate XSD
226 type name used by the soapcpp2-generated serializers.
227 
228 It is possible to remap types by adding the appropriate mapping rules to
229 <i>`typemap.dat`</i> as we will explain in more detail in the next section.
230 
231 Imported custom serializers are intended to extend the C/C++ type bindings when
232 the default binding to string is not satisfactory to your taste and if the
233 target platform supports these C/C++ types. To add custom serializers to
234 <i>`typemap.dat`</i> for wsdl2h, see [adding custom serializers](#custom) below.
235 
236 🔝 [Back to table of contents](#)
237 
238 Using typemap.dat to customize data bindings {#typemap}
239 ============================================
240 
241 Use a <i>`typemap.dat`</i> file to redefine namespace prefixes and to customize type
242 bindings for the the generated header files produced by the wsdl2h tool. The
243 <i>`typemap.dat`</i> is the default file processed by wsdl2h. Use <b>`wsdl2h -tfile.dat`</b>
244 option <b>`-tfile.dat`</b> to specify a different mapping file <i>`file.dat`</i>.
245 
246 Declarations in <i>`typemap.dat`</i> can be broken up over multiple lines by
247 continuing on the next line by ending each line to be continued with a
248 backslash <b>`\`</b>. The limit is 4095 characters per line, whether the line is
249 broken up or not.
250 
251 🔝 [Back to table of contents](#)
252 
253 XML namespace bindings {#typemap1}
254 ----------------------
255 
256 The wsdl2h tool generates C/C++ type declarations that use `ns1`, `ns2`, etc.
257 as schema-binding URI prefixes. These default prefixes are generated somewhat
258 arbitrarily for each schema targetNamespace URI, meaning that their ordering
259 may change depending on the WSDL and XSD order of processing with wsdl2h.
260 
261 Therefore, it is **strongly recommended** to declare your own prefix for each
262 schema URI in <i>`typemap.dat`</i> to reduce maintaince effort of your code. This
263 is more robust when anticipating possible changes of the schema(s) and/or the
264 binding URI(s) and/or the tooling algorithms.
265 
266 The first and foremost important thing to do is to define prefix-URI bindings
267 for our C/C++ code by adding the following line(s) to our <i>`typemap.dat`</i> or make
268 a copy of this file and add the line(s) that bind our choice of prefix name to
269 each URI:
270 
271  prefix = "URI"
272 
273 For example, to use `g` as a prefix for the "urn:graph" XML namespace:
274 
275  g = "urn:graph"
276 
277 This produces `g__name` C/C++ type names that are bound to the "urn:graph"
278 schema by association of `g` to the generated C/C++ types.
279 
280 This means that <i>`<g:name xmlns:g="urn:graph">`</i> is parsed as an instance of a
281 `g__name` C/C++ type. Also <i>`<x:name xmlns:x="urn:graph">`</i> parses as an
282 instance of `g__name`, because the prefix <i>`x`</i> has the same URI value
283 <i>`urn:graph`</i>. Prefixes in XML have local scopes (like variables in a block).
284 
285 The first run of wsdl2h will reveal the XML namespace URIs, so you do not need
286 to search WSDLs and XSD files for all of the target namespaces. Just copy them
287 from the generated header file after the first run into <i>`typemap.dat`</i> for
288 editing.
289 
290 @note Only define a namespace prefix once in <i>`typemap.dat`</i>. That is, do not
291 use the same prefix for multiple XML namespace URIs. This is to avoid
292 namespace conflicts that may cause failed builds and failures in XML parsing
293 and XML schema validation.
294 
295 🔝 [Back to table of contents](#)
296 
297 XSD type bindings {#typemap2}
298 -----------------
299 
300 Custom C/C++ type bindings can be declared in <i>`typemap.dat`</i> to associate C/C++
301 types with specific schema types. These type bindings have four parts:
302 
303  prefix__type = declaration | use | ptruse
304 
305 where
306 
307 - <b>`prefix__type`</b> is the schema type to be customized (the <b>`prefix__type`</b> name
308  uses the common double underscore naming convention);
309 
310 - <b>`declaration`</b> declares the C/C++ type in the wsdl2h-generated header file.
311  This part can be empty if no explicit declaration is needed;
312 
313 - <b>`use`</b> is an optional part that specifies how the C/C++ type is used in the
314  code. When omitted, it is the same as <b>`prefix__type`</b>;
315 
316 - <b>`ptruse`</b> is an optional part that specifies how the type is used as a pointer
317  type. By default it is the <b>`use`</b> type name with a <b>`*`</b> or C++11
318  <b>`std::shared_ptr<type>`</b> when enabled (see further below). If <b>`use`</b> is already a
319  pointer type by the presence of a <b>`*`</b> in the <b>`use`</b> part, then the default
320  <b>`ptruse`</b> type is the same as the <b>`use`</b> type (that is, no double
321  pointers <b>`**`</b> will be created in this case).
322 
323 For example, to map <i>`xsd:duration`</i> to a `long long` (`LONG64`) type that holds
324 millisecond duration values, we can use the custom serializer declared in
325 <i>`gsoap/custom/duration.h`</i> by adding the following line to <i>`typemap.dat`</i>:
326 
327  xsd__duration = #import "custom/duration.h"
328 
329 Here, we omitted the second and third parts, because `xsd__duration` is the
330 name that wsdl2h uses for this type in our generated code so we should leave
331 the <b>`use`</b> part unspecified. The third part is omitted to let wsdl2h use
332 `xsd__duration *` for pointers or `std::shared_ptr<xsd__duration>` if smart
333 pointers are enabled.
334 
335 To map <i>`xsd:string`</i> to `wchar_t*` wide strings for C source code output:
336 
337  xsd__string = | wchar_t* | wchar_t*
338 
339 For C++ we can use the `std::wstring` wide string:
340 
341  xsd__string = | std::wstring
342 
343 Note that the first part is empty, because these types do not require a
344 declaration. A <b>`ptruse`</b> part is also defined for `wchar_t*`, but this
345 is actually needed because the wsdl2h tool recognizes that the <b>`use`</b>
346 part `wchar_t*` is already a pointer. By contrast, when using 8-bit strings,
347 it is recommended to use the `SOAP_C_UTFSTRING` flag to enable UTF-8 formatted
348 strings.
349 
350 When the auto-generated declaration should be preserved but the <b>`use`</b> or
351 <b>`ptruse`</b> parts replaced, then we use an ellipsis for the declaration part:
352 
353  prefix__type = ... | use | ptruse
354 
355 This is useful to map schema polymorphic types to C types for example, where we
356 need to be able to both handle a base type and its extensions as per schema
357 extensibility. Say we have a base type called <i>`ns:base`</i> that is extended, then
358 we can remap this to a C type that permits referening the extended types via a
359 `void*` as follows:
360 
361  ns__base = ... | int __type_base; void*
362 
363 such that `__type_base` and `void*` will be used to (de)serialize any data
364 type, including base and its derived types. The `__type_base` integer is set
365 to a `SOAP_TYPE_T` value to indicate what type of data the `void*` pointer
366 points to.
367 
368 🔝 [Back to table of contents](#)
369 
370 Custom serializers for XSD types {#custom}
371 --------------------------------
372 
373 In the previous part we saw how a custom serializer is used to bind
374 <i>`xsd:duration`</i> to a `long long` (`LONG64` or `int64_t`) type to store millisecond
375 duration values:
376 
377  xsd__duration = #import "custom/duration.h"
378 
379 The `xsd__duration` type is an alias of `long long` (`LONG64` or `int64_t`).
380 
381 While wsdl2h will use this binding declared in <i>`typemap.dat`</i>
382 automatically, you will also need to compile <i>`gsoap/custom/duration.c`</i>.
383 Each custom serializer has an interface header file to be imported into another
384 interface header file that declares the custom type for soapcpp2 and a
385 serializer implementation file written in C, which should be compiled with the
386 application. You can compile these in C++ (rename files to <i>`.cpp`</i> if
387 needed).
388 
389 A custom serializer is declared in an interface header file for soapcpp2 using
390 `extern typedef`. The typedef name declared is serializable, whereas the
391 type on which it is based is not serializable. This declaration can be
392 combined with `volatile` when the type should not be redeclared, see
393 [volatile classes and structs](#toxsd9-2). For example, the custom serializer
394 for `struct tm` is the type `xsd__datetime` declared as follows in
395 `gsoap/custom/struct_tm.h`:
396 
397 ~~~{.cpp}
398  extern typedef volatile struct tm
399  {
400  int tm_sec; ///< seconds (0 - 60)
401  int tm_min; ///< minutes (0 - 59)
402  int tm_hour; ///< hours (0 - 23)
403  int tm_mday; ///< day of month (1 - 31)
404  int tm_mon; ///< month of year (0 - 11)
405  int tm_year; ///< year - 1900
406  int tm_wday; ///< day of week (Sunday = 0) (NOT USED)
407  int tm_yday; ///< day of year (0 - 365) (NOT USED)
408  int tm_isdst; ///< is summer time in effect?
409  char* tm_zone; ///< abbreviation of timezone (NOT USED)
410  } xsd__dateTime;
411 ~~~
412 
413 Another example is `xsd__duration` as a custom serializer for the C++11 type
414 `std::chrono::nanoseconds`:
415 
416 ~~~{.cpp}
417  extern typedef class std::chrono::nanoseconds xsd__duration;
418 ~~~
419 
420 Next, we present all pre-defined custom serializers that are available to you.
421 
422 🔝 [Back to table of contents](#)
423 
424 ### xsd:integer {#custom-1}
425 
426 The wsdl2h tool maps <i>`xsd:integer`</i> to a string by default. To map <i>`xsd:integer`</i> to
427 the 128 bit big int type `__int128_t`:
428 
429  xsd__integer = #import "custom/int128.h"
430 
431 The `xsd__integer` type is an alias of `__int128_t`.
432 
433 @warning Beware that the <i>`xsd:integer`</i> value space of integers is in principle
434 unbounded and values can be of arbitrary length. A value range fault
435 `SOAP_TYPE` (value exceeds native representation) or `SOAP_LENGTH` (value
436 exceeds range bounds) will be thrown by the deserializer if the value is out of
437 range.
438 
439 Other XSD integer types that are restrictions of <i>`xsd:integer`</i>, are
440 <i>`xsd:nonNegativeInteger`</i> and <i>`xsd:nonPositiveInteger`</i>, which are further restricted
441 by <i>`xsd:positiveInteger`</i> and <i>`xsd:negativeInteger`</i>. To bind these types to
442 `__int128_t` add the following definitions to <i>`typemap.dat`</i>:
443 
444  xsd__nonNegativeInteger = typedef xsd__integer xsd__nonNegativeInteger 0 : ;
445  xsd__nonPositiveInteger = typedef xsd__integer xsd__nonPositiveInteger : 0 ;
446  xsd__positiveInteger = typedef xsd__integer xsd__positiveInteger 1 : ;
447  xsd__negativeInteger = typedef xsd__integer xsd__negativeInteger : -1 ;
448 
449 Or simply uncomment these definitions in <i>`typemap.dat`</i> when you are using the
450 latest gSOAP releases.
451 
452 @note If `__int128_t` 128 bit integers are not supported on your platform and if it
453 is certain that <i>`xsd:integer`</i> values are within 64 bit value bounds for your
454 application's use, then you can map this type to `LONG64`:
455 
456  xsd__integer = typedef LONG64 xsd__integer;
457 
458 @note Again, a value range fault `SOAP_TYPE` or `SOAP_LENGTH` will be thrown by
459 the deserializer if the value is out of range.
460 
461 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/int128.c`</i> with your project.
462 
463 @see Section [numerical types](#toxsd5).
464 
465 🔝 [Back to table of contents](#)
466 
467 ### xsd:decimal {#custom-2}
468 
469 The wsdl2h tool maps <i>`xsd:decimal`</i> to a string by default. To map <i>`xsd:decimal`</i> to
470 extended precision floating point:
471 
472  xsd__decimal = #import "custom/long_double.h" | long double
473 
474 By contrast to all other custom serializers, this serializer enables `long
475 double` natively without requiring a new binding name (`xsd__decimal` is NOT
476 defined).
477 
478 If your system supports <i>`quadmath.h`</i> quadruple precision floating point
479 `__float128`, you can map <i>`xsd:decimal`</i> to `xsd__decimal` that is an alias of
480 `__float128`:
481 
482  xsd__decimal = #import "custom/float128.h"
483 
484 @warning Beware that <i>`xsd:decimal`</i> is in principle a decimal value with arbitraty
485 lengths. A value range fault `SOAP_TYPE` will be thrown by the deserializer if
486 the value is out of range.
487 
488 In the XML payload the special values <i>`INF`</i>, <i>`-INF`</i>, <i>`NaN`</i>
489 represent plus or minus infinity and not-a-number, respectively.
490 
491 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/long_double.c`</i> with your
492 project.
493 
494 @see Section [numerical types](#toxsd5).
495 
496 🔝 [Back to table of contents](#)
497 
498 ### xsd:dateTime {#custom-3}
499 
500 The wsdl2h tool maps <i>`xsd:dateTime`</i> to `time_t` by default.
501 
502 The trouble with `time_t` when represented as 32 bit `long` integers is that it
503 is limited to dates between 1970 and 2038. A 64 bit `time_t` is safe to use if
504 the target platform supports it, but lack of 64 bit `time_t` portability may
505 still cause date range issues.
506 
507 For this reason `struct tm` should be used to represent wider date ranges. This
508 custom serializer avoids using date and time information in `time_t`. You get
509 the raw date and time information. You only lose the day of the week
510 information. It is always Sunday (`tm_wday=0`).
511 
512 To map <i>`xsd:dateTime`</i> to `xsd__dateTime` which is an alias of `struct tm`:
513 
514  xsd__dateTime = #import "custom/struct_tm.h"
515 
516 If the limited date range of `time_t` is not a problem but you want to increase
517 the time precision with fractional seconds, then we suggest to map <i>`xsd:dateTime`</i>
518 to `struct timeval`:
519 
520  xsd__dateTime = #import "custom/struct_timeval.h"
521 
522 If the limited date range of `time_t` is not a problem but you want to use the
523 C++11 time point type `std::chrono::system_clock::time_point` (which internally
524 uses `time_t`):
525 
526  xsd__dateTime = #import "custom/chrono_time_point.h"
527 
528 Again, we should make sure that the dates will not exceed the date range when
529 using the default `time_t` binding for <i>`xsd:dateTime`</i> or when binding
530 <i>`xsd:dateTime`</i> to `struct timeval` or to `std::chrono::system_clock::time_point`.
531 These are safe to use in applications that use <i>`xsd:dateTime`</i> to record date
532 stamps within a given window. Otherwise, we recommend the `struct tm` custom
533 serializer.
534 
535 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/struct_tm.c`</i> with your
536 project.
537 
538 You could even map <i>`xsd:dateTime`</i> to a plain string (use `char*` with C and
539 `std::string` with C++). For example:
540 
541  xsd__dateTime = | char*
542 
543 @see Section [date and time types](#toxsd7).
544 
545 🔝 [Back to table of contents](#)
546 
547 ### xsd:date {#custom-4}
548 
549 The wsdl2h tool maps <i>`xsd:date`</i> to a string by default. We can map <i>`xsd:date`</i> to
550 `struct tm`:
551 
552  xsd__date = #import "custom/struct_tm_date.h"
553 
554 The `xsd__date` type is an alias of `struct tm`. The serializer ignores the
555 time part and the deserializer only populates the date part of the struct,
556 setting the time to 00:00:00. There is no unreasonable limit on the date range
557 because the year field is stored as an integer (`int`).
558 
559 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/struct_tm_date.c`</i> with your
560 project.
561 
562 @see Section [date and time types](#toxsd7).
563 
564 🔝 [Back to table of contents](#)
565 
566 ### xsd:time {#custom-5}
567 
568 The wsdl2h tool maps <i>`xsd:time`</i> to a string by default. We can map <i>`xsd:time`</i> to
569 an `unsigned long long` (`ULONG64` or `uint64_t`) integer with microsecond time
570 precision:
571 
572  xsd__time = #import "custom/long_time.h"
573 
574 This type represents 00:00:00.000000 to 23:59:59.999999, from `0` to an upper
575 bound of `86399999999`. A microsecond resolution means that a 1 second
576 increment requires an increment of 1000000 in the integer value. The serializer
577 adds a UTC time zone.
578 
579 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/long_time.c`</i> with your
580 project.
581 
582 @see Section [date and time types](#toxsd7).
583 
584 🔝 [Back to table of contents](#)
585 
586 ### xsd:duration {#custom-6}
587 
588 The wsdl2h tool maps <i>`xsd:duration`</i> to a string by default, unless <i>`xsd:duration`</i>
589 is mapped to a `long long` (`LONG64` or `int64_t`) type with with millisecond
590 (ms) time duration precision:
591 
592  xsd__duration = #import "custom/duration.h"
593 
594 The `xsd__duration` type is a 64 bit signed integer that can represent
595 106,751,991,167 days forwards (positive) and backwards (negative) in time in
596 increments of 1 ms (1/1000 of a second).
597 
598 Rescaling of the duration value by may be needed when adding the duration value
599 to a `time_t` value, because `time_t` may or may not have a seconds resolution,
600 depending on the platform and possible changes to `time_t`.
601 
602 Rescaling is done automatically when you add a C++11 `std::chrono::nanoseconds`
603 value to a `std::chrono::system_clock::time_point` value. To use
604 `std::chrono::nanoseconds` as <i>`xsd:duration`</i>:
605 
606  xsd__duration = #import "custom/chrono_duration.h"
607 
608 This type can represent 384,307,168 days (2^63 nanoseconds) forwards and
609 backwards in time in increments of 1 ns (1/1,000,000,000 of a second).
610 
611 Certain observations with respect to receiving durations in years and months
612 apply to both of these serializer decoders for <i>`xsd:duration`</i>.
613 
614 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/duration.c`</i> with your
615 project.
616 
617 @see Section [time duration types](#toxsd8).
618 
619 🔝 [Back to table of contents](#)
620 
621 Custom Qt serializers for XSD types {#qt}
622 -----------------------------------
623 
624 The gSOAP distribution includes several custom serializers for Qt types. Also
625 Qt container classes are supported, see
626 [the built-in typemap.dat variables $CONTAINER, $POINTER and $SIZE](#typemap5).
627 
628 This feature requires gSOAP 2.8.34 or higher and Qt 4.8 or higher.
629 
630 Each Qt custom serializer has an interface header file for soapcpp2 and a C++
631 implementation file to be compiled with your project.
632 
633 Other Qt primitive types that are Qt `typedef`s of C/C++ types do not require a
634 custom serializer.
635 
636 🔝 [Back to table of contents](#)
637 
638 ### xsd:string {#qt-1}
639 
640 To use Qt strings instead of C++ strings, add the following definition to
641 <i>`typemap.dat`</i>:
642 
643  xsd__string = #import "custom/qstring.h"
644 
645 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/qstring.cpp`</i> with your
646 project.
647 
648 🔝 [Back to table of contents](#)
649 
650 ### xsd:base64Binary {#qt-2}
651 
652 To use Qt byte arrays for <i>`xsd:base64Binary`</i> instead of the
653 `xsd__base64Binary` class, add the following definition to <i>`typemap.dat`</i>:
654 
655  xsd__base64Binary = #import "custom/qbytearray_base64.h"
656 
657 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/qbytearray_base64.cpp`</i> with
658 your project.
659 
660 🔝 [Back to table of contents](#)
661 
662 ### xsd:hexBinary {#qt-3}
663 
664 To use Qt byte arrays for <i>`xsd:hexBinary`</i> instead of the `xsd__base64Binary`
665 class, add the following definition to <i>`typemap.dat`</i>:
666 
667  xsd__hexBinary = #import "custom/qbytearray_hex.h"
668 
669 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/qbytearray_hex.cpp`</i> with
670 your project.
671 
672 🔝 [Back to table of contents](#)
673 
674 ### xsd:dateTime {#qt-4}
675 
676 To use Qt QDateTime for <i>`xsd:dateTime`</i>, add the following definition to
677 <i>`typemap.dat`</i>:
678 
679  xsd__dateTime = #import "custom/datetime.h"
680 
681 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/qdatetime.cpp`</i> with
682 your project.
683 
684 🔝 [Back to table of contents](#)
685 
686 ### xsd:date {#qt-5}
687 
688 To use Qt QDate for <i>`xsd:date`</i>, add the following definition to
689 <i>`typemap.dat`</i>:
690 
691  xsd__date = #import "custom/qdate.h"
692 
693 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/qdate.cpp`</i> with your
694 project.
695 
696 🔝 [Back to table of contents](#)
697 
698 ### xsd:time {#qt-6}
699 
700 To use Qt QDate for <i>`xsd:time`</i>, add the following definition to
701 <i>`typemap.dat`</i>:
702 
703  xsd__time = #import "custom/qtime.h"
704 
705 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/qtime.cpp`</i> with your
706 project.
707 
708 🔝 [Back to table of contents](#)
709 
710 Class/struct member additions {#typemap3}
711 -----------------------------
712 
713 All generated classes and structs can be augmented with additional
714 members such as methods, constructors and destructors, and private members:
715 
716  prefix__type = $ member-declaration
717 
718 For example, we can add method declarations and private members to a class, say
719 `ns__record` as follows:
720 
721  ns__record = $ ns__record(const ns__record &); // copy constructor
722  ns__record = $ void print(); // a print method
723  ns__record = $ private: int status; // a private member
724 
725 Method declarations cannot include any code, because soapcpp2's input permits
726 only type declarations, not code.
727 
728 🔝 [Back to table of contents](#)
729 
730 Replacing XSD types by equivalent alternatives {#typemap4}
731 ----------------------------------------------
732 
733 Type replacements can be given to replace one type entirely with another given
734 type:
735 
736  prefix__type1 == prefix__type2
737 
738 This replaces all `prefix__type1` by `prefix__type2` in the wsdl2h output.
739 
740 @warning Do not agressively replace types, because this can cause XML schema
741 validation to fail when a value-type mismatch is encountered in the XML input.
742 Therefore, only replace similar types with other similar types that are wider
743 (e.g. `short` by `int` and `float` by `double`).
744 
745 🔝 [Back to table of contents](#)
746 
747 The built-in typemap.dat variables $CONTAINER, $POINTER and $SIZE {#typemap5}
748 -----------------------------------------------------------------
749 
750 The <i>`typemap.dat`</i> <b>`$CONTAINER`</b> variable defines the container type to use in
751 the wsdl2h-generated declarations for C++, which is `std::vector` by default.
752 For example, to use `std::list` as the container in the wsdl2h-generated
753 declarations we add the following line to <i>`typemap.dat`</i>:
754 
755  $CONTAINER = std::list
756 
757 Also a Qt container can be used instead of the default `std::vector`, for
758 example `QVector`:
759 
760  [
761  #include <QVector>
762  ]
763  $CONTAINER = QVector
764 
765 To remove containers, use <b>`wsdl2h -s`</b>. This also removes `std::string`,
766 but you can re-introduce `std::string` with
767 <b>`xsd__string = | std::string`</b> in <i>`typemap.dat`</i>.
768 
769 The <i>`typemap.dat`</i> <b>`$POINTER`</b> variable defines the smart pointer to use in the
770 wsdl2h-generated declarations for C++, which replaces the use of `*` pointers.
771 For example:
772 
773  $POINTER = std::shared_ptr
774 
775 Not all pointers in the generated output are replaced by smart pointers by
776 wsdl2h, such as pointers as union members and pointers as struct/class members
777 that point to arrays of values.
778 
779 @note The standard smart pointer `std::shared_ptr` is generally safe to use.
780 Other smart pointers such as `std::unique_ptr` and `std::auto_ptr` may cause
781 compile-time errors when classes have smart pointer members but no copy
782 constructor (a default copy constructor). A copy constructor is required for
783 non-shared smart pointer copying or swapping.
784 
785 Alternatives to `std::shared_ptr` of the form `NAMESPACE::shared_ptr` can be
786 assigned to <b>`$POINTER`</b> when the namespace `NAMESPACE` also implements
787 `NAMESPACE::make_shared` and when the shared pointer class provides `reset()`
788 and`get()` methods and the dereference operator. For example Boost
789 `boost::shared_ptr`:
790 
791  [
792  #include <boost/shared_ptr.hpp>
793  ]
794  $POINTER = boost::shared_ptr
795 
796 The user-defined content between <b>`[`</b> and <b>`]`</b> ensures that we include the Boost
797 header files that are needed to support `boost::shared_ptr` and
798 `boost::make_shared`.
799 
800 The variable <b>`$SIZE`</b> defines the type of array sizes, which is `int` by
801 default. For example, to change array size types to `size_t`:
802 
803  $SIZE = size_t
804 
805 Permissible types are `int` and `size_t`. This variable does not affect the
806 size of dynamic arrays, `xsd__hexBinary` and `xsd__base64Binary` types, which
807 is always `int`.
808 
809 🔝 [Back to table of contents](#)
810 
811 User-defined content {#typemap6}
812 --------------------
813 
814 Any other content to be generated by wsdl2h can be included in <i>`typemap.dat`</i> by
815 enclosing it within brackets <b>`[`</b> and <b>`]`</b> anywhere in the <i>`typemap.dat`</i> file.
816 Each of the two brackets must appear at the start of a new line.
817 
818 For example, we can add an `#import "wsa5.h"` to the wsdl2h-generated output as
819 follows:
820 
821  [
822  #import "import/wsa5.h"
823  ]
824 
825 which emits the `#import "import/wsa5.h"` literally at the start of the
826 wsdl2h-generated header file.
827 
828 🔝 [Back to table of contents](#)
829 
830 Mapping C/C++ to XML schema {#toxsd}
831 ===========================
832 
833 The soapcpp2 command generates the data binding implementation code from a data
834 binding interface <i>`file.h`</i>:
835 
836  soapcpp2 [options] file.h
837 
838 where <i>`file.h`</i> is a interface header file that declares the XML data
839 binding interface. The <i>`file.h`</i> is typically generated by wsdl2h, but
840 you can also declare one yourself. If so, add `//gsoap`
841 [directives](#directives) and declare in this file all our C/C++ types you want
842 to serialize in XML.
843 
844 You can also declare functions that will be converted to Web service operations
845 by soapcpp2. Global function declarations define service operations, which are
846 of the form:
847 
848 ~~~{.cpp}
849  int prefix__func(arg1, arg2, ..., argn, result);
850 ~~~
851 
852 where `arg1`, `arg2`, ..., `argn` are formal argument declarations of the input
853 and `result` is a formal argument for the output, which must be a pointer or
854 reference to the result object to be populated. More information on declaring
855 and implementing service operation functions can be found in the
856 [gSOAP user guide.](../../guide/html/index.html)
857 
858 🔝 [Back to table of contents](#)
859 
860 Overview of serializable C/C++ types {#toxsd1}
861 ------------------------------------
862 
863 The following C/C++ types are supported by soapcpp2 and mapped to XSD types
864 and constructs. See the subsections below for more details or follow the links.
865 
866 🔝 [Back to table of contents](#)
867 
868 ### List of Boolean types
869 
870 Boolean Type | Notes
871 ----------------------------- | -----
872 `bool` | C++ bool
873 `enum xsd__boolean` | C alternative to C++ `bool` with `false_` and `true_`
874 
875 @see Section [C++ bool and C alternative](#toxsd3).
876 
877 🔝 [Back to table of contents](#)
878 
879 ### List of enumeration and bitmask types
880 
881 Enumeration Type | Notes
882 ----------------------------- | -----
883 `enum` | enumeration
884 `enum class` | C++11 scoped enumeration, requires `soapcpp2 -c++11`
885 `enum*` | a bitmask that enumerates values 1, 2, 4, 8, ...
886 `enum* class` | C++11 scoped enumeration bitmask, requires `soapcpp2 -c++11`
887 
888 @see Section [enumerations and bitmasks](#toxsd4).
889 
890 🔝 [Back to table of contents](#)
891 
892 ### List of numerical types
893 
894 Numerical Type | Notes
895 ----------------------------- | -----
896 `char` | byte
897 `short` | 16 bit integer
898 `int` | 32 bit integer
899 `long` | 32 bit integer
900 `LONG64` | 64 bit integer
901 `xsd__integer` | 128 bit integer, use `#import "custom/int128.h"`
902 `long long` | same as `LONG64`
903 `unsigned char` | unsigned byte
904 `unsigned short` | unsigned 16 bit integer
905 `unsigned int` | unsigned 32 bit integer
906 `unsigned long` | unsigned 32 bit integer
907 `ULONG64` | unsigned 64 bit integer
908 `unsigned long long` | same as `ULONG64`
909 `int8_t` | same as `char`
910 `int16_t` | same as `short`
911 `int32_t` | same as `int`
912 `int64_t` | same as `LONG64`
913 `uint8_t` | same as `unsigned char`
914 `uint16_t` | same as `unsigned short`
915 `uint32_t` | same as `unsigned int`
916 `uint64_t` | same as `ULONG64`
917 `size_t` | transient type (not serializable)
918 `float` | 32 bit float
919 `double` | 64 bit float
920 `long double` | extended precision float, use `#import "custom/long_double.h"`
921 `xsd__decimal` | `quadmath.h` library 128 bit quadruple precision float, use `#import "custom/float128.h"`
922 `typedef` | declares a type name, with optional value range and string length bounds
923 
924 @see Section [numerical types](#toxsd5).
925 
926 🔝 [Back to table of contents](#)
927 
928 ### List of string types
929 
930 String Type | Notes
931 ----------------------------- | -----
932 `char*` | string (may contain UTF-8 with flag `SOAP_C_UTFSTRING`)
933 `wchar_t*` | wide string
934 `std::string` | C++ string (may contain UTF-8 with flag `SOAP_C_UTFSTRING`)
935 `std::wstring` | C++ wide string
936 `char[N]` | fixed-size string, requires `soapcpp2 -b`
937 `_QName` | normalized QName content
938 `_XML` | literal XML string content with wide characters in UTF-8
939 `typedef` | declares a new string type name, may restrict string length
940 
941 @see Section [string types](#toxsd6).
942 
943 🔝 [Back to table of contents](#)
944 
945 ### List of date and time types
946 
947 Date and Time Type | Notes
948 --------------------------------------- | -----
949 `time_t` | date and time point since epoch
950 `struct tm` | date and time point, use `#import "custom/struct_tm.h"`
951 `struct tm` | date point, use `#import "custom/struct_tm_date.h"`
952 `struct timeval` | date and time point, use `#import "custom/struct_timeval.h"`
953 `unsigned long long` | time point in microseconds, use `#import "custom/long_time.h"`
954 `std::chrono::system_clock::time_point` | date and time point, use `#import "custom/chrono_time_point.h"`
955 
956 @see Section [date and time types](#toxsd7).
957 
958 🔝 [Back to table of contents](#)
959 
960 ### List of time duration types
961 
962 Time Duration Type | Notes
963 ----------------------------- | -----
964 `long long` | duration in milliseconds, use `#import "custom/duration.h"`
965 `std::chrono::nanoseconds` | duration in nanoseconds, use `#import "custom/chrono_duration.h"`
966 
967 @see Section [time duration types](#toxsd8).
968 
969 🔝 [Back to table of contents](#)
970 
971 ### List of classes, structs, unions, pointers, containers, and arrays
972 
973 Classes, Structs, and Members | Notes
974 ----------------------------- | -----
975 `class` | C++ class with single inheritance only
976 `struct` | C struct or C++ struct without inheritance
977 `std::shared_ptr<T>` | C++11 smart shared pointer
978 `std::unique_ptr<T>` | C++11 smart pointer
979 `std::auto_ptr<T>` | C++ smart pointer
980 `std::deque<T>` | use `#import "import/stldeque.h"`
981 `std::list<T>` | use `#import "import/stllist.h"`
982 `std::vector<T>` | use `#import "import/stlvector.h"`
983 `std::set<T>` | use `#import "import/stlset.h"`
984 `template<T> class` | a container with `begin()`, `end()`, `size()`, `clear()`, and `insert()` methods
985 `T*` | pointer to data of type `T`
986 `T*` | as a class or struct member: points to data of type `T` or array of `T` with member `__size`
987 `T[N]` | as a class or struct member: fixed-size array of type `T`
988 `union` | as a class or struct member: requires a variant selector member `__union`
989 `void*` | as a class or struct member: requires a `__type` member to indicate the type of object pointed to
990 
991 @see Section [classes and structs](#toxsd9).
992 
993 🔝 [Back to table of contents](#)
994 
995 ### List of special classes and structs
996 
997 Special Classes and Structs | Notes
998 ----------------------------- | -----
999 Special Array class/struct | single and multidimensional SOAP Arrays
1000 Special Wrapper class/struct | complexTypes with simpleContent, wraps `__item` member
1001 `xsd__hexBinary` | binary content
1002 `xsd__base64Binary` | binary content and optional DIME/MIME/MTOM attachments
1003 `xsd__anyType` | DOM elements, use `#import "dom.h"`
1004 `@xsd__anyAttribute` | DOM attributes, use `#import "dom.h"`
1005 
1006 @see Section [special classes and structs](#toxsd10).
1007 
1008 🔝 [Back to table of contents](#)
1009 
1010 Colon notation versus name prefixing with XML tag name translation {#toxsd2}
1011 ------------------------------------------------------------------
1012 
1013 To bind C/C++ type names to XSD types, a simple form of name prefixing is used
1014 by the gSOAP tools by prepending the XML namespace prefix to the C/C++ type
1015 name with a pair of undescrores. This also ensures that name clashes cannot
1016 occur when multiple WSDL and XSD files are converted to C/C++. Also, C++
1017 namespaces are not sufficiently rich to capture XML schema namespaces
1018 accurately, for example when class members are associated with schema elements
1019 defined in another XML namespace and thus the XML namespace scope of the
1020 member's name is relevant, not just its type.
1021 
1022 However, from a C/C++ centric point of view this can be cumbersome. Therefore,
1023 colon notation is an alternative to physically augmenting C/C++ names with
1024 prefixes.
1025 
1026 For example, the following class uses colon notation to bind the `record` class
1027 to the <i>`urn:types`</i> schema:
1028 
1029 ~~~{.cpp}
1030  //gsoap ns schema namespace: urn:types
1031  class ns:record // binding 'ns:' to a type name
1032  {
1033  public:
1034  std::string name;
1035  uint64_t SSN;
1036  ns:record *spouse; // using 'ns:' with the type name
1037  ns:record(); // using 'ns:' here too
1038  ~ns:record(); // and here
1039  };
1040 ~~~
1041 
1042 The colon notation is stripped away by soapcpp2 when generating the data
1043 binding implementation code for our project. So the final code just uses
1044 `record` to identify this class and its constructor/destructor.
1045 
1046 When using colon notation make sure to be consistent and not use colon notation
1047 mixed with prefixed forms. The qualified name `ns:record` differs from `ns__record`,
1048 because `ns:record` is compiled to an unqualified `record` name in the source
1049 code output by the soapcpp2 tool.
1050 
1051 Colon notation also facilitates overruling the elementFormDefault and
1052 attributeFormDefault declaration that is applied to local elements and
1053 attributes, when declared as members of classes, structs, and unions. For more
1054 details, see [qualified and unqualified members](#toxsd9-6).
1055 
1056 A C/C++ identifier name (a type name, member name, function name, or parameter
1057 name) is translated to an XML tag name by the following rules:
1058 
1059 - Two leading underscores indicates that the identifier name has no XML tag
1060  name, i.e. this name is not visible in XML and is not translated.
1061 
1062 - A leading underscore is removed, but the underscore indicates that: **a**) a
1063  struct/class member name or parameter name has a wildcard XML tag name (i.e.
1064  matches any XML tag), or **b**) a type name that has a
1065  [document root element definition](#toxsd9-7).
1066 
1067 - Trailing underscores are removed (i.e. trailing underscores can be used to
1068  avoid name clashes with keywords).
1069 
1070 - Underscores within names are translated to hyphens (hyphens are more common
1071  in XML tag names).
1072 
1073 - `_USCORE` is translated to an underscore in the translated XML tag name.
1074 
1075 - `_DOT` is translated to a dot (<i>`.`</i>) in the translated XML tag name.
1076 
1077 - `_xHHHH` is translated to the Unicode character with code point HHHH (hex).
1078 
1079 - C++11 Unicode identifier name characters in UTF-8 are translated as-is.
1080 
1081 For example, the C/C++ namespace qualified identifier name `s_a__my_way` is
1082 translated to the XML tag name <i>`s-a:my-way`</i> by translating the prefix `s_a`
1083 and the local name `my_way`.
1084 
1085 Struct/class member and parameter name translation can be overruled by using
1086 [backtick XML tags](#toxsd9-5-1) (with gSOAP 2.8.30 and greater).
1087 
1088 🔝 [Back to table of contents](#)
1089 
1090 C++ bool and C alternative {#toxsd3}
1091 --------------------------
1092 
1093 The C++ `bool` type is bound to built-in XSD type <i>`xsd:boolean`</i>.
1094 
1095 The C alternative is to define an enumeration:
1096 
1097 ~~~{.cpp}
1098  enum xsd__boolean { false_, true_ };
1099 ~~~
1100 
1101 or by defining an enumeration in C with pseudo-scoped enumeration constants:
1102 
1103 ~~~{.cpp}
1104  enum xsd__boolean { xsd__boolean__false, xsd__boolean__true };
1105 ~~~
1106 
1107 The XML value space of these types is <i>`false`</i> and <i>`true`</i>, but also accepted
1108 are <i>`0`</i> and <i>`1`</i> values for <i>`false`</i> and <i>`true`</i>, respectively.
1109 
1110 To prevent name clashes, `false_` and `true_` have a trailing underscore in
1111 their `enum` symbols. Trailing underscores are removed from the XML value space.
1112 
1113 🔝 [Back to table of contents](#)
1114 
1115 Enumerations and bitmasks {#toxsd4}
1116 -------------------------
1117 
1118 Enumerations are mapped to XSD simpleType enumeration restrictions of
1119 <i>`xsd:string`</i>, <i>`xsd:QName`</i>, and <i>`xsd:long`</i>.
1120 
1121 Consider for example:
1122 
1123 ~~~{.cpp}
1124  enum ns__Color { RED, WHITE, BLUE };
1125 ~~~
1126 
1127 which maps to a simpleType restriction of <i>`xsd:string`</i> in the soapcpp2-generated
1128 schema:
1129 
1130 <div class="alt">
1131 ~~~{.xml}
1132  <simpleType name="Color">
1133  <restriction base="xsd:string">
1134  <enumeration value="RED"/>
1135  <enumeration value="WHITE"/>
1136  <enumeration value="BLUE"/>
1137  </restriction>
1138  </simpleType>
1139 ~~~
1140 </div>
1141 
1142 Enumeration name constants can be pseudo-scoped to prevent name clashes,
1143 because enumeration name constants have a global scope in C and C++:
1144 
1145 ~~~{.cpp}
1146  enum ns__Color { ns__Color__RED, ns__Color__WHITE, ns__Color__BLUE };
1147 ~~~
1148 
1149 You can also use C++11 scoped enumerations to prevent name clashes:
1150 
1151 ~~~{.cpp}
1152  enum class ns__Color : int { RED, WHITE, BLUE };
1153 ~~~
1154 
1155 Here, the enumeration class base type `: int` is optional. In place of `int`
1156 in the example above, we can also use `int8_t`, `int16_t`, `int32_t`, or
1157 `int64_t`.
1158 
1159 The XML value space of the enumertions defined above is <i>`RED`</i>, <i>`WHITE`</i>, and
1160 <i>`BLUE`</i>.
1161 
1162 Prefix-qualified enumeration name constants are mapped to simpleType
1163 restrictions of <i>`xsd:QName`</i>, for example:
1164 
1165 ~~~{.cpp}
1166  enum ns__types { xsd__int, xsd__float };
1167 ~~~
1168 
1169 which maps to a simpleType restriction of <i>`xsd:QName`</i> in the soapcpp2-generated
1170 schema:
1171 
1172 <div class="alt">
1173 ~~~{.xml}
1174  <simpleType name="types">
1175  <restriction base="xsd:QName">
1176  <enumeration value="xsd:int"/>
1177  <enumeration value="xsd:float"/>
1178  </restriction>
1179  </simpleType>
1180 ~~~
1181 </div>
1182 
1183 Enumeration name constants can be pseudo-numeric as follows:
1184 
1185 ~~~{.cpp}
1186  enum ns__Primes { _3 = 3, _5 = 5, _7 = 7, _11 = 11 };
1187 ~~~
1188 
1189 which maps to a simpleType restriction of <i>`xsd:long`</i>:
1190 
1191 <div class="alt">
1192 ~~~{.xml}
1193  <simpleType name="Color">
1194  <restriction base="xsd:long">
1195  <enumeration value="3"/>
1196  <enumeration value="5"/>
1197  <enumeration value="7"/>
1198  <enumeration value="11"/>
1199  </restriction>
1200  </simpleType>
1201 ~~~
1202 </div>
1203 
1204 The XML value space of this type is <i>`3`</i>, <i>`5`</i>, <i>`7`</i>, and <i>`11`</i>.
1205 
1206 Besides (pseudo-) scoped enumerations, another way to prevent name clashes
1207 accross enumerations is to start an enumeration name constant with one
1208 underscore or followed it by any number of underscores, which makes it
1209 unique. The leading and trailing underscores are removed from the XML value
1210 space.
1211 
1212 ~~~{.cpp}
1213  enum ns__ABC { A, B, C };
1214  enum ns__BA { B, A }; // BAD: B = 1 but B is already defined as 2
1215  enum ns__BA_ { B_, A_ }; // OK
1216 ~~~
1217 
1218 The gSOAP soapcpp2 tool permits reusing enumeration name constants across
1219 (non-scoped) enumerations as long as these values are assigned the same
1220 constant. Therefore, the following is permitted:
1221 
1222 ~~~{.cpp}
1223  enum ns__Primes { _3 = 3, _5 = 5, _7 = 7, _11 = 11 };
1224  enum ns__Throws { _1 = 1, _2 = 2, _3 = 3, _4 = 4, _5 = 5, _6 = 6 };
1225 ~~~
1226 
1227 A bitmask type is an `enum*` "product enumeration" with a geometric,
1228 power-of-two sequence of values assigned to the enumeration constants:
1229 
1230 ~~~{.cpp}
1231  enum* ns__Options { SSL3, TLS10, TLS11, TLS12, TLS13 };
1232 ~~~
1233 
1234 where the product enum assigns 1 to `SSL3`, 2 to `TLS10`, 4 to `TLS11`, 8
1235 to `TLS12`, and 16 to `TLS13`, which allows these enumeration constants to be
1236 used in composing bitmasks with `|` (bitwise or) `&` (bitwise and), and `~`
1237 (bitwise not):
1238 
1239 ~~~{.cpp}
1240  enum ns__Options options = (enum ns__Options)(SSL3 | TLS10 | TLS11 | TLS12 | TLS13);
1241  if (options & SSL3) // if SSL3 is an option, warn and remove from options
1242  {
1243  warning();
1244  options &= ~SSL3;
1245  }
1246 ~~~
1247 
1248 The bitmask type maps to a simpleType list restriction of <i>`xsd:string`</i> in the
1249 soapcpp2-generated XML schema:
1250 
1251 <div class="alt">
1252 ~~~{.xml}
1253  <simpleType name="Options">
1254  <list>
1255  <restriction base="xsd:string">
1256  <enumeration value="SSL3"/>
1257  <enumeration value="TLS10"/>
1258  <enumeration value="TLS11"/>
1259  <enumeration value="TLS12"/>
1260  <enumeration value="TLS13"/>
1261  </restriction>
1262  </list>
1263  </simpleType>
1264 ~~~
1265 </div>
1266 
1267 The XML value space of this type consists of all 16 possible subsets of the
1268 four values, represented by an XML string with space-separated values. For
1269 example, the bitmask `TLS10 | TLS11 | TLS12` equals 14 and is represented by
1270 the XML text <i>`TLS10 TLS11 TLS12`</i>.
1271 
1272 You can also use C++11 scoped enumerations with bitmasks using `enum*` product
1273 enumerations:
1274 
1275 ~~~{.cpp}
1276  enum* class ns__Options { SSL3, TLS10, TLS11, TLS12, TLS13 };
1277 ~~~
1278 
1279 The base type of a scoped enumeration bitmask, when explicitly given, is
1280 ignored. The base type is either `int` or `int64_t`, depending on the number
1281 of constants enumerated in the bitmask.
1282 
1283 To convert `enum` name constants and bitmasks to a string, we use the
1284 auto-generated function for enum `T`:
1285 
1286 ~~~{.cpp}
1287  const char *soap_T2s(struct soap*, enum T val)
1288 ~~~
1289 
1290 The string returned is stored in an internal buffer of the current `soap`
1291 context, so you should copy it to keep it from being overwritten. For example,
1292 use `char *soap_strdup(struct soap*, const char*)`.
1293 
1294 To convert a string to an `enum` constant or bitmask, we use the auto-generated
1295 function
1296 
1297 ~~~{.cpp}
1298  int soap_s2T(struct soap*, const char *str, enum T *val)
1299 ~~~
1300 
1301 This function takes the name (or names, space-separated for bitmasks) of
1302 the enumeration constant in a string `str`. Names should be given without the
1303 pseudo-scope prefix and without trailing underscores. The function sets `val`
1304 to the corresponding integer enum constant or to a bitmask. The function
1305 returns `SOAP_OK` (zero) on success or an error if the string is not a valid
1306 enumeration name.
1307 
1308 🔝 [Back to table of contents](#)
1309 
1310 Numerical types {#toxsd5}
1311 ---------------
1312 
1313 Integer and floating point types are mapped to the equivalent built-in XSD
1314 types with the same sign and bit width.
1315 
1316 The `size_t` type is transient (not serializable) because its width is platform
1317 dependent. We recommend to use `uint64_t` instead.
1318 
1319 The XML value space of integer types are their decimal representations without
1320 loss of precision.
1321 
1322 The XML value space of floating point types are their decimal representations.
1323 The decimal representations are formatted with the printf format string `"%.9G"`
1324 for floats and the printf format string `"%.17lG"` for double. To change the
1325 format strings, we can assign new strings to the following `soap` context
1326 members:
1327 
1328 ~~~{.cpp}
1329  soap.float_format = "%g";
1330  soap.double_format = "%lg";
1331  soap.long_double_format = "%Lg";
1332 ~~~
1333 
1334 Decimal representations may result in a loss of precision of the least
1335 significant decimal. Therefore, the format strings that are used by default
1336 are sufficiently precise to avoid loss, but this may result in long decimal
1337 fractions in the XML value space.
1338 
1339 The `long double` extended floating point type requires a custom serializer:
1340 
1341 ~~~{.cpp}
1342  #import "custom/long_double.h"
1343  ... // use long double
1344 ~~~
1345 
1346 You can now use `long double`, which has a serializer that serializes this type
1347 as <i>`xsd:decimal`</i>. Compile and link your code with the file
1348 <i>`gsoap/custom/long_double.c`</i>.
1349 
1350 The value space of floating point values includes the special values
1351 <i>`INF`</i>, <i>`-INF`</i>, and <i>`NaN`</i>. You can check a value for plus
1352 or minus infinity and not-a-number as follows:
1353 
1354 ~~~{.cpp}
1355  soap_isinf(x) && x > 0 // is x INF?
1356  soap_isinf(x) && x < 0 // is x -INF?
1357  soap_isnan(x) // is x NaN?
1358 ~~~
1359 
1360 To assign these values, use:
1361 
1362 ~~~{.cpp}
1363  // x is float // x is double, long double, or __float128
1364  x = FLT_PINFY; x = DBL_PINFTY;
1365  x = FLT_NINFY; x = DBL_NINFTY;
1366  x = FLT_NAN; x = DBL_NAN;
1367 ~~~
1368 
1369 If your system supports `__float128` then you can also use this 128 bit
1370 floating point type with a custom serializer:
1371 
1372 ~~~{.cpp}
1373  #import "custom/float128.h"
1374  ... // use xsd__decimal
1375 ~~~
1376 
1377 Then use the `xsd__decimal` alias of `__float128`, which has a serializer. Do
1378 not use `__float128` directly, which is transient (not serializable).
1379 
1380 To check for <i>`INF`</i>, <i>`-INF`</i>, and <i>`NaN`</i> of a `__float128`
1381 value use:
1382 
1383 ~~~{.cpp}
1384  isinfq(x) && x > 0 // is x INF?
1385  isinfq(x) && x < 0 // is x -INF?
1386  isnanq(x) // is x NaN?
1387 ~~~
1388 
1389 The range of a `typedef`-defined numerical type can be restricted using the range
1390 `:` operator with inclusive lower and upper bounds. For example:
1391 
1392 ~~~{.cpp}
1393  typedef int ns__narrow -10 : 10;
1394 ~~~
1395 
1396 This maps to a simpleType restriction of <i>`xsd:int`</i> in the soapcpp2-generated
1397 schema:
1398 
1399 <div class="alt">
1400 ~~~{.xml}
1401  <simpleType name="narrow">
1402  <restriction base="xsd:int">
1403  <minInclusive value="-10"/>
1404  <maxInclusive value="10"/>
1405  </restriction>
1406  </simpleType>
1407 ~~~
1408 </div>
1409 
1410 The lower and upper bound of a range are optional. When omitted, values are
1411 not bound from below or from above, respectively.
1412 
1413 The range of a floating point `typedef`-defined type can be restricted within
1414 floating point constant bounds.
1415 
1416 Also with a floating point `typedef` a `printf`-format pattern can be given of the
1417 form `"%[width][.precision]f"` to format decimal values using the given width
1418 and precision fields:
1419 
1420 ~~~{.cpp}
1421  typedef float ns__PH "%5.2f" 0.0 : 14.0;
1422 ~~~
1423 
1424 This maps to a simpleType restriction of <i>`xsd:float`</i> in the soapcpp2-generated
1425 schema:
1426 
1427 <div class="alt">
1428 ~~~{.xml}
1429  <simpleType name="PH">
1430  <restriction base="xsd:float">
1431  <totalDigits value="5"/>
1432  <fractionDigits value="2"/>
1433  <minInclusive value="0"/>
1434  <maxInclusive value="14"/>
1435  </restriction>
1436  </simpleType>
1437 ~~~
1438 </div>
1439 
1440 For exclusive bounds, we use the `<` operator instead of the `:` range
1441 operator:
1442 
1443 ~~~{.cpp}
1444  typedef float ns__epsilon 0.0 < 1.0;
1445 ~~~
1446 
1447 Values `eps` of `ns__epsilon` are restricted between `0.0 < eps < 1.0`.
1448 
1449 This maps to a simpleType restriction of <i>`xsd:float`</i> in the soapcpp2-generated
1450 schema:
1451 
1452 <div class="alt">
1453 ~~~{.xml}
1454  <simpleType name="epsilon">
1455  <restriction base="xsd:float">
1456  <minExclusive value="0"/>
1457  <maxExclusive value="1"/>
1458  </restriction>
1459  </simpleType>
1460 ~~~
1461 </div>
1462 
1463 To make just one of the bounds exclusive, while keeping the other bound
1464 inclusive, we add a `<` on the left or on the right side of the range ':'
1465 operator. For example:
1466 
1467 ~~~{.cpp}
1468  typedef float ns__pos 0.0 < : ; // 0.0 < pos
1469  typedef float ns__neg : < 0.0 ; // neg < 0.0
1470 ~~~
1471 
1472 It is valid to make both left and right side exclusive with `< : <` which is in
1473 fact identical to the exlusive range `<` operator:
1474 
1475 ~~~{.cpp}
1476  typedef float ns__epsilon 0.0 < : < 1.0; // 0.0 < eps < 1.0
1477 ~~~
1478 
1479 It helps to think of the `:` as a placeholder of the value between the two
1480 bounds, which is easier to memorize than the shorthand forms of bounds from
1481 which the `:` is removed:
1482 
1483 | bounds | validation check | shorthand |
1484 | ------------ | ---------------- | ----------- |
1485 | `1 : ` | 1 <= x | `1 ` |
1486 | `1 : 10 ` | 1 <= x <= 10 | |
1487 | ` : 10 ` | x <= 10 | |
1488 | `1 < : < 10` | 1 < x < 10 | `1 < 10 ` |
1489 | `1 : < 10` | 1 <= x < 10 | |
1490 | ` : < 10` | x < 10 | ` < 10 ` |
1491 | `1 < : ` | 1 < x | `1 < ` |
1492 | `1 < : 10 ` | 1 < x <= 10 | |
1493 
1494 Besides `float`, also `double` and `long double` values can be restricted. For
1495 example, consider a nonzero probability extended floating point precision type:
1496 
1497 ~~~{.cpp}
1498  #import "custom/long_double.h"
1499  typedef long double ns__probability "%16Lg" 0.0 < : 1.0;
1500 ~~~
1501 
1502 Value range restrictions are validated by the parser for all inbound XML data.
1503 A type fault `SOAP_TYPE` will be thrown by the deserializer if the value is out
1504 of range.
1505 
1506 Finally, if your system supports `__int128_t` then you can also use this 128
1507 bit integer type with a custom serializer:
1508 
1509 ~~~{.cpp}
1510  #import "custom/int128.h"
1511  ... // use xsd__integer
1512 ~~~
1513 
1514 Use the `xsd__integer` alias of `__int128_t`, which has a serializer. Do not
1515 use `__int128_t` directly, which is transient (not serializable).
1516 
1517 To convert numeric values to a string, we use the auto-generated function for
1518 numeric type `T`:
1519 
1520 ~~~{.cpp}
1521  const char *soap_T2s(struct soap*, T val)
1522 ~~~
1523 
1524 For numeric types `T`, the string returned is stored in an internal buffer of
1525 the current `soap` context, so you should copy it to keep it from being
1526 overwritten. For example, use `char *soap_strdup(struct soap*, const char*)`.
1527 
1528 To convert a string to a numeric value, we use the auto-generated function
1529 
1530 ~~~{.cpp}
1531  int soap_s2T(struct soap*, const char *str, T *val)
1532 ~~~
1533 
1534 where `T` is for example `int`, `LONG64`, `float`, `decimal` (the custom
1535 serializer name of `long double`) or `xsd__integer` (the custom serializer name
1536 of `__int128_t`). The function `soap_s2T` returns `SOAP_OK` on success or an
1537 error when the value is not numeric. For floating point types, `"INF"`, `"-INF"`
1538 and `"NaN"` are valid strings to convert to numbers.
1539 
1540 🔝 [Back to table of contents](#)
1541 
1542 String types {#toxsd6}
1543 ------------
1544 
1545 String types are mapped to the built-in <i>`xsd:string`</i> and <i>`xsd:QName`</i> XSD types.
1546 
1547 The wide strings `wchar_t*` and `std::wstring` may contain Unicode that is
1548 preserved in the XML value space.
1549 
1550 Strings `char*` and `std::string` can only contain extended Latin, but we can
1551 store UTF-8 content that is preserved in the XML value space when the `soap`
1552 context is initialized with the flag `SOAP_C_UTFSTRING`.
1553 
1554 @warning Beware that many XML 1.0 parsers reject all control characters (those
1555 between `#x1` and `#x1F`) except for `#x9`, `#xA`, and `#xD`. With the
1556 newer XML 1.1 version parsers (including gSOAP) you should be fine.
1557 
1558 The length of a string of a `typedef`-defined string type can be restricted:
1559 
1560 ~~~{.cpp}
1561  typedef std::string ns__password 6 : 16;
1562 ~~~
1563 
1564 which maps to a simpleType restriction of <i>`xsd:string`</i> in the soapcpp2-generated
1565 schema:
1566 
1567 <div class="alt">
1568 ~~~{.xml}
1569  <simpleType name="password">
1570  <restriction base="xsd:string">
1571  <minLength value="6"/>
1572  <maxLength value="16"/>
1573  </restriction>
1574  </simpleType>
1575 ~~~
1576 </div>
1577 
1578 String length restrictions are validated by the parser for inbound XML data.
1579 A value length fault `SOAP_LENGTH` will be thrown by the deserializer if the
1580 string is too long or too short.
1581 
1582 In addition, an XSD regex pattern restriction can be associated with a string
1583 typedef:
1584 
1585 ~~~{.cpp}
1586  typedef std::string ns__password "([a-zA-Z]|[0-9]|-)+" 6 : 16;
1587 ~~~
1588 
1589 which maps to a simpleType restriction of <i>`xsd:string`</i> in the soapcpp2-generated
1590 schema:
1591 
1592 <div class="alt">
1593 ~~~{.xml}
1594  <simpleType name="password">
1595  <restriction base="xsd:string">
1596  <pattern value="([a-zA-Z0-9]|-)+"/>
1597  <minLength value="6"/>
1598  <maxLength value="16"/>
1599  </restriction>
1600  </simpleType>
1601 ~~~
1602 </div>
1603 
1604 Pattern restrictions are validated by the parser for inbound XML data only if
1605 the `soap::fsvalidate` and `soap::fwvalidate` callbacks are defined.
1606 
1607 Exclusive length bounds can be used with strings:
1608 
1609 ~~~{.cpp}
1610  typedef std::string ns__string255 : < 256; // same as 0 : 255
1611 ~~~
1612 
1613 Fixed-size strings (`char[N]`) are rare occurrences in the wild, but apparently
1614 still used in some projects to store strings. To facilitate fixed-size string
1615 serialization, use <b>`soapcpp2 -b`</b> option <b>`-b`</b>. For example:
1616 
1617 ~~~{.cpp}
1618  typedef char ns__buffer[10]; // requires soapcpp2 option -b
1619 ~~~
1620 
1621 which maps to a simpleType restriction of <i>`xsd:string`</i> in the soapcpp2-generated
1622 schema:
1623 
1624 <div class="alt">
1625 ~~~{.xml}
1626  <simpleType name="buffer">
1627  <restriction base="xsd:string">
1628  <maxLength value="9"/>
1629  </restriction>
1630  </simpleType>
1631 ~~~
1632 </div>
1633 
1634 Fixed-size strings must contain NUL-terminated text and should not contain raw
1635 binary data. Also, the length limitation is more restrictive for UTF-8 content
1636 (enabled with the `SOAP_C_UTFSTRING`) that requires multibyte character
1637 encodings. As a consequence, UTF-8 content may be truncated to fit.
1638 
1639 Raw binary data can be stored in a `xsd__base64Binary` or `xsd__hexBinary`
1640 structure, or transmitted as a MIME attachment.
1641 
1642 The built-in `_QName` type is a regular C string type (`char*`) that maps to
1643 <i>`xsd:QName`</i> but has the added advantage that it holds normalized qualified names.
1644 There are actually two forms of normalized QName content, to ensure any QName
1645 is represented accurately:
1646 
1647 ~~~{.cpp}
1648  "prefix:name"
1649  "\"URI\":name"
1650 ~~~
1651 
1652 The first form of string is used when the prefix (and the binding URI) is
1653 defined in the namespace table and is bound to a URI (see the .nsmap file).
1654 The second form is used when the URI is not defined in the namespace table and
1655 therefore no prefix is available to bind and normalize the URI to.
1656 
1657 A `_QName` string may contain a sequence of space-separated QName values, not
1658 just one, and all QName values are normalized to the format shown above.
1659 
1660 To define a `std::string` base type for <i>`xsd:QName`</i>, we use a `typedef`:
1661 
1662 ~~~{.cpp}
1663  typedef std::string xsd__QName;
1664 ~~~
1665 
1666 The `xsd__QName` string content is normalized, just as with the `_QName`
1667 normalization.
1668 
1669 To serialize strings that contain literal XML content to be reproduced in the
1670 XML value space, use the built-in `_XML` string type, which is a regular C
1671 string type (`char*`) that maps to plain XML CDATA.
1672 
1673 To define a `std::string` base type for literal XML content, use a `typedef`:
1674 
1675 ~~~{.cpp}
1676  typedef std::string XML;
1677 ~~~
1678 
1679 Strings can hold any of the values of the XSD built-in primitive types. We can
1680 use a string `typedef` to declare the use of the string type as a XSD built-in
1681 type:
1682 
1683 ~~~{.cpp}
1684  typedef std::string xsd__token;
1685 ~~~
1686 
1687 You must ensure that the string values we populate in this type conform to the
1688 XML standard, which in case of <i>`xsd:token`</i> is the lexical and value spaces of
1689 <i>`xsd:token`</i> are the sets of all strings after whitespace replacement of any
1690 occurrence of `#x9`, `#xA` , and `#xD` by `#x20` and collapsing.
1691 
1692 As of version 2.8.49, the gSOAP parser will automatically collapse or replace
1693 the white space content when receiving data for XSD types that require white
1694 space collapsed or replaced. This normalization is applied to strings
1695 directly. The decision to collapse or replace is based on the `typedef` name
1696 corresponding to the built-in string-based XSD type.
1697 
1698 To copy `char*` or `wchar_t*` strings with a context that manages the allocated
1699 memory, use functions
1700 
1701 ~~~{.cpp}
1702  char *soap_strdup(struct soap*, const char*)
1703  wchar_t *soap_wstrdup(struct soap*, const wchar_t*)
1704 ~~~
1705 
1706 To convert a wide string to a UTF-8 encoded string, use function
1707 
1708 ~~~{.cpp}
1709  const char* SOAP_FMAC2 soap_wchar2s(struct soap*, const wchar_t *s)
1710 ~~~
1711 
1712 The function allocates and returns a string, with its memory being managed by
1713 the context.
1714 
1715 To convert a UTF-8 encoded string to a wide string, use function
1716 
1717 ~~~{.cpp}
1718  int soap_s2wchar(struct soap*, const char *from, wchar_t **to, long minlen, long maxlen)
1719 ~~~
1720 
1721 where `to` is set to point to an allocated `wchar_t*` string. Pass `-1` for
1722 `minlen` and `maxlen` to ignore length constraints on the target string. The
1723 function returns `SOAP_OK` or an error when the length constraints are not met.
1724 
1725 🔝 [Back to table of contents](#)
1726 
1727 Date and time types {#toxsd7}
1728 -------------------
1729 
1730 The C/C++ `time_t` type is mapped to the built-in <i>`xsd:dateTime`</i> XSD type that
1731 represents a date and time within a time zone (typically UTC).
1732 
1733 The XML value space contains ISO 8601 Gregorian time instances of the form
1734 <i>`[-]CCYY-MM-DDThh:mm:ss.sss[Z|(+|-)hh:mm]`</i>, where <i>`Z`</i> is the UTC time zone
1735 or a time zone offset <i>`(+|-)hh:mm]`</i> from UTC is used.
1736 
1737 A `time_t` value is considered and represented in UTC by the serializer.
1738 
1739 Because the `time_t` value range is restricted to dates after 01/01/1970 and
1740 before 2038 assuming `time_t` is a `long` 32 bit, care must be taken to ensure
1741 the range of <i>`xsd:dateTime`</i> values in XML exchanges do not exceed the `time_t`
1742 range.
1743 
1744 This restriction does not hold for `struct tm` (<i>`time.h`</i> library), which we can use
1745 to store and exchange a date and time in UTC without date range restrictions.
1746 The serializer uses the `struct tm` members directly for the XML value space of
1747 <i>`xsd:dateTime`</i>:
1748 
1749 ~~~{.cpp}
1750  struct tm
1751  {
1752  int tm_sec; // seconds (0 - 60)
1753  int tm_min; // minutes (0 - 59)
1754  int tm_hour; // hours (0 - 23)
1755  int tm_mday; // day of month (1 - 31)
1756  int tm_mon; // month of year (0 - 11)
1757  int tm_year; // year - 1900
1758  int tm_wday; // day of week (Sunday = 0) (NOT USED)
1759  int tm_yday; // day of year (0 - 365) (NOT USED)
1760  int tm_isdst; // is summer time in effect?
1761  char* tm_zone; // abbreviation of timezone (NOT USED)
1762  };
1763 ~~~
1764 
1765 You will lose the day of the week information. It is always Sunday
1766 (`tm_wday=0`) and the day of the year is not set either. The time zone is UTC.
1767 
1768 This `struct tm` type is mapped to the built-in <i>`xsd:dateTime`</i> XSD type and
1769 serialized with the custom serializer <i>`gsoap/custom/struct_tm.h`</i> that declares a
1770 `xsd__dateTime` type:
1771 
1772 ~~~{.cpp}
1773  #import "custom/struct_tm.h" // import typedef struct tm xsd__dateTime;
1774  ... // use xsd__dateTime
1775 ~~~
1776 
1777 Compile and link your code with <i>`gsoap/custom/struct_tm.c`</i>.
1778 
1779 The `struct timeval` (<i>`sys/time.h`</i> library) type is mapped to the
1780 built-in <i>`xsd:dateTime`</i> XSD type and serialized with the custom serializer
1781 <i>`gsoap/custom/struct_timeval.h`</i> that declares a `xsd__dateTime` type:
1782 
1783 ~~~{.cpp}
1784  #import "custom/struct_timeval.h" // import typedef struct timeval xsd__dateTime;
1785  ... // use xsd__dateTime
1786 ~~~
1787 
1788 Compile and link your code with <i>`gsoap/custom/struct_timeval.c`</i>.
1789 
1790 The same value range restrictions apply to `struct timeval` as they apply to
1791 `time_t`. The added benefit of `struct timeval` is the addition of a
1792 microsecond-precise clock:
1793 
1794 ~~~{.cpp}
1795  struct timeval
1796  {
1797  time_t tv_sec; // seconds since Jan. 1, 1970
1798  suseconds_t tv_usec; // and microseconds
1799  };
1800 ~~~
1801 
1802 A C++11 `std::chrono::system_clock::time_point` type is mapped to the built-in
1803 <i>`xsd:dateTime`</i> XSD type and serialized with the custom serializer
1804 <i>`gsoap/custom/chrono_time_point.h`</i> that declares a `xsd__dateTime` type:
1805 
1806 ~~~{.cpp}
1807  #import "custom/chrono_time_point.h" // import typedef std::chrono::system_clock::time_point xsd__dateTime;
1808  ... // use xsd__dateTime
1809 ~~~
1810 
1811 Compile and link your code with <i>`gsoap/custom/chrono_time_point.cpp`</i>.
1812 
1813 The `struct tm` type is mapped to the built-in <i>`xsd:date`</i> XSD type and serialized
1814 with the custom serializer <i>`gsoap/custom/struct_tm_date.h`</i> that declares a
1815 `xsd__date` type:
1816 
1817 ~~~{.cpp}
1818  #import "custom/struct_tm_date.h" // import typedef struct tm xsd__date;
1819  ... // use xsd__date
1820 ~~~
1821 
1822 Compile and link your code with <i>`gsoap/custom/struct_tm_date.c`</i>.
1823 
1824 The XML value space of <i>`xsd:date`</i> are Gregorian calendar dates of the form
1825 <i>`[-]CCYY-MM-DD[Z|(+|-)hh:mm]`</i> with a time zone.
1826 
1827 The serializer ignores the time part and the deserializer only populates the
1828 date part of the struct, setting the time to 00:00:00. There is no unreasonable
1829 limit on the date range because the year field is stored as an integer (`int`).
1830 
1831 An `unsigned long long` (`ULONG64` or `uint64_t`) type that contains a 24 hour
1832 time in microseconds UTC is mapped to the built-in <i>`xsd:time`</i> XSD type and
1833 serialized with the custom serializer <i>`gsoap/custom/long_time.h`</i> that declares a
1834 `xsd__time` type:
1835 
1836 ~~~{.cpp}
1837  #import "custom/long_time.h" // import typedef unsigned long long xsd__time;
1838  ... // use xsd__time
1839 ~~~
1840 
1841 Compile and link your code with <i>`gsoap/custom/long_time.c`</i>.
1842 
1843 This type represents `00:00:00.000000` to `23:59:59.999999`, from 0 to an
1844 upper bound of 86,399,999,999. A microsecond resolution means that a 1 second
1845 increment requires an increment of 1,000,000 in the integer value.
1846 
1847 The XML value space of <i>`xsd:time`</i> are points in time recurring each day of the
1848 form <i>`hh:mm:ss.sss[Z|(+|-)hh:mm]`</i>, where <i>`Z`</i> is the UTC time zone or a time
1849 zone offset from UTC is used. The `xsd__time` value is always considered and
1850 represented in UTC by the serializer.
1851 
1852 To convert date and/or time values to a string, we use the auto-generated
1853 function for type `T`:
1854 
1855 ~~~{.cpp}
1856  const char *soap_T2s(struct soap*, T val)
1857 ~~~
1858 
1859 For date and time types `T`, the string returned is stored in an internal
1860 buffer of the current `soap` context, so you should copy it to keep it from being
1861 overwritten. For example, use `char *soap_strdup(struct soap*, const char*)`.
1862 
1863 To convert a string to a date/time value, we use the auto-generated function
1864 
1865 ~~~{.cpp}
1866  int soap_s2T(struct soap*, const char *str, T *val)
1867 ~~~
1868 
1869 where `T` is for example `dateTime` (for `time_t`), `xsd__dateTime` (for
1870 `struct tm`, `struct timeval`, or `std::chrono::system_clock::time_point`).
1871 The function `soap_s2T` returns `SOAP_OK` on success or an error when the value
1872 is not a date/time.
1873 
1874 🔝 [Back to table of contents](#)
1875 
1876 Time duration types {#toxsd8}
1877 -------------------
1878 
1879 The XML value space of <i>`xsd:duration`</i> are values of the form <i>`PnYnMnDTnHnMnS`</i>
1880 where the capital letters are delimiters. Delimiters may be omitted when the
1881 corresponding member is not used.
1882 
1883 A `long long` (`LONG64` or `int64_t`) type that contains a duration (time
1884 lapse) in milliseconds is mapped to the built-in <i>`xsd:duration`</i> XSD type and
1885 serialized with the custom serializer <i>`gsoap/custom/duration.h`</i> that declares a
1886 `xsd__duration` type:
1887 
1888 ~~~{.cpp}
1889  #import "custom/duration.h" // import typedef long long xsd__duration;
1890  ... // use xsd__duration
1891 ~~~
1892 
1893 Compile and link your code with <i>`gsoap/custom/duration.c`</i>.
1894 
1895 The duration type `xsd__duration` can represent 106,751,991,167 days forward
1896 and backward with millisecond precision.
1897 
1898 Durations that exceed a month are always output in days, rather than months to
1899 avoid days-per-month conversion inacurracies.
1900 
1901 Durations that are received in years and months instead of total number of days
1902 from a reference point are not well defined, since there is no accepted
1903 reference time point (it may or may not be the current time). The decoder
1904 simple assumes that there are 30 days per month. For example, conversion of
1905 "P4M" gives 120 days. Therefore, the durations "P4M" and "P120D" are assumed
1906 to be identical, which is not necessarily true depending on the reference point
1907 in time.
1908 
1909 Rescaling of the duration value by may be needed when adding the duration value
1910 to a `time_t` value, because `time_t` may or may not have a seconds resolution,
1911 depending on the platform and possible changes to `time_t`.
1912 
1913 Rescaling is done automatically when you add a C++11 `std::chrono::nanoseconds`
1914 value to a `std::chrono::system_clock::time_point` value. To use
1915 `std::chrono::nanoseconds` as <i>`xsd:duration`</i>:
1916 
1917 ~~~{.cpp}
1918  #import "custom/chrono_duration.h" // import typedef std::chrono::duration xsd__duration;
1919  ... // use xsd__duration
1920 ~~~
1921 
1922 Compile and link your code with <i>`gsoap/custom/chrono_duration.cpp`</i>.
1923 
1924 This type can represent 384,307,168 days (2^63 nanoseconds) forwards and
1925 backwards in time in increments of 1 ns (1/1000000000 second).
1926 
1927 The same observations with respect to receiving durations in years and months
1928 apply to this serializer's decoder.
1929 
1930 To convert duration values to a string, we use the auto-generated function
1931 
1932 ~~~{.cpp}
1933  const char *soap_xsd__duration2s(struct soap*, xsd__duration val)
1934 ~~~
1935 
1936 The string returned is stored in an internal buffer, so you should copy it to
1937 keep it from being overwritten, Use `soap_strdup(struct soap*, const char*)`
1938 for example to copy this string.
1939 
1940 To convert a string to a duration value, we use the auto-generated function
1941 
1942 ~~~{.cpp}
1943  int soap_s2xsd__dateTime(struct soap*, const char *str, xsd__dateTime *val)
1944 ~~~
1945 
1946 The function returns `SOAP_OK` on success or an error when the value is not a
1947 duration.
1948 
1949 🔝 [Back to table of contents](#)
1950 
1951 Classes and structs {#toxsd9}
1952 -------------------
1953 
1954 Classes and structs are mapped to XSD complexTypes. The XML value space
1955 consists of XML elements with attributes and subelements, possibly constrained
1956 by XML schema validation rules that enforce element and attribute occurrence
1957 contraints, numerical value range constraints, and string length and pattern
1958 constraints.
1959 
1960 Classes that are declared with the gSOAP tools are limited to single
1961 inheritence only. The soapcpp2 tool does not allow structs to be inherited.
1962 
1963 The class and struct name is bound to an XML namespace by means of the prefix
1964 naming convention or by using [colon notation](#toxsd1):
1965 
1966 ~~~{.cpp}
1967  //gsoap ns schema namespace: urn:types
1968  class ns__record
1969  {
1970  public:
1971  std::string name;
1972  uint64_t SSN;
1973  ns__record *spouse;
1974  ns__record();
1975  ~ns__record();
1976  protected:
1977  struct soap *soap;
1978  };
1979 ~~~
1980 
1981 In the example above, we also added a context pointer to the `soap` context that
1982 manages this instance. It is set when the instance is created in the engine's
1983 context, for example when deserialized and populated by the engine.
1984 
1985 The class maps to a complexType in the soapcpp2-generated XML schema:
1986 
1987 <div class="alt">
1988 ~~~{.xml}
1989  <complexType name="record">
1990  <sequence>
1991  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="1"/>
1992  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
1993  <element name="spouse" type="ns:record" minOccurs="0" maxOccurs="1" nillable="true"/>
1994  </sequence>
1995  </complexType>
1996 ~~~
1997 </div>
1998 
1999 The following sections apply to both structs and classes. Structs require the
2000 use of the `struct` keyword with the struct name, otherwise soapcpp2 will throw
2001 a syntax error. As is often done in C, use a `typedef` to declare a `struct`
2002 that can be used without the `struct` keyword.
2003 
2004 🔝 [Back to table of contents](#)
2005 
2006 ### Serializable versus transient types and data members {#toxsd9-1}
2007 
2008 Public data members of a class or struct are serializable when their types are
2009 serializable. Private and protected members are transient and not
2010 serializable.
2011 
2012 Also `const` and `static` members are not serializable, with the exception of
2013 `const char*` and `const wchar_t*`. Types and specific class/struct members
2014 can be made transient with the `extern` qualifier for types and by marking
2015 members with `[` and `]`:
2016 
2017 ~~~{.cpp}
2018  extern class std::ostream; // declare std::ostream transient
2019  class ns__record
2020  {
2021  public:
2022  [ int num; ] // not serialized: member is marked transient with [ ]
2023  std::ostream out; // not serialized: std:ostream is transient
2024  static const int MAX = 1024; // not serialized: static const member
2025  private:
2026  std::string id; // not serialized: private member
2027  };
2028 ~~~
2029 
2030 By declaring `std::ostream` transient with `extern` you can use this type
2031 wherever you need it without soapcpp2 complaining that this class and any other
2032 class or type declared as `extern` is not defined. Do not use `extern` with
2033 `typedef`, because this declares a custom serializer, see
2034 [adding custom serializers](#custom).
2035 
2036 Marking members transient with `[` and `]` makes them transient (and visually
2037 makes them stand out). This has otherwise no effect on the generated code for
2038 the class or struct to be used in your application code.
2039 
2040 🔝 [Back to table of contents](#)
2041 
2042 ### Derived types in C++ {#toxsd9-1-1}
2043 
2044 Extensible and restricted types in XML schemas are derived types from single
2045 simple and complex base types. XML schema derived types are naturally
2046 represented by C++ derived classes using single inheritance. Besides the
2047 concept of extensions versus restrictions, there are two kinds of derived
2048 types: complexTypes with simpleContent, meaning types with XML CDATA values,
2049 and complexTypes with complexContent, meaning types with sub-elements. Both
2050 are permitted to have one or more XML attributes.
2051 
2052 A complexType with simpleContent is defined as a wrapper to contain XML CDATA
2053 values and any number of attributes, see
2054 [wrapper class/struct with simpleContent](#toxsd10-4).
2055 Wrapper class/struct types can form a hierarchy of derived types in C++ using
2056 inheritance. For example:
2057 
2058 ~~~{.cpp}
2059  class xsd__anyType
2060  {
2061  public:
2062  std::string __item; // string to hold any simpleContent
2063  };
2064  class ns__data : public xsd__anyType
2065  {
2066  public:
2067  @ std::string value 1; // extends xsd:anyType with a required attribute
2068  };
2069 ~~~
2070 
2071 The `ns__data` class maps to a complexType in the soapcpp2-generated XML schema:
2072 
2073 <div class="alt">
2074 ~~~{.xml}
2075  <complexType name="string">
2076  <simpleContent>
2077  <extension base="xsd:string">
2078  <attribute name="value" type="xsd:string" use="required"/>
2079  </extension>
2080  </simpleContent>
2081  </complexType>
2082 ~~~
2083 </div>
2084 
2085 The XML value space consists of an element with the string contents an optional
2086 attribute:
2087 
2088 <div class="alt">
2089 ~~~{.xml}
2090  <ns:data value="abc">xyz</ns:data>
2091 ~~~
2092 </div>
2093 
2094 By contrast, a complexType with complexContent typically extends a given base
2095 complexType. For example:
2096 
2097 ~~~{.cpp}
2098  class ns__base
2099  {
2100  public:
2101  std::string name 1;
2102  int number 1;
2103  };
2104  class ns__derived : public ns__base
2105  {
2106  public:
2107  @ std::string value 1; // extends ns:base with an attribute
2108  std::string text 1; // extends ns:base with an element
2109  };
2110 ~~~
2111 
2112 The `ns__base` and `ns__derived` classes maps to complexTypes in the soapcpp2-generated XML schema:
2113 
2114 <div class="alt">
2115 ~~~{.xml}
2116  <complexType name="base">
2117  <sequence>
2118  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="1"/>
2119  <element name="number" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2120  </sequence>
2121  </complexType>
2122  <complexType name="derived">
2123  <complexContent>
2124  <extension base="ns:base">
2125  <sequence>
2126  <element name="text" type="xsd:string" minOccurs="1" maxOccurs="1"/>
2127  </sequence>
2128  </extension>
2129  </complexContent>
2130  <attribute name="value" type="xsd:string" use="required"/>
2131  </complexType>
2132 ~~~
2133 </div>
2134 
2135 The XML value space of `ns__derived` consists of three requires child elements
2136 and an optional attribute:
2137 
2138 <div class="alt">
2139 ~~~{.xml}
2140  <ns:derived value="abc">
2141  <name>def</name>
2142  <number>123</number>
2143  <text>xyz</text>
2144  </ns:derived>
2145 ~~~
2146 </div>
2147 
2148 Derived types can be used for two main purposes in XML schema by extending or
2149 restricting base types. One purpose is to reuse a base type when defining a
2150 derived type, such that common parts do not need to be replicated. The second
2151 purpose is to be able to use a derived type in place of a base type in XML, which
2152 is indicated by an <i>`xsi:type`</i> attribute with the qualified name of the
2153 derived type. Consider for example the following class that uses the
2154 previously declared base types `xsd__anyType` and `ns__base`:
2155 
2156 ~~~{.cpp}
2157  class ns__record
2158  {
2159  public:
2160  xsd__anyType *base1 1; // required element
2161  ns__base *base2 1; // required element
2162  };
2163 ~~~
2164 
2165 We can assign base type values to the `ns_record` members:
2166 
2167 ~~~{.cpp}
2168  ns__record record;
2169  record.base1 = soap_new_xsd__anyType(soap);
2170  record.base2 = soap_new_ns__base(soap);
2171  soap_write_ns__record(soap, &record);
2172 ~~~
2173 
2174 This produces the following XML fragment populated with default values (empty
2175 text for strings and zeros for numbers), where element <i>`base1`</i> has a
2176 simpleContent value and element <i>`base2`</i> has two child elements:
2177 
2178 <div class="alt">
2179 ~~~{.xml}
2180  <ns:record>
2181  <base1></base1>
2182  <base2>
2183  <name></name>
2184  <number>0</number>
2185  </base2>
2186  </ns:record>
2187 ~~~
2188 </div>
2189 
2190 We can also assign derived type values to the `ns_record` members:
2191 
2192 ~~~{.cpp}
2193  ns__record record;
2194  record.base1 = soap_new_ns__data(soap);
2195  record.base2 = soap_new_ns__derived(soap);
2196  soap_write_ns__record(soap, &record);
2197 ~~~
2198 
2199 This produces the following XML fragment populated with default values (empty
2200 text for strings and zeros for numbers), where element <i>`base1`</i> has
2201 schema type <i>`ns:data`</i> with simpleContent and an attribute, and
2202 <i>`base2`</i> has schema type <i>`ns:derived`</i> with three child elements
2203 and an attribute:
2204 
2205 <div class="alt">
2206 ~~~{.xml}
2207  <ns:record>
2208  <base1 xsi:type="ns:data" value=""></base1>
2209  <base2 xsi:type="ns:derived" value="">
2210  <name></name>
2211  <number>0</number>
2212  <text></text>
2213  </base2>
2214  </ns:record>
2215 ~~~
2216 </div>
2217 
2218 Deserialization automatically allocates and assigns a `ns__base` class instance to a
2219 `ns__base` pointer when deserializing the <i>`ns:base`</i> schema type and allocates and
2220 assigns a `ns__derived` class instance to a `ns__base` pointer when deserializing the
2221 <i>`ns:derived`</i> type when an element with <i>`xsi:type="ns:derived"`</i> is
2222 parsed. All classes are extended by soapcpp2 by a `soap_type()` method that
2223 returns the unique `SOAP_TYPE_T` value of the class `T`. This makes it easy to
2224 check whether the deserialized data contains a derived type to implement
2225 type-safe code, for example:
2226 
2227 ~~~{.cpp}
2228  ns__record record;
2229  soap_read_ns__record(soap, &record);
2230  if (record.base1->soap_type() == SOAP_TYPE_ns__data)
2231  std::cout << "Derived ns:data "
2232  << dynamic_cast<ns__data*>(record.base1)->value
2233  << std::endl;
2234  else
2235  std::cout << "Base xsd:anyType" << std::endl;
2236  if (record.base2->soap_type() == SOAP_TYPE_ns__derived)
2237  std::cout << "Derived ns:derived "
2238  << dynamic_cast<ns__derived*>(record.base2)->value
2239  << std::endl;
2240  else
2241  std::cout << "Base ns:base" << std::endl;
2242 ~~~
2243 
2244 This example should use the `SOAP_XML_STRICT` mode flag to initialize the
2245 `soap` context to ensure that all required values are present in the
2246 deserialized structures.
2247 
2248 🔝 [Back to table of contents](#)
2249 
2250 ### Derived types in C {#toxsd9-1-2}
2251 
2252 While single inheritance works well in C++ to represent derived types as we
2253 discussed in the previous section, this will obviously not work in C. Two
2254 methods to serialize derived types in C are presented here. The first method
2255 uses `void*` to serialize anything. The second method is more accurate and is
2256 relatively new in gSOAP.
2257 
2258 To serialize any type is possible with [tagged void pointer members](#toxsd9-12) to
2259 serialize data pointed to by a `void*` member, which can be any serializable
2260 type, such as derived types. For `void*` deserialization to work the XML
2261 parsed must contain an <i>`xsi:type`</i> attribute with a schema type. Only
2262 then can the deserializer instantiate the corresponding serializable C/C++
2263 type. Base types serialized do not require an <i>`xsi:type`</i> to indicate
2264 the base schema type, so this approach is not guaranteed to work and requires a
2265 workaround with an anonymous wrapper struct/class that contains both the base
2266 type and a `void*`. For example:
2267 
2268 ~~~{.cpp}
2269  struct ns__base // a base type
2270  {
2271  char *name 1;
2272  int number 1;
2273  };
2274  struct ns__derived // extends ns__base with two additional members
2275  {
2276  char *name 1;
2277  int number 1;
2278  char *text 1;
2279  @ char *value 1;
2280  };
2281  struct __ns__base // a wrapper, not visible in XML
2282  {
2283  int __type; // the SOAP_TYPE_T pointed to by __self
2284  void *__self; // points to any type
2285  struct ns__base *__self; // wraps ns__base for the current element tag
2286  }
2287  class ns__record
2288  {
2289  struct __ns__base base;
2290  };
2291 ~~~
2292 
2293 The `__ns__base` wrapper wraps the `ns__base` type to (de)serialize the
2294 <i>`base`</i> element that has no <i>`xsi:type`</i> attribute and uses `void*`
2295 to (de)serialize the <i>`base`</i> element that has <i>`xsi:type`</i>
2296 attribute. This works fine at the XML parsing level, but the generated
2297 XML schema components do not accurately represent the derived type, because it
2298 lacks the extension/restriction of the derived type (and the `__ns__base`
2299 wrapper is invisible).
2300 
2301 Using `void*` to represent derived types in a base type wrapper is not very
2302 accurate because we can serialize anything, not just derived types of a given
2303 base type. The wrapper may also hold two values: the base type value and a
2304 derived type value. Furthermore, using arrays or containers that hold base and
2305 derived types becomes quite tricky because an array item could hold both the
2306 base and derived type.
2307 
2308 As of gSOAP version 2.8.75, `wsdl2h -F` option `-F` generates base type structs
2309 extended with transient pointer members to its derived types. To serialize the
2310 base type itself, all of the pointer members are NULL. If one of the pointer
2311 members points to a derived type the derived type is serialized instead.
2312 Deserialization is automatic, in that the base type is deserialized if the
2313 element has no <i>`xsi:type`</i> attribute or the attribute is the base schema
2314 type, and a derived type is deserialized if the element has an
2315 <i>`xsi>type`</i> attribute with the derived schema type.
2316 
2317 This method is fully automated for the wsdl2h tool to generate an interface
2318 header file for soapcpp2 with the type derivations in C. To use this method to
2319 generate code from WSDLs and XSDs, use `wsdl2h -F` option `-F`. This also
2320 works in C++ if desired, but C++ inheritance works fine without this method.
2321 
2322 Using this method with soapcpp2 alone using a manually-specified interface
2323 header file produces the specified type inheritance in the soapcpp2-generated
2324 WSDL and XML schema files as complexType extensions.
2325 
2326 The soapcpp2 tool warns if a derived type has multiple base types. At most one
2327 base type for a derived type may be specified.
2328 
2329 This method with transient pointers to derived types makes it easy to use base
2330 and derived types in C:
2331 
2332 ~~~{.cpp}
2333  struct ns__base // a base type
2334  {
2335  char *name 1;
2336  int number 1;
2337  [ struct ns__derived *ns__derived; ] // points to derived type if non-NULL
2338  };
2339  struct ns__derived // extends ns__base with two additional members
2340  {
2341  char *name 1;
2342  int number 1;
2343  char *text 1;
2344  @ char *value 1;
2345  };
2346  struct ns__record
2347  {
2348  struct ns__base base; // contains base type or derived type value
2349  };
2350 ~~~
2351 
2352 The `ns__base` struct includes the special member `ns__derived` that points to
2353 a `ns__derived` value. This special member must be:
2354 
2355 - a transient member (i.e. non-serializable) by placing the declaration within
2356  `[` and `]`, and
2357 - the member name must match the type name (to be more precise, at least the
2358  initial part of the member name must match the type name as in the example
2359  `ns__derived_` works too).
2360 
2361 To serialize the `ns__base` value requires the `ns__derived` member to be NULL.
2362 To serialize the `ns__derived` value requires the `ns__derived` member to point
2363 to the `ns__derived` value to serialize and the `ns__base` members are
2364 irrelevant.
2365 
2366 We can assign the base type value to the `ns_record::base` member:
2367 
2368 ~~~{.cpp}
2369  struct ns__record record;
2370  soap_default_ns__record(soap, &record);
2371  soap_write_ns__record(soap, &record);
2372 ~~~
2373 
2374 This produces the following XML fragment populated with default values (empty
2375 text for strings and zeros for numbers), where element <i>`base`</i> has two
2376 child elements:
2377 
2378 <div class="alt">
2379 ~~~{.xml}
2380  <ns:record>
2381  <base>
2382  <name></name>
2383  <number>0</number>
2384  </base>
2385  </ns:record>
2386 ~~~
2387 </div>
2388 
2389 We can also assign the derived type value to the `ns_record::base` member:
2390 
2391 ~~~{.cpp}
2392  struct ns__record record;
2393  soap_default_ns__record(soap, &record);
2394  record.base.ns__derived = soap_new_ns__derived(soap, -1);
2395  soap_write_ns__record(soap, &record);
2396 ~~~
2397 
2398 This produces the following XML fragment populated with default values (empty
2399 text for strings and zeros for numbers), where element <i>`base`</i> has schema
2400 type <i>`ns:derived`</i> with three child elements and an attribute:
2401 
2402 <div class="alt">
2403 ~~~{.xml}
2404  <ns:record>
2405  <base xsi:type="ns:derived" value="">
2406  <name></name>
2407  <number>0</number>
2408  <text></text>
2409  </base>
2410  </ns:record>
2411 ~~~
2412 </div>
2413 
2414 Deserialization automatically assigns values to the base members for the
2415 `ns__base` type and populates the `ns__derived` member when a derived type with
2416 <i>`xsi:type="ns:derived"`</i> is parsed. This makes it easy to decompose the
2417 deserialized data:
2418 
2419 ~~~{.cpp}
2420  struct ns__record record;
2421  soap_read_ns__record(soap, &record);
2422  if (record.ns__derived)
2423  printf("Derived type with name=%s number=%d text=%s value=%s\n",
2424  record.ns__derived->name,
2425  record.ns__derived->number,
2426  record.ns__derived->text,
2427  record.ns__derived->value);
2428  else
2429  printf("Base type with name=%s number=%d\n",
2430  record.name,
2431  record.number);
2432 ~~~
2433 
2434 This example requires the `SOAP_XML_STRICT` mode flag to initialize the `soap`
2435 context to ensure that all required values are present in the deserialized
2436 structures, otherwise the `char*` strings may be NULL since XML validation
2437 constraints are not enforced on the XML input.
2438 
2439 Deeper levels of simulated inheritance are possible, for example:
2440 
2441 ~~~{.cpp}
2442  struct ns__base // a base type
2443  {
2444  char *name 1;
2445  int number 1;
2446  [ struct ns__derived *ns__derived; ] // points to derived type if non-NULL
2447  };
2448  struct ns__derived // extends ns__base with two additional members
2449  {
2450  char *name 1;
2451  int number 1;
2452  char *text 1;
2453  @ char *value 1;
2454  [ struct ns__derived_derived *ns__derived_derived; ] // points to derived_derived type if non-NULL
2455  };
2456  struct ns__derived_derived // extends ns__derived with an additional member
2457  {
2458  char *name 1;
2459  int number 1;
2460  char *text 1;
2461  @ char *value 1;
2462  @ char *type 1;
2463  };
2464 ~~~
2465 
2466 This requires two pointer traversals from the base type `ns__base` via
2467 `ns__derived` to reach `ns__derived_derived`.
2468 
2469 🔝 [Back to table of contents](#)
2470 
2471 ### Volatile classes and structs {#toxsd9-2}
2472 
2473 Classes and structs can be declared `volatile` in the interface header file for
2474 soapcpp2, which only has meaning for the gSOAP tools. This annotation means
2475 that these types are already declared elsewhere in your project's source code
2476 and you do not want soapcpp2 to generate code with a second declaration of
2477 these types.
2478 
2479 For example, `struct tm` is declared in the <i>`time.h`</i> library. You can
2480 make it serializable and include a partial list of data members that you want
2481 to serialize:
2482 
2483 ~~~{.cpp}
2484  volatile struct tm
2485  {
2486  int tm_sec; // seconds (0 - 60)
2487  int tm_min; // minutes (0 - 59)
2488  int tm_hour; // hours (0 - 23)
2489  int tm_mday; // day of month (1 - 31)
2490  int tm_mon; // month of year (0 - 11)
2491  int tm_year; // year - 1900
2492  };
2493 ~~~
2494 
2495 You can declare classes and structs `volatile` for any such types you want to
2496 serialize by only providing the public data members you want to serialize.
2497 
2498 In addition, [colon notation](#toxsd2) is a simple and effective way to bind an
2499 existing class or struct to a schema. For example, you can change the `tm` name
2500 as follows without affecting the code that uses `struct tm` generated by
2501 soapcpp2:
2502 
2503 ~~~{.cpp}
2504  volatile struct ns:tm { ... }
2505 ~~~
2506 
2507 This struct maps to a complexType in the soapcpp2-generated XML schema:
2508 
2509 <div class="alt">
2510 ~~~{.xml}
2511  <complexType name="tm">
2512  <sequence>
2513  <element name="tm-sec" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2514  <element name="tm-min" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2515  <element name="tm-hour" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2516  <element name="tm-mday" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2517  <element name="tm-mon" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2518  <element name="tm-year" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2519  </sequence>
2520  </complexType>
2521 ~~~
2522 </div>
2523 
2524 🔝 [Back to table of contents](#)
2525 
2526 ### Mutable classes and structs {#toxsd9-3}
2527 
2528 Classes and structs can be declared `mutable` with the gSOAP tools. This means
2529 that their definition can be spread out over the source code. This promotes the
2530 concept of a class or struct as a *row of named values*, also known as a *named
2531 tuple*, that can be extended at compile time in your source code with additional
2532 members. Because these types differ from the traditional object-oriented
2533 principles and design concepts of classes and objects, constructors and
2534 destructors cannot be defined (also because we cannot guarantee merging these
2535 into one such that all members will be initialized). A default constructor,
2536 copy constructor, assignment operation, and destructor will be assigned
2537 automatically by soapcpp2.
2538 
2539 ~~~{.cpp}
2540  mutable struct ns__tuple
2541  {
2542  @ std::string id;
2543  };
2544 
2545  mutable struct ns__tuple
2546  {
2547  std::string name;
2548  std::string value;
2549  };
2550 ~~~
2551 
2552 The members are collected into one definition generated by soapcpp2. Members
2553 may be repeated from one definition to another, but only if their associated
2554 types are identical. So, for example, a third extension with a `value` member
2555 with a different type fails:
2556 
2557 ~~~{.cpp}
2558  mutable struct ns__tuple
2559  {
2560  float value; // BAD: value is already declared std::string
2561  };
2562 ~~~
2563 
2564 The `mutable` concept has proven to be very useful when declaring and
2565 collecting SOAP Headers for multiple services, which are collected into one
2566 `struct SOAP_ENV__Header` by the soapcpp2 tool.
2567 
2568 🔝 [Back to table of contents](#)
2569 
2570 ### Default and fixed member values {#toxsd9-4}
2571 
2572 Class and struct data members in C and C++ may be declared with an optional
2573 default initialization value that is provided "inline" with the declaration of
2574 the member:
2575 
2576 ~~~{.cpp}
2577  class ns__record
2578  {
2579  public:
2580  std::string name = "Joe";
2581  ...
2582  };
2583 ~~~
2584 
2585 Alternatively, you can use C++11 default initialization syntax:
2586 
2587 ~~~{.cpp}
2588  class ns__record
2589  {
2590  public:
2591  std::string name { "Joe" };
2592  ...
2593  };
2594 ~~~
2595 
2596 Any member with a primitive type can be initialized in this way.
2597 
2598 These initializations are performed by the default constructor that is added by
2599 soapcpp2 to each class and struct (in C++ only). A constructor is only added
2600 when a default constructor is not already defined with the class declaration.
2601 
2602 You can explicitly (re)initialize an object with these initial values by using
2603 the soapcpp2 auto-generated functions:
2604 
2605 - `void T::soap_default(struct soap*)` for `class T` (C++ only)
2606 
2607 - `void soap_default_T(struct soap*, T*)` for `struct T` (C and C++).
2608 
2609 If `T` is a struct or class that has a `soap` pointer member to a `::soap`
2610 context then this pointer member will be set to the first argument passed to
2611 these functions to initialize their `soap` pointer member.
2612 
2613 Default value initializations can be provided for members that have primitive
2614 types (`bool`, `enum`, `time_t`, numeric and string types).
2615 
2616 Default value initializations of pointer members is permitted, but the effect
2617 is different. To conform to XML schema validation, an attribute member that is
2618 a pointer to a primitive type will be assigned the default value when parsed
2619 from XML. An element member that is a pointer to a primitive type will be
2620 assigned when the element is empty when parsed from XML.
2621 
2622 As of gSOAP 2.8.48 and greater, a fixed value can be assigned with a `==`. A
2623 fixed value is also verified by the parser's validator.
2624 
2625 Default and fixed values for members with or without pointers are best
2626 explained with the following two example fragments.
2627 
2628 A record class with default values for `std::string` (or `std::wstring`)
2629 attributes and elements is declared as follows:
2630 
2631 ~~~{.cpp}
2632  class ns__record_with_default
2633  {
2634  public:
2635  @ std::string a = "A"; // optional XML attribute with default value "A"
2636  @ std::string b 1 = "B"; // required XML attribute with default value "B"
2637  @ std::string *c = "C"; // optional XML attribute with default value "C"
2638  std::string d 0 = "D"; // optional XML element with default value "D"
2639  std::string e = "E"; // required XML element with default value "E"
2640  std::string *f = "F"; // optional XML element with default value "F"
2641  ...
2642  };
2643 ~~~
2644 
2645 Also `std::unique_ptr` and `std::shared_ptr` may be used instead of a regular
2646 pointer to strings.
2647 
2648 With C `char*` (or `const char*`, `const wchar_t*`) strings in a struct, this
2649 becomes:
2650 
2651 ~~~{.cpp}
2652  struct ns__record_with_default
2653  {
2654  @ char* a = "A"; // optional XML attribute with default value "A"
2655  @ char* b 1 = "B"; // required XML attribute with default value "B"
2656  char* e 1 = "E"; // required XML element with default value "E"
2657  char* f = "F"; // optional XML element with default value "F"
2658  ...
2659  };
2660 ~~~
2661 
2662 By contrast to `std::string e`, `char* e` must be marked `1` to make it
2663 required, because pointer members are optional by default.
2664 
2665 Attributes are considered optional by default, unless marked as required with
2666 the occurrence constraint `1`. Elements are considered required unless the
2667 member type is a pointer or if the member is marked optional with occurrence
2668 constraint `0`.
2669 
2670 Instead of default values, fixed values indicate that the attribute or element
2671 must contain that value, and only that value, when provided in XML. A fixed
2672 value is specified with a `==`.
2673 
2674 Attributes with default or fixed values may be omitted in XML. When absent,
2675 the default/fixed value is used at the receiving side, i.e. the deserializer
2676 assigns the default/fixed value when the attribute is absent. Therefore, there
2677 is no need to make attributes with default/fixed values pointer based, because
2678 there is no way to distinguish an omitted attribute from a populated attribute
2679 on the receiving side. The `c` member in the example above can be a
2680 non-pointer for this reason. The wsdl2h tool does not generate pointers for
2681 attributes with default/fixed values.
2682 
2683 Elements with default or fixed values may be optional and the use of
2684 default/fixed values with elements differs from attributes. The default/fixed
2685 value of an element is only used for elements that are empty in the XML payload
2686 received. Omitted optional elements in the XML payload received are simply
2687 absent; no default/fixed value is assigned.
2688 
2689 @note gSOAP 2.8.106 and greater treat `char*` and `wchar_t*` with explicit
2690 default and fixed values differently than previous versions. Versions prior to
2691 2.8.106 assign the default value when the corresponding XML element is absent,
2692 whereas 2.8.106 and greater assign NULL when the XML element is absent, exactly
2693 as documented in this updated version of this document. To revert to the old
2694 behavior, use <b>`soapcpp2 -z4`</b> option <b>`-z4`</b>. The change affects
2695 members `char* f` and `char* l` (see below).
2696 
2697 A record class (can be a struct in C) with fixed values for attributes and
2698 elements is declared as follows:
2699 
2700 ~~~{.cpp}
2701  class ns__record_with_fixed
2702  {
2703  public:
2704  @ std::string g == "G"; // optional XML attribute with fixed value "G"
2705  @ std::string h 1 == "H"; // required XML attribute with fixed value "H"
2706  @ std::string *i == "I"; // optional XML attribute with fixed value "I"
2707  std::string j 0 == "J"; // optional XML element with fixed value "J"
2708  std::string k == "K"; // required XML element with fixed value "K"
2709  std::string *l == "L"; // optional XML element with fixed value "L"
2710  ...
2711  };
2712 ~~~
2713 
2714 With C `char*` (or `const char*`, `const wchar_t*`) strings in a struct, this
2715 becomes:
2716 
2717 ~~~{.cpp}
2718  struct ns__record_with_fixed
2719  {
2720  @ char* g == "G"; // optional XML attribute with fixed value "G"
2721  @ char* h 1 == "H"; // required XML attribute with fixed value "H"
2722  char* k 1 == "K"; // required XML element with fixed value "K"
2723  char* l == "L"; // optional XML element with fixed value "L"
2724  ...
2725  };
2726 ~~~
2727 
2728 The XML schema validation rules for the examples above are as follows:
2729 
2730 Member | Notes
2731 ------ | ---------------------------------------------------------------------
2732 `a` | attribute may appear once; if it does not appear its value is "A", otherwise its value is that given (also note: instantiating `ns__record_with_default` assigns the default value "A")
2733 `b` | has no effect when parsing XML (but note: instantiating `ns__record_with_default` assigns the default value "B")
2734 `c` | attribute may appear once; if it does not appear its value is "C", otherwise its value is that given (also note: instantiating `ns__record_with_default` assigns NULL)
2735 `d` | element may appear once; if it does not appear or if it is empty, its value is "D"; otherwise its value is that given (also note: instantiating `ns__record_with_default` assigns the default value "D")
2736 `e` | has no effect when parsing XML (but note: instantiating `ns__record_with_default` assigns the default value "E")
2737 `f` | element may appear once; if it does not appear it is not provided; if it does appear and it is empty, its value is "F"; otherwise its value is that given (also note: instantiating `ns__record_with_default` assigns NULL)
2738 `g` | attribute may appear once; if it does not appear its value is "G", if it does not appear its value is "G" (also note: instantiating `ns__record_with_fixed` assigns the fixed value "G")
2739 `h` | attribute must appear once, its value must be "H" (also note: instantiating `ns__record_with_fixed` assigns the fixed value "H")
2740 `i` | attribute may appear once; if it does not appear its value is "I", if it does not appear its value is "I" (also note: instantiating `ns__record_with_fixed` assigns NULL)
2741 `j` | element may appear once, if it does not appear it is not provided; if it does appear and it is empty, its value is "J"; if it does appear and it is not empty, its value must be "J" (also note: instantiating `ns__record_with_fixed` assigns the fixed value "J")
2742 `k` | element must appear once, its value must be "K" (also note: instantiating `ns__record_with_fixed` assigns the fixed value "K")
2743 `l` | element may appear once, if it does not appear it is not provided; if it does appear and it is empty, its value is "J"; if it does appear and it is not empty, its value must be "J" (also note: instantiating `ns__record_with_fixed` assigns NULL)
2744 
2745 Members of type `char[N]` (fixed length string) can have default and fixed
2746 values, when <b>`soapcpp2 -b`</b> option <b>`-b`</b> is used. Also `char**`
2747 (pointer to a string) members can have default and fixed values. However,
2748 members of this type will be initialized to NULL. The default/fixed values
2749 will be assigned with the same rules as for `char*` when deserialized from XML.
2750 
2751 @see Section [operations on classes and structs](#toxsd9-14).
2752 
2753 🔝 [Back to table of contents](#)
2754 
2755 ### Attribute members {#toxsd9-5}
2756 
2757 Class and struct data members are declared as XML attributes by annotating
2758 their type with a `@` qualifier:
2759 
2760 ~~~{.cpp}
2761  class ns__record
2762  {
2763  public:
2764  @ std::string name; // required (non-pointer means required)
2765  @ uint64_t SSN; // required (non-pointer means required)
2766  ns__record *spouse; // optional (pointer means minOccurs=0)
2767  };
2768 ~~~
2769 
2770 This class maps to a complexType in the soapcpp2-generated XML schema:
2771 
2772 <div class="alt">
2773 ~~~{.xml}
2774  <complexType name="record">
2775  <sequence>
2776  <element name="spouse" type="ns:record" minOccurs="0" maxOccurs="1" nillable="true"/>
2777  </sequence>
2778  <attribute name="name" type="xsd:string" use="required"/>
2779  <attribute name="SSN" type="xsd:unsignedLong" use="required"/>
2780  </complexType>
2781 ~~~
2782 </div>
2783 
2784 An example XML instance of `ns__record` is:
2785 
2786 <div class="alt">
2787 ~~~{.xml}
2788  <ns:record xmlns:ns="urn:types" name="Joe" SSN="1234567890">
2789  <spouse name="Jane" SSN="1987654320">
2790  </spouse>
2791  </ns:record>
2792 ~~~
2793 </div>
2794 
2795 Attribute data members are restricted to primitive types (`bool`, `enum`,
2796 `time_t`, numeric and string types), `xsd__hexBinary`, `xsd__base64Binary`, and
2797 custom serializers, such as `xsd__dateTime`. Custom serializers for types that
2798 may be used as attributes should define `soap_s2T` and `soap_T2s` functions that
2799 convert values of type `T` to strings and back.
2800 
2801 Attribute data members can be pointers and smart pointers to these types, which
2802 permits attributes to be optional.
2803 
2804 🔝 [Back to table of contents](#)
2805 
2806 ### Backtick XML tags {#toxsd9-5-1}
2807 
2808 The XML tag name of a class/struct member is the name of the member with the
2809 usual XML tag translation, see [colon notation](#toxsd2).
2810 
2811 To override the standard translation of identifier names to XML tag names of
2812 attributes and elements, add the XML tag name in backticks (requires gSOAP
2813 2.8.30 or greater):
2814 
2815 ~~~{.cpp}
2816  class ns__record
2817  {
2818  public:
2819  @ std::string name `full-name`;
2820  @ uint64_t SSN `tax-id`;
2821  ns__record *spouse `married-to`;
2822  };
2823 ~~~
2824 
2825 This class maps to a complexType in the soapcpp2-generated XML schema:
2826 
2827 <div class="alt">
2828 ~~~{.xml}
2829  <complexType name="record">
2830  <sequence>
2831  <element name="married-to" type="ns:record" minOccurs="0" maxOccurs="1"/>
2832  </sequence>
2833  <attribute name="full-name" type="xsd:string" use="required"/>
2834  <attribute name="tax-id" type="xsd:unsignedLong" use="required"/>
2835  </complexType>
2836 ~~~
2837 </div>
2838 
2839 An example XML instance of `ns__record` is:
2840 
2841 <div class="alt">
2842 ~~~{.xml}
2843  <ns:record xmlns:ns="urn:types" full-name="Joe" tax-id="1234567890">
2844  <married-to full-name="Jane" tax-id="1987654320">
2845  </married-to>
2846  </ns:record>
2847 ~~~
2848 </div>
2849 
2850 A backtick XML tag name may contain any non-empty sequence of ASCII and UTF-8
2851 characters except white space and the backtick character. A backtick tag can
2852 be combined with member constraints and default member initializers:
2853 
2854 ~~~{.cpp}
2855  @ uint64_t SSN `tax-id` 0:1 = 999;
2856 ~~~
2857 
2858 🔝 [Back to table of contents](#)
2859 
2860 ### Qualified and unqualified members {#toxsd9-6}
2861 
2862 Class, struct, and union data members are mapped to namespace qualified or
2863 unqualified tag names of local elements and attributes. If a data member has
2864 no prefix then the default form of qualification is applied based on the
2865 element/attribute form that is declared with the XML schema of the class, struct,
2866 or union type. If the member name has a namespace prefix by colon notation,
2867 then the prefix overrules the default (un)qualified form. Therefore,
2868 [colon notation](#toxsd2) is an effective mechanism to control qualification of
2869 tag names of individual members of classes, structs, and unions.
2870 
2871 The XML schema elementFormDefault and attributeFormDefault declarations control
2872 the tag name qualification of local elements and attributes, respectively.
2873 
2874 - "unqualified" indicates that local elements/attributes are not qualified with
2875  the namespace prefix.
2876 
2877 - "qualified" indicates that local elements/attributes must be qualified with
2878  the namespace prefix.
2879 
2880 Individual schema declarations of local elements and attributes may overrule
2881 this by using the form declaration in an XML schema and by using colon notation
2882 to add namespace prefixes to class, struct, and union members in the header
2883 file for soapcpp2.
2884 
2885 Consider for example an `ns__record` class in the `ns` namespace in which local
2886 elements are qualified and local attributes are unqualified by default:
2887 
2888 ~~~{.cpp}
2889  //gsoap ns schema namespace: urn:types
2890  //gsoap ns schema elementForm: qualified
2891  //gsoap ns schema attributeForm: unqualified
2892  class ns__record
2893  {
2894  public:
2895  @ std::string name;
2896  @ uint64_t SSN;
2897  ns__record *spouse;
2898  };
2899 ~~~
2900 
2901 This class maps to a complexType in the soapcpp2-generated XML schema with
2902 targetNamespace "urn:types", elementFormDefault qualified and
2903 attributeFormDefault unqualified:
2904 
2905 <div class="alt">
2906 ~~~{.xml}
2907  <schema targetNamespace="urn:types"
2908  ...
2909  elementFormDefault="qualified"
2910  attributeFormDefault="unqualified"
2911  ... >
2912  <complexType name="record">
2913  <sequence>
2914  <element name="spouse" type="ns:record" minOccurs="0" maxOccurs="1"/>
2915  </sequence>
2916  <attribute name="name" type="xsd:string" use="required"/>
2917  <attribute name="SSN" type="xsd:unsignedLong" use="required"/>
2918  </complexType>
2919  </schema>
2920 ~~~
2921 </div>
2922 
2923 An example XML instance of `ns__record` is:
2924 
2925 <div class="alt">
2926 ~~~{.xml}
2927  <ns:record xmlns:ns="urn:types" name="Joe" SSN="1234567890">
2928  <ns:spouse> name="Jane" SSN="1987654320">
2929  </ns:spouse>
2930  </ns:record>
2931 ~~~
2932 </div>
2933 
2934 Here the root element <i>`<ns:record>`</i> is qualified because it is a root
2935 element of the XML schema with target namespace "urn:types". Its local element
2936 <i>`<ns:spouse>`</i> is namespace qualified because the elementFormDefault of
2937 local elements is qualified. Attributes are unqualified.
2938 
2939 The default namespace (un)qualification of local elements and attributes can be
2940 overruled by adding a prefix to the member name by using colon notation:
2941 
2942 ~~~{.cpp}
2943  //gsoap ns schema namespace: urn:types
2944  //gsoap ns schema elementForm: qualified
2945  //gsoap ns schema attributeForm: unqualified
2946  class ns__record
2947  {
2948  public:
2949  @ std::string ns:name; // 'ns:' qualified
2950  @ uint64_t SSN;
2951  ns__record *:spouse; // ':' unqualified (empty prefix)
2952  };
2953 ~~~
2954 
2955 The colon notation for member <i>`ns:name`</i> forces qualification of its attribute
2956 tag in XML. The colon notation for member <i>`:spouse`</i> removes qualification from
2957 its local element tag:
2958 
2959 <div class="alt">
2960 ~~~{.xml}
2961  <schema targetNamespace="urn:types"
2962  ...
2963  elementFormDefault="unqualified"
2964  attributeFormDefault="unqualified"
2965  ... >
2966  <complexType name="record">
2967  <sequence>
2968  <element name="spouse" type="ns:record" minOccurs="0" maxOccurs="1" form="unqualified"/>
2969  </sequence>
2970  <attribute name="name" type="xsd:string" use="required" form="qualified"/>
2971  <attribute name="SSN" type="xsd:unsignedLong" use="required"/>
2972  </complexType>
2973  </schema>
2974 ~~~
2975 </div>
2976 
2977 XML instances of `ns__record` have unqualified spouse elements and qualified
2978 ns:name attributes:
2979 
2980 <div class="alt">
2981 ~~~{.xml}
2982  <ns:record xmlns:ns="urn:types" ns:name="Joe" SSN="1234567890">
2983  <spouse> ns:name="Jane" SSN="1987654320">
2984  </spouse>
2985  </ns:record>
2986 ~~~
2987 </div>
2988 
2989 Members of a class or struct can also be prefixed using the `prefix__name`
2990 convention or using colon notation `prefix:name`. However, this has a
2991 different effect by referring to global (root) elements and attributes, see
2992 [document root element definitions](#toxsd9-7).
2993 
2994 [Backtick XML tags](#toxsd9-5-1) can be used in place of the member name
2995 annotations and will achieve the same effect as described when these tag names
2996 are (un)qualified (requires gSOAP 2.8.30 or greater).
2997 
2998 @note You must declare a target namespace with a `//gsoap ns schema namespace:`
2999 directive to enable the `elementForm` and `attributeForm` directives in order
3000 to generate valid XML schemas with soapcpp2. See [directives](#directives) for
3001 more details.
3002 
3003 🔝 [Back to table of contents](#)
3004 
3005 ### Defining document root elements {#toxsd9-7}
3006 
3007 To define and reference XML document root elements we use type names that start
3008 with an underscore:
3009 
3010 ~~~{.cpp}
3011  class _ns__record
3012 ~~~
3013 
3014 Alternatively, we can use a `typedef` to define a document root element with a
3015 given type:
3016 
3017 ~~~{.cpp}
3018  typedef ns__record _ns__record;
3019 ~~~
3020 
3021 This `typedef` maps to a global root element that is added to the
3022 soapcpp2-generated XML schema:
3023 
3024 <div class="alt">
3025 ~~~{.xml}
3026  <element name="record" type="ns:record"/>
3027 ~~~
3028 </div>
3029 
3030 An example XML instance of `_ns__record` is:
3031 
3032 <div class="alt">
3033 ~~~{.xml}
3034  <ns:record xmlns:ns="urn:types">
3035  <name>Joe</name>
3036  <SSN>1234567890</SSN>
3037  <spouse>
3038  <name>Jane</name>
3039  <SSN>1987654320</SSN>
3040  </spouse>
3041  </ns:record>
3042 ~~~
3043 </div>
3044 
3045 Global-level element/attribute definitions are also referenced and/or added to
3046 the generated XML schema when serializable data members reference these by
3047 their qualified name:
3048 
3049 ~~~{.cpp}
3050  typedef std::string _ns__name 1 : 100;
3051  class _ns__record
3052  {
3053  public:
3054  @ _QName xsi__type; // built-in XSD attribute xsi:type
3055  _ns__name ns__name; // ref to global ns:name element
3056  uint64_t SSN;
3057  _ns__record *spouse;
3058  };
3059 ~~~
3060 
3061 These types map to the following comonents in the soapcpp2-generated XML
3062 schema:
3063 
3064 <div class="alt">
3065 ~~~{.xml}
3066  <simpleType name="name">
3067  <restriction base="xsd:string">
3068  <minLength value="1"/>
3069  <maxLength value="100"/>
3070  </restriction>
3071  </simpleType>
3072  <element name="name" type="ns:name"/>
3073  <complexType name="record">
3074  <sequence>
3075  <element ref="ns:name" minOccurs="1" maxOccurs="1"/>
3076  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3077  <element name="spouse" type="ns:record" minOccurs="0" maxOccurs="1"/>
3078  </sequence>
3079  <attribute ref="xsi:type" use="optional"/>
3080  </complexType>
3081  <element name="record" type="ns:record"/>
3082 ~~~
3083 </div>
3084 
3085 Use only use qualified member names when their types match the global-level
3086 element types that they refer to. For example:
3087 
3088 ~~~{.cpp}
3089  typedef std::string _ns__name; // global element ns:name of type xsd:string
3090  class _ns__record
3091  {
3092  public:
3093  int ns__name; // BAD: global element ns:name is NOT type int
3094  _ns__record ns__record; // OK: ns:record is a global-level root element
3095  ...
3096  };
3097 ~~~
3098 
3099 Therefore, we recommend to use qualified member names only when necessary to
3100 refer to standard XSD elements and attributes, such as `xsi__type`, and
3101 `xsd__lang`.
3102 
3103 By contrast, colon notation has the desired effect to (un)qualify local tag
3104 names by overruling the default element/attribute namespace qualification, see
3105 [qualified and unqualified members](#toxsd9-6).
3106 
3107 As an alternative to prefixing member names, use the backtick tag (requires
3108 gSOAP 2.8.30 or greater):
3109 
3110 ~~~{.cpp}
3111  typedef std::string _ns__name 1 : 100;
3112  class _ns__record
3113  {
3114  public:
3115  @ _QName t <i>`xsi:type`</i>; // built-in XSD attribute xsi:type
3116  _ns__name s <i>`ns:name`</i>; // ref to global ns:name element
3117  uint64_t SSN;
3118  _ns__record *spouse;
3119  };
3120 ~~~
3121 
3122 🔝 [Back to table of contents](#)
3123 
3124 ### (Smart) pointer members and their occurrence constraints {#toxsd9-8}
3125 
3126 A public pointer-typed data member is serialized by following its (smart)
3127 pointer(s) to the value pointed to. To serialize pointers to dynamic arrays of
3128 data, please see the next section on
3129 [container and array members and their occurrence constraints](#toxsd9-9).
3130 
3131 Pointers that are NULL and smart pointers that are empty are serialized to
3132 produce omitted element and attribute values, unless an element is required
3133 and is nillable (struct/class members marked with `nullptr`) in which case the
3134 element is rendered as an empty element with <i>`xsi:nil="true"`</i>.
3135 
3136 To control the occurrence requirements of pointer-based data members,
3137 occurrence constraints are associated with data members in the form of a range
3138 `minOccurs : maxOccurs`. For non-repeatable (meaning, not a container or array)
3139 data members, there are only three reasonable occurrence constraints:
3140 
3141 - `0:0` means that this element or attribute is prohibited.
3142 
3143 - `0:1` means that this element or attribute is optional.
3144 
3145 - `1:1` means that this element or attribute is required.
3146 
3147 Pointer-based data members have a default `0:1` occurrence constraint, making
3148 them optional, and their XML schema local element/attribute definition is
3149 marked as nillable. Non-pointer data members have a default `1:1` occurence
3150 constraint, making them required.
3151 
3152 A `nullptr` occurrence constraint may be applicable to required elements that
3153 are nillable pointer types, thus `nullptr 1:1`. This indicates that the
3154 element is nillable (can be `NULL` or `nullptr`). A pointer data member that
3155 is explicitly marked as required and nillable with `nullptr 1:1` will be
3156 serialized as an element with an <i>`xsi:nil`</i> attribute, thus effectively
3157 revealing the NULL property of its value.
3158 
3159 A non-pointer data member that is explicitly marked as optional with `0:1` will
3160 be set to its default value when no XML value is presented to the deserializer.
3161 A default value can be assigned to a data member that has a primitive type or
3162 is a (smart) pointer to primitive type.
3163 
3164 Consider for example:
3165 
3166 ~~~{.cpp}
3167  class ns__record
3168  {
3169  public:
3170  std::shared_ptr<std::string> name; // optional (pointer means minOccurs=0)
3171  uint64_t SSN 0:1 = 999; // force optional with default 999
3172  ns__record *spouse nullptr 1:1; // force required and nillabe when absent
3173  };
3174 ~~~
3175 
3176 This class maps to a complexType in the soapcpp2-generated XML schema:
3177 
3178 <div class="alt">
3179 ~~~{.xml}
3180  <complexType name="record">
3181  <sequence>
3182  <element name="name" type="xsd:string" minOccurs="0" maxOccurs="1" nillable="true"/>
3183  <element name="SSN" type="xsd:unsignedLong" minOccurs="0" maxOccurs="1" default="999"/>
3184  <element name="spouse" type="ns:record" minOccurs="1" maxOccurs="1" nillable="true"/>
3185  </sequence>
3186  </complexType>
3187 ~~~
3188 </div>
3189 
3190 An example XML instance of `ns__record` with its `name` string value set to
3191 `Joe`, `SSN` set to its default, and `spouse` set to NULL:
3192 
3193 <div class="alt">
3194 ~~~{.xml}
3195  <ns:record xmlns:ns="urn:types" ...>
3196  <name>Joe</name>
3197  <SSN>999</SSN>
3198  <spouse xsi:nil="true"/>
3199  </ns:record>
3200 ~~~
3201 </div>
3202 
3203 @note In general, a smart pointer is simply declared as a `volatile` template
3204 in a interface header file for soapcpp2:
3205 ~~~{.cpp}
3206  volatile template <class T> class NAMESPACE::shared_ptr;
3207 ~~~
3208 
3209 @note The soapcpp2 tool generates code that uses `NAMESPACE::shared_ptr` and
3210 `NAMESPACE::make_shared` to create shared pointers to objects, where
3211 `NAMESPACE` is any valid C++ namespace such as `std` and `boost` if you have
3212 Boost installed.
3213 
3214 🔝 [Back to table of contents](#)
3215 
3216 ### Container and array members and their occurrence constraints {#toxsd9-9}
3217 
3218 Class and struct data member types that are containers `std::deque`,
3219 `std::list`, `std::vector` and `std::set` are serialized as a collection of
3220 the values they contain. You can also serialize dynamic arrays, which is the
3221 alternative for C to store collections of data. Let's start with STL containers.
3222 
3223 You can use `std::deque`, `std::list`, `std::vector`, and `std::set` containers
3224 by importing:
3225 
3226 ~~~{.cpp}
3227  #import "import/stl.h" // import all containers
3228  #import "import/stldeque.h" // import deque
3229  #import "import/stllist.h" // import list
3230  #import "import/stlvector.h" // import vector
3231  #import "import/stlset.h" // import set
3232 ~~~
3233 
3234 For example, to use a vector data mamber to store names in a record:
3235 
3236 ~~~{.cpp}
3237  #import "import/stlvector.h"
3238  class ns__record
3239  {
3240  public:
3241  std::vector<std::string> names;
3242  uint64_t SSN;
3243  };
3244 ~~~
3245 
3246 To limit the number of names in the vector within reasonable bounds, occurrence
3247 constraints are associated with the container. Occurrence constraints are of
3248 the form `minOccurs : maxOccurs`:
3249 
3250 ~~~{.cpp}
3251  #import "import/stlvector.h"
3252  class ns__record
3253  {
3254  public:
3255  std::vector<std::string> names 1:10;
3256  uint64_t SSN;
3257  };
3258 ~~~
3259 
3260 This class maps to a complexType in the soapcpp2-generated XML schema:
3261 
3262 <div class="alt">
3263 ~~~{.xml}
3264  <complexType name="record">
3265  <sequence>
3266  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="10"/>
3267  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3268  </sequence>
3269  </complexType>
3270 ~~~
3271 </div>
3272 
3273 @note In general, a container is simply declared as a template in an interface
3274 header file for soapcpp2. All class templates are considered containers
3275 (except when declared `volatile`, see smart pointers). For example,
3276 `std::vector` is declared in <i>`gsoap/import/stlvector.h`</i> as:
3277 ~~~{.cpp}
3278  template <class T> class std::vector;
3279 ~~~
3280 
3281 @note You can define and use your own containers. The soapcpp2 tool generates
3282 code that uses the following members of the `template <typename T> class C`
3283 container:
3284 ~~~{.cpp}
3285  void C::clear()
3286  C::iterator C::begin()
3287  C::const_iterator C::begin() const
3288  C::iterator C::end()
3289  C::const_iterator C::end() const
3290  size_t C::size() const
3291  C::iterator C::insert(C::iterator pos, const T& val)
3292 ~~~
3293 
3294 @note For more details see the example `simple_vector` container with
3295 documentation in the package under <i>`gsoap/samples/template`</i>.
3296 
3297 Because C does not support a container template library, we can use a
3298 dynamically-sized array of values. This array is declared as a size-pointer
3299 pair of members within a struct or class. The array size information is stored
3300 in a special size tag member with the name `__size` or `__sizeX`, where `X` can
3301 be any name, or by an `$int` member to identify the member as a special size
3302 tag:
3303 
3304 ~~~{.cpp}
3305  struct ns__record
3306  {
3307  $ int sizeofnames; // array size
3308  char* *names; // array of char* names
3309  uint64_t SSN;
3310  };
3311 ~~~
3312 
3313 This struct maps to a complexType in the soapcpp2-generated XML schema:
3314 
3315 <div class="alt">
3316 ~~~{.xml}
3317  <complexType name="record">
3318  <sequence>
3319  <element name="name" type="xsd:string" minOccurs="0" maxOccurs="unbounded" nillable="true"/>
3320  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3321  </sequence>
3322  </complexType>
3323 ~~~
3324 </div>
3325 
3326 To limit the number of names in the array within reasonable bounds, occurrence
3327 constraints are associated with the array size member. Occurrence constraints
3328 are of the form `minOccurs : maxOccurs`:
3329 
3330 ~~~{.cpp}
3331  struct ns__record
3332  {
3333  $ int sizeofnames 1:10; // array size 1..10
3334  char* *names; // array of one to ten char* names
3335  uint64_t SSN;
3336  };
3337 ~~~
3338 
3339 This struct maps to a complexType in the soapcpp2-generated XML schema:
3340 
3341 <div class="alt">
3342 ~~~{.xml}
3343  <complexType name="record">
3344  <sequence>
3345  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="10" nillable="true"/>
3346  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3347  </sequence>
3348  </complexType>
3349 ~~~
3350 </div>
3351 
3352 Arrays can also be declared as nested elements, similar to SOAP-encoded dynamic arrays, and these arrays can be used with or without SOAP applications. This requires a separate struct or class with the name of the SOAP array, which should not be qualified with a namespace prefix:
3353 
3354 ~~~{.cpp}
3355  struct ArrayOfstring
3356  {
3357  char* *__ptr 1:100; // array of 1..100 strings
3358  int __size; // array size
3359  };
3360  struct ns__record
3361  {
3362  struct ArrayOfstring names; // array of char* names
3363  uint64_t SSN;
3364  };
3365 ~~~
3366 
3367 The `ns__record` struct maps to a complexType that references the <i>`ArrayOfstring`</i> complexType with an sequence of 1 to 100 <i>`item`</i> elements:
3368 
3369 <div class="alt">
3370 ~~~{.xml}
3371  <complexType name="ArrayOfstring">
3372  <sequence>
3373  <element name="item" type="xsd:string" minOccurs="1" maxOccurs="100"/>
3374  </sequence>
3375  </complexType>
3376  <complexType name="record">
3377  <sequence>
3378  <element name="names" type="ns:ArrayOfstring" minOccurs="1" maxOccurs="1"/>
3379  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3380  </sequence>
3381  </complexType>
3382 ~~~
3383 </div>
3384 
3385 To change the <i>`item`</i> element name in the WSDL, XML schema, and XML messages, use `__ptrName` where `Name` is the name you want to use.
3386 
3387 @note When <b>`soapcpp2 -e`</b> option <b>`-e`</b> is used, the <i>`ArrayOfstring`</i> becomes a SOAP-encoded array for SOAP 1.1/1.2 RPC encoded messaging:
3388 <div class="alt">
3389 ~~~{.xml}
3390  <import namespace="http://schemas.xmlsoap.org/soap/encoding/"/>
3391  <complexType name="ArrayOfstring">
3392  <complexContent>
3393  <restriction base="SOAP-ENC:Array">
3394  <sequence>
3395  <element name="item" type="xsd:string" minOccurs="1" maxOccurs="100"/>
3396  </sequence>
3397  <attribute ref="SOAP-ENC:arrayType" WSDL:arrayType="xsd:string[]"/>
3398  </restriction>
3399  </complexContent>
3400  </complexType>
3401  <complexType name="record">
3402  <sequence>
3403  <element name="names" type="ns:ArrayOfstring" minOccurs="1" maxOccurs="1"/>
3404  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3405  </sequence>
3406  </complexType>
3407 ~~~
3408 </div>
3409 
3410 Fixed-size arrays can be used to store a fixed number of values:
3411 
3412 ~~~{.cpp}
3413  struct ns__record
3414  {
3415  char* names[10]; // array of 10 char* names
3416  uint64_t SSN;
3417  };
3418 ~~~
3419 
3420 The fixed-size array is similar to a SOAP-encoded array, which can be used with or without SOAP applications. This struct maps to a complexType that references a <i>`Array10Ofstring`</i> complexType with ten <i>`item`</i> elements:
3421 
3422 <div class="alt">
3423 ~~~{.xml}
3424  <complexType name="record">
3425  <sequence>
3426  <element name="names" type="ns:Array10Ofstring" minOccurs="1" maxOccurs="1"/>
3427  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3428  </sequence>
3429  </complexType>
3430  <complexType name="Array10Ofstring">
3431  <sequence>
3432  <element name="item" type="xsd:string" minOccurs="0" maxOccurs="10"/>
3433  </sequence>
3434  </complexType>
3435 ~~~
3436 </div>
3437 
3438 @note When <b>`soapcpp2 -e`</b> option <b>`-e`</b> is used, the <i>`Array10Ofstring`</i> becomes a SOAP-encoded array for SOAP 1.1/1.2 RPC encoded messaging, see previous note.
3439 
3440 🔝 [Back to table of contents](#)
3441 
3442 ### Sequencing with hidden members {#toxsd9-10}
3443 
3444 A member becomes a hidden XML element, i.e. not visibly rendered in XML, when
3445 its name starts with a double underscore. This makes it possible to sequence a
3446 collection of data members, basically by forming a sequence of elements that
3447 can be optional or repeated together.
3448 
3449 To create a sequence of members that are optional, use a pointer-based hidden
3450 member that is a struct with the collection of members to sequence:
3451 
3452 ~~~{.cpp}
3453  struct ns__record
3454  {
3455  std::string name; // required name
3456  struct __ns__optional
3457  {
3458  uint64_t SSN; // SSN in optional group
3459  std::string phone; // phone number in optional group
3460  } *__optional; // optional group
3461  };
3462 ~~~
3463 
3464 Here we used a hidden struct type `__ns__optional` which starts with a double
3465 underscore, because we do not want to define a new global type for the XML
3466 schema we generate. We just need a unique name for a structure that sequences
3467 the two members.
3468 
3469 This struct maps to a complexType in the soapcpp2-generated XML schema:
3470 
3471 <div class="alt">
3472 ~~~{.xml}
3473  <complexType name="record">
3474  <sequence>
3475  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="1"/>
3476  <sequence minOccurs="0" maxOccurs="1">
3477  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3478  <element name="phone" type="xsd:string" minOccurs="1" maxOccurs="1"/>
3479  </sequence>
3480  </sequence>
3481  </complexType>
3482 ~~~
3483 </div>
3484 
3485 The `name` member is a required element of the <i>`ns:record`</i> complexType.
3486 The <i>`ns:record`</i> complexType has an optional sequence of `SSN` and
3487 `phone` elements.
3488 
3489 To create repetitions of a sequence of members, use an array as follows:
3490 
3491 ~~~{.cpp}
3492  struct ns__record
3493  {
3494  std::string name; // required name
3495  $ int sizeofarray; // size of group array
3496  struct __ns__array
3497  {
3498  uint64_t SSN; // SSN in group
3499  std::string phone; // phone number in group
3500  } *__array; // group array
3501  };
3502 ~~~
3503 
3504 This struct maps to a complexType in the soapcpp2-generated XML schema:
3505 
3506 <div class="alt">
3507 ~~~{.xml}
3508  <complexType name="record">
3509  <sequence>
3510  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="1"/>
3511  <sequence minOccurs="0" maxOccurs="unbounded">
3512  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3513  <element name="phone" type="xsd:string" minOccurs="1" maxOccurs="1"/>
3514  </sequence>
3515  </sequence>
3516  </complexType>
3517 ~~~
3518 </div>
3519 
3520 The `name` member is a required element of the <i>`ns:record`</i> complexType.
3521 The <i>`ns:record`</i> complexType has a potentially unbounded sequence of
3522 `SSN` and `phone` elements. You can specify array bounds instead of zero to
3523 unbounded, see [container and array members and their occurrence constraints](#toxsd9-9).
3524 
3525 The XML value space consists of a sequence of SSN and phone elements:
3526 
3527 <div class="alt">
3528 ~~~{.xml}
3529  <ns:record>
3530  <name>numbers</name>
3531  <SSN>1234567890</SSN>
3532  <phone>555-123-4567</phone>
3533  <SSN>1987654320</SSN>
3534  <phone>555-789-1234</phone>
3535  <SSN>2345678901</SSN>
3536  <phone>555-987-6543</phone>
3537  </ns:record>
3538 ~~~
3539 </div>
3540 
3541 🔝 [Back to table of contents](#)
3542 
3543 ### Tagged union members {#toxsd9-11}
3544 
3545 A union member in a class or in a struct cannot be serialized unless a
3546 discriminating *variant selector* member is provided that tells the serializer
3547 which union field to serialize. This effectively creates a *tagged union*.
3548 
3549 The variant selector is associated with the union as a selector-union pair of members.
3550 The variant selector is a member with the name `__union` or `__unionX`, where
3551 `X` can be any name, or by an `$int` member to identify the member as a variant
3552 selector tag:
3553 
3554 ~~~{.cpp}
3555  class ns__record
3556  {
3557  public:
3558  $ int xORnORs; // variant selector with values SOAP_UNION_fieldname
3559  union ns__choice
3560  {
3561  float x;
3562  int n;
3563  char *s;
3564  } u;
3565  std::string name;
3566  };
3567 ~~~
3568 
3569 The variant selector values are auto-generated based on the union name `choice`
3570 and the names of its members `x`, `n`, and `s`:
3571 
3572 - `xORnORs = SOAP_UNION_ns__choice_x` when `u.x` is valid.
3573 
3574 - `xORnORs = SOAP_UNION_ns__choice_n` when `u.n` is valid.
3575 
3576 - `xORnORs = SOAP_UNION_ns__choice_s` when `u.s` is valid.
3577 
3578 - `xORnORs = 0` when none are valid (should only be used with great care,
3579  because XSD validation may fail when content is required but absent).
3580 
3581 This class maps to a complexType with a sequence and choice in the
3582 soapcpp2-generated XML schema:
3583 
3584 <div class="alt">
3585 ~~~{.xml}
3586  <complexType name="record">
3587  <sequence>
3588  <choice>
3589  <element name="x" type="xsd:float" minOccurs="1" maxOccurs="1"/>
3590  <element name="n" type="xsd:int" minOccurs="1" maxOccurs="1"/>
3591  <element name="s" type="xsd:string" minOccurs="0" maxOccurs="1" nillable="true"/>
3592  </choice>
3593  <element name="names" type="xsd:string" minOccurs="1" maxOccurs="1" nillable="true"/>
3594  </sequence>
3595  </complexType>
3596 ~~~
3597 </div>
3598 
3599 An STL container or dynamic array of a union requires wrapping the variant
3600 selector and union member in a struct:
3601 
3602 ~~~{.cpp}
3603  class ns__record
3604  {
3605  public:
3606  std::vector<
3607  struct ns__data // data with a choice of x, n, or s
3608  {
3609  $ int xORnORs; // variant selector with values SOAP_UNION_fieldname
3610  union ns__choice
3611  {
3612  float x;
3613  int n;
3614  char *s;
3615  } u;
3616  }> data; // vector with data
3617  };
3618 ~~~
3619 
3620 and an equivalent definition with a dynamic array instead of a `std::vector`
3621 (you can use this in C with structs):
3622 
3623 ~~~{.cpp}
3624  class ns__record
3625  {
3626  public:
3627  $ int sizeOfdata; // size of dynamic array
3628  struct ns__data // data with a choice of x, n, or s
3629  {
3630  $ int xORnORs; // variant selector with values SOAP_UNION_fieldname
3631  union ns__choice
3632  {
3633  float x;
3634  int n;
3635  char *s;
3636  } u;
3637  } *data; // points to the data array of length sizeOfdata
3638  };
3639 ~~~
3640 
3641 This maps to two complexTypes in the soapcpp2-generated XML schema:
3642 
3643 <div class="alt">
3644 ~~~{.xml}
3645  <complexType name="data">
3646  <choice>
3647  <element name="x" type="xsd:float" minOccurs="1" maxOccurs="1"/>
3648  <element name="n" type="xsd:int" minOccurs="1" maxOccurs="1"/>
3649  <element name="s" type="xsd:string" minOccurs="0" maxOccurs="1" nillable="true"/>
3650  </choice>
3651  </complexType>
3652  <complexType name="record">
3653  <sequence>
3654  <element name="data" type="ns:data" minOccurs="0" maxOccurs="unbounded"/>
3655  </sequence>
3656  </complexType>
3657 ~~~
3658 </div>
3659 
3660 The XML value space consists of a sequence of item elements each wrapped in an
3661 data element:
3662 
3663 <div class="alt">
3664 ~~~{.xml}
3665  <ns:record xmlns:ns="urn:types" ...>
3666  <data>
3667  <n>123</n>
3668  </data>
3669  <data>
3670  <x>3.1</x>
3671  </data>
3672  <data>
3673  <s>hello</s>
3674  </data>
3675  <data>
3676  <s>world</s>
3677  </data>
3678  </ns:record>
3679 ~~~
3680 </div>
3681 
3682 To remove the wrapping data element, simply rename the wrapping struct to
3683 `__ns__data` and the member to `__data` to make this member invisible to the
3684 serializer. The double underscore prefix naming convention is used for the
3685 struct name and member name. Also use a dynamic array instead of a STL
3686 container (so you can also use this approach in C with structs):
3687 
3688 ~~~{.cpp}
3689  class ns__record
3690  {
3691  public:
3692  $ int sizeOfdata; // size of dynamic array
3693  struct __ns__data // contains choice of x, n, or s
3694  {
3695  $ int xORnORs; // variant selector with values SOAP_UNION_fieldname
3696  union ns__choice
3697  {
3698  float x;
3699  int n;
3700  char *s;
3701  } u;
3702  } *__data; // points to the data array of length sizeOfdata
3703  };
3704 ~~~
3705 
3706 This maps to a complexType in the soapcpp2-generated XML schema:
3707 
3708 <div class="alt">
3709 ~~~{.xml}
3710  <complexType name="record">
3711  <sequence minOccurs="0" maxOccurs="unbounded">
3712  <choice>
3713  <element name="x" type="xsd:float" minOccurs="1" maxOccurs="1"/>
3714  <element name="n" type="xsd:int" minOccurs="1" maxOccurs="1"/>
3715  <element name="s" type="xsd:string" minOccurs="0" maxOccurs="1" nillable="true"/>
3716  </choice>
3717  </sequence>
3718  </complexType>
3719 ~~~
3720 </div>
3721 
3722 The XML value space consists of a sequence of <i>`<x>`</i>, <i>`<n>`</i>, and/or <i>`<s>`</i>
3723 elements:
3724 
3725 <div class="alt">
3726 ~~~{.xml}
3727  <ns:record xmlns:ns="urn:types" ...>
3728  <n>123</n>
3729  <x>3.1</x>
3730  <s>hello</s>
3731  <s>world</s>
3732  </ns:record>
3733 ~~~
3734 </div>
3735 
3736 Please note that structs, classes, and unions are unnested by soapcpp2 (as in
3737 the C standard of nested structs and unions). Therefore, the `ns__choice`
3738 union in the `ns__record` class is redeclared at the top level despite its
3739 nesting within the `ns__record` class. This means that you will have to choose
3740 a unique name for each nested struct, class, and union.
3741 
3742 🔝 [Back to table of contents](#)
3743 
3744 ### Tagged void pointer members {#toxsd9-12}
3745 
3746 To serialize data pointed to by `void*` requires run-time type information that
3747 tells the serializer what type of data to serialize by means of a *tagged void
3748 pointer*. This type information is stored in a special type tag member of a
3749 struct/class with the name `__type` or `__typeX`, where `X` can be any name, or
3750 alternatively by an `$int` special member of any name as a type tag:
3751 
3752 ~~~{.cpp}
3753  class ns__record
3754  {
3755  public:
3756  $ int typeOfdata; // type tag with values SOAP_TYPE_T
3757  void *data; // points to some data of type T
3758  };
3759 ~~~
3760 
3761 A type tag member has nonzero values `SOAP_TYPE_T` where `T` is the name of a
3762 struct/class or the name of a primitive type, such as `int`, `std__string` (for
3763 `std::string`), `string` (for `char*`).
3764 
3765 This class maps to a complexType with a sequence in the soapcpp2-generated
3766 XML schema:
3767 
3768 <div class="alt">
3769 ~~~{.xml}
3770  <complexType name="record">
3771  <sequence>
3772  <element name="data" type="xsd:anyType" minOccurs="0" maxOccurs="1"/>
3773  </sequence>
3774  </complexType>
3775 ~~~
3776 </div>
3777 
3778 The XML value space consists of the XML value space of the type with the
3779 addition of an <i>`xsi:type`</i> attribute to the enveloping element:
3780 
3781 <div class="alt">
3782 ~~~{.xml}
3783  <ns:record xmlns:ns="urn:types" ...>
3784  <data xsi:type="xsd:int">123</data>
3785  </ns:record>
3786 ~~~
3787 </div>
3788 
3789 This <i>`xsi:type`</i> attribute is important for the receiving end to distinguish
3790 the type of data to instantiate. The receiver cannot deserialize the data
3791 without an <i>`xsd:type`</i> attribute.
3792 
3793 You can find the `SOAP_TYPE_T` name of each serializable type in the
3794 auto-generated <i>`soapStub.h`</i> file.
3795 
3796 Also all serializable C++ classes have a virtual `int T::soap_type()` member
3797 that returns their `SOAP_TYPE_T` value that you can use.
3798 
3799 When the `void*` pointer is NULL or when `typeOfdata` is zero, the data is not
3800 serialized.
3801 
3802 An STL container or dynamic array of `void*` pointers to <i>`xsd:anyType`</i> data
3803 requires wrapping the type tag and `void*` members in a struct:
3804 
3805 ~~~{.cpp}
3806  class ns__record
3807  {
3808  public:
3809  std::vector<
3810  struct ns__data // data with an xsd:anyType item
3811  {
3812  $ int typeOfitem; // type tag with values SOAP_TYPE_T
3813  void *item; // points to some item of type T
3814  }> data; // vector with data
3815  };
3816 ~~~
3817 
3818 and an equivalent definition with a dynamic array instead of a `std::vector`
3819 (you can use this in C with structs):
3820 
3821 ~~~{.cpp}
3822  class ns__record
3823  {
3824  public:
3825  $ int sizeOfdata; // size of dynamic array
3826  struct ns__data // data with an xsd:anyType item
3827  {
3828  $ int typeOfitem; // type tag with values SOAP_TYPE_T
3829  void *item; // points to some item of type T
3830  } *data; // points to the data array of length sizeOfdata
3831  };
3832 ~~~
3833 
3834 This maps to two complexTypes in the soapcpp2-generated XML schema:
3835 
3836 <div class="alt">
3837 ~~~{.xml}
3838  <complexType name="data">
3839  <sequence>
3840  <element name="item" type="xsd:anyType" minOccurs="1" maxOccurs="1" nillable="true"/>
3841  </sequence>
3842  </complexType>
3843  <complexType name="record">
3844  <sequence>
3845  <element name="data" type="ns:data" minOccurs="0" maxOccurs="unbounded"/>
3846  </sequence>
3847  </complexType>
3848 ~~~
3849 </div>
3850 
3851 The XML value space consists of a sequence of item elements each wrapped in a
3852 data element:
3853 
3854 <div class="alt">
3855 ~~~{.xml}
3856  <ns:record xmlns:ns="urn:types" ...>
3857  <data>
3858  <item xsi:type="xsd:int">123</item>
3859  </data>
3860  <data>
3861  <item xsi:type="xsd:double">3.1</item>
3862  </data>
3863  <data>
3864  <item xsi:type="xsd:string">abc</item>
3865  </data>
3866  </ns:record>
3867 ~~~
3868 </div>
3869 
3870 To remove the wrapping data elements, simply rename the wrapping struct and
3871 member to `__data` to make this member invisible to the serializer with the
3872 double underscore prefix naming convention. Also use a dynamic array instead
3873 of a STL container (you can use this in C with structs):
3874 
3875 ~~~{.cpp}
3876  class ns__record
3877  {
3878  public:
3879  $ int sizeOfdata; // size of dynamic array
3880  struct __data // contains xsd:anyType item
3881  {
3882  $ int typeOfitem; // type tag with values SOAP_TYPE_T
3883  void *item; // points to some item of type T
3884  } *__data; // points to the data array of length sizeOfdata
3885  };
3886 ~~~
3887 
3888 This maps to a complexType in the soapcpp2-generated XML schema:
3889 
3890 <div class="alt">
3891 ~~~{.xml}
3892  <complexType name="record">
3893  <sequence minOccurs="0" maxOccurs="unbounded">
3894  <element name="item" type="xsd:anyType" minOccurs="1" maxOccurs="1"/>
3895  </sequence>
3896  </complexType>
3897 ~~~
3898 </div>
3899 
3900 The XML value space consists of a sequence of data elements:
3901 
3902 <div class="alt">
3903 ~~~{.xml}
3904  <ns:record xmlns:ns="urn:types" ...>
3905  <item xsi:type="xsd:int">123</item>
3906  <item xsi:type="xsd:double">3.1</item>
3907  <item xsi:type="xsd:string">abc</item>
3908  </ns:record>
3909 ~~~
3910 </div>
3911 
3912 Again, please note that structs, classes, and unions are unnested by soapcpp2
3913 (as in the C standard of nested structs and unions). Therefore, the `__data`
3914 struct in the `ns__record` class is redeclared at the top level despite its
3915 nesting within the `ns__record` class. This means that you will have to choose
3916 a unique name for each nested struct, class, and union.
3917 
3918 @see Section [XSD type bindings](#typemap2).
3919 
3920 🔝 [Back to table of contents](#)
3921 
3922 ### Adding get and set methods {#toxsd9-13}
3923 
3924 A public `get` method may be added to a class or struct, which will be
3925 triggered by the deserializer. This method will be invoked right after the
3926 instance is populated by the deserializer. The `get` method can be used to
3927 update or verify deserialized content. It should return `SOAP_OK` or set
3928 `soap::error` to a nonzero error code and return it.
3929 
3930 A public `set` method may be added to a class or struct, which will be
3931 triggered by the serializer. The method will be invoked just before the
3932 instance is serialized. Likewise, the `set` method should return `SOAP_OK` or
3933 set set `soap::error` to a nonzero error code and return it.
3934 
3935 For example, adding a `set` and `get` method to a class declaration:
3936 
3937 ~~~{.cpp}
3938  class ns__record
3939  {
3940  public:
3941  int set(struct soap*); // triggered before serialization
3942  int get(struct soap*); // triggered after deserialization
3943  ...
3944  };
3945 ~~~
3946 
3947 To add these and othe rmethods to classes and structs with wsdl2h and
3948 <i>`typemap.dat`</i>, please see [class/struct member additions](#typemap3).
3949 
3950 🔝 [Back to table of contents](#)
3951 
3952 ### Operations on classes and structs {#toxsd9-14}
3953 
3954 The following functions/macros are generated by soapcpp2 for each type `T`,
3955 which should make it easier to send, receive, and copy XML data in C and in
3956 C++:
3957 
3958 - `int soap_write_T(struct soap*, T*)` writes an instance of `T` to a file via
3959  file descriptor `int soap::sendfd)` or to a stream via `std::ostream
3960  *soap::os` (C++ only) or saves into a NUL-terminated string by setting
3961  `const char **soap::os` to a string pointer to be set (C only). Returns
3962  `SOAP_OK` on success or an error code, also stored in `soap::error`.
3963 
3964 - `int soap_read_T(struct soap*, T*)` reads an instance of `T` from a file via
3965  file descriptor `int soap::recvfd)` or from a stream via `std::istream
3966  *soap::is` (C++ only) or reads from a NUL-termianted string `const char
3967  *soap::is` (C only). Returns `SOAP_OK` on success or an error code, also
3968  stored in `soap::error`.
3969 
3970 - `void soap_default_T(struct soap*, T*)` sets an instance `T` to its default
3971  value, resetting members of a struct to their initial values (for classes we
3972  use method `T::soap_default`, see below). If `T` is a struct that has a
3973  `soap` pointer member to a `::soap` context then this pointer member will be
3974  set to the first argument passed to this function to initialize its `soap`
3975  pointer member.
3976 
3977 - `T * soap_dup_T(struct soap*, T *dst, const T *src)` (requires <b>`soapcpp2 -Ec`</b>)
3978  deep copy `src` into `dst`, replicating all deep cycles and shared pointers
3979  when a managing `soap` context is provided as argument. When `dst` is NULL,
3980  allocates space for `dst` and returns a pointer to the allocated copy. Deep
3981  copy results in a tree when the `soap` context is NULL, but the presence of
3982  deep cycles will lead to non-termination. Use flag `SOAP_XML_TREE` with
3983  managing context to copy into a tree without cycles and pointers to shared
3984  objects. Returns `dst` or allocated copy when `dst` is NULL.
3985 
3986 - `void soap_del_T(const T*)` (requires <b>`soapcpp2 -Ed`</b>) deletes all
3987  heap-allocated members of this object by deep deletion ONLY IF this object
3988  and all of its (deep) members are not managed by a `soap` context AND the deep
3989  structure is a tree (no cycles and co-referenced objects by way of multiple
3990  (non-smart) pointers pointing to the same data). Can be safely used after
3991  `T * soap_dup_T(NULL, NULL, const T*)` to delete the deep copy returned.
3992  Does not delete the object itself.
3993 
3994 When in C++ mode, soapcpp2 tool adds several methods to classes in addition to
3995 adding a default constructor and destructor (when these were not explicitly
3996 declared).
3997 
3998 The public methods added to a class `T`:
3999 
4000 - `virtual int T::soap_type(void)` returns a unique type ID (`SOAP_TYPE_T`).
4001  This numeric ID can be used to distinguish base from derived instances.
4002 
4003 - `virtual void T::soap_default(struct soap*)` sets all data members to
4004  default values. If class `T` has a `soap` pointer member to a `::soap`
4005  context then this pointer member will be set to the argument passed to this
4006  function to initialize its `soap` pointer member.
4007 
4008 - `virtual void T::soap_serialize(struct soap*) const` serializes object to
4009  prepare for SOAP 1.1/1.2 encoded output (or with `SOAP_XML_GRAPH`) by
4010  analyzing its (cyclic) structures.
4011 
4012 - `virtual int T::soap_put(struct soap*, const char *tag, const char *type) const`
4013  emits object in XML, compliant with SOAP 1.1 encoding style, return error
4014  code or `SOAP_OK`. Requires `soap_begin_send(soap)` and
4015  `soap_end_send(soap)`.
4016 
4017 - `virtual int T::soap_out(struct soap*, const char *tag, int id, const char *type) const`
4018  emits object in XML, with tag and optional id attribute and <i>`xsi:type`</i>,
4019  return error code or `SOAP_OK`. Requires `soap_begin_send(soap)` and
4020  `soap_end_send(soap)`.
4021 
4022 - `virtual void * T::soap_get(struct soap*, const char *tag, const char *type)`
4023  Get object from XML, compliant with SOAP 1.1 encoding style, return pointer
4024  to object or NULL on error. Requires `soap_begin_recv(soap)` and
4025  `soap_end_recv(soap)`.
4026 
4027 - `virtual void *soap_in(struct soap*, const char *tag, const char *type)`
4028  Get object from XML, with matching tag and type (NULL matches any tag and
4029  type), return pointer to object or NULL on error. Requires
4030  `soap_begin_recv(soap)` and `soap_end_recv(soap)`
4031 
4032 - `virtual T * T::soap_alloc(void) const` returns a new object of type `T`,
4033  default initialized and not managed by a `soap` context.
4034 
4035 - `virtual T * T::soap_dup(struct soap*) const` (requires <b>`soapcpp2 -Ec`</b>)
4036  returns a duplicate of this object by deep copying, replicating all deep
4037  cycles and shared pointers when a managing `soap` context is provided as
4038  argument. Deep copy is a tree when argument is NULL, but the presence of
4039  deep cycles will lead to non-termination. Use flag `SOAP_XML_TREE` with the
4040  managing context to copy into a tree without cycles and pointers to shared
4041  objects.
4042 
4043 - `virtual void T::soap_del() const` (rquires <b>`soapcpp2 -Ed`</b>) deletes all
4044  heap-allocated members of this object by deep deletion ONLY IF this object
4045  and all of its (deep) members are not managed by a `soap` context AND the deep
4046  structure is a tree (no cycles and co-referenced objects by way of multiple
4047  (non-smart) pointers pointing to the same data). Can be safely used after
4048  `soap_dup(NULL)` to delete the deep copy. Does not delete the object itself.
4049 
4050 Also, there are four variations of `soap_new_T` for
4051 class/struct/template type `T` that soapcpp2 auto-generates to create instances
4052 on a context-managed heap:
4053 
4054 - `T * soap_new_T(struct soap*)` returns a new instance of `T` with default data
4055  member initializations that are set with the soapcpp2 auto-generated `void
4056  T::soap_default(struct soap*)` method), but ONLY IF the soapcpp2
4057  auto-generated default constructor is used that invokes `soap_default()` and
4058  was not replaced by a user-defined default constructor.
4059 
4060 - `T * soap_new_T(struct soap*, int n)` returns an array of `n` new instances of
4061  `T`. Similar to the above, instances are initialized.
4062 
4063 - `T * soap_new_req_T(struct soap*, ...)` returns a new instance of `T` and sets
4064  the required data members to the values specified in `...`. The required data
4065  members are those with nonzero minOccurs, see the subsections on
4066  [(smart) pointer members and their occurrence constraints](#toxsd9-8) and
4067  [container and array members and their occurrence constraints](#toxsd9-9).
4068 
4069 - `T * soap_new_set_T(struct soap*, ...)` returns a new instance of `T` and sets
4070  the public/serializable data members to the values specified in `...`.
4071 
4072 The above functions can be invoked with a NULL `soap` context, but we will be
4073 responsible to use `delete T` to remove this instance from the unmanaged heap.
4074 
4075 The allocation functions return NULL when memory allocation failed.
4076 
4077 🔝 [Back to table of contents](#)
4078 
4079 Special classes and structs {#toxsd10}
4080 ---------------------------
4081 
4082 The following applies to both structs and classes. The examples show classes
4083 in C++. For C, use structs and omit the C++ features. Structs also require
4084 the use of the `struct` keyword, otherwise soapcpp2 will throw a syntax error.
4085 
4086 ### SOAP-encoded arrays {#toxsd10-1}
4087 
4088 A class or struct with the following layout is a one-dimensional SOAP-encoded
4089 array type:
4090 
4091 ~~~{.cpp}
4092  class ArrayOfT
4093  {
4094  public:
4095  T *__ptr; // array pointer
4096  int __size; // array size
4097  };
4098 ~~~
4099 
4100 where `T` is the array element type. A multidimensional SOAP Array is:
4101 
4102 ~~~{.cpp}
4103  class ArrayOfT
4104  {
4105  public:
4106  T *__ptr; // array pointer
4107  int __size[N]; // array size of each dimension
4108  };
4109 ~~~
4110 
4111 where `N` is the constant number of dimensions. The pointer points to an array
4112 of `__size[0]*__size[1]* ... * __size[N-1]` elements.
4113 
4114 This maps to a complexType restriction of SOAP-ENC:Array in the
4115 soapcpp2-generated XML schema:
4116 
4117 <div class="alt">
4118 ~~~{.xml}
4119  <complexType name="ArrayOfT">
4120  <complexContent>
4121  <restriction base="SOAP-ENC:Array">
4122  <sequence>
4123  <element name="item" type="T" minOccurs="0" maxOccurs="unbounded" nillable="true"/>
4124  </sequence>
4125  <attribute ref="SOAP-ENC:arrayType" WSDL:arrayType="ArrayOfT[]"/>
4126  </restriction>
4127  </complexContent>
4128  </complexType>
4129 ~~~
4130 </div>
4131 
4132 The name of the class can be arbitrary. We often use `ArrayOfT` without a
4133 prefix to distinguish arrays from other classes and structs.
4134 
4135 With SOAP 1.1 encoding, an optional offset member can be added that controls
4136 the start of the index range for each dimension:
4137 
4138 ~~~{.cpp}
4139  class ArrayOfT
4140  {
4141  public:
4142  T *__ptr; // array pointer
4143  int __size[N]; // array size of each dimension
4144  int __offset[N]; // array offsets to start each dimension
4145  };
4146 ~~~
4147 
4148 For example, we can define a matrix of floats as follows:
4149 
4150 ~~~{.cpp}
4151  class Matrix
4152  {
4153  public:
4154  double *__ptr;
4155  int __size[2];
4156  };
4157 ~~~
4158 
4159 The following code populates the matrix and serializes it in XML:
4160 
4161 ~~~{.cpp}
4162  soap *soap = soap_new1(SOAP_XML_INDENT);
4163  Matrix A;
4164  double a[6] = { 1, 2, 3, 4, 5, 6 };
4165  A.__ptr = a;
4166  A.__size[0] = 2;
4167  A.__size[1] = 3;
4168  soap_write_Matrix(soap, &A);
4169 ~~~
4170 
4171 Matrix A is serialized as an array with 2x3 values:
4172 
4173 <div class="alt">
4174 ~~~{.xml}
4175  <SOAP-ENC:Array SOAP-ENC:arrayType="xsd:double[2,3]" ...>
4176  <item>1</item>
4177  <item>2</item>
4178  <item>3</item>
4179  <item>4</item>
4180  <item>5</item>
4181  <item>6</item>
4182  </SOAP-ENC:Array>
4183 ~~~
4184 </div>
4185 
4186 🔝 [Back to table of contents](#)
4187 
4188 ### XSD hexBinary and base64Binary types {#toxsd10-2}
4189 
4190 A special case of a one-dimensional array is used to define <i>`xsd:hexBinary`</i> and
4191 <i>`xsd:base64Binary`</i> types when the pointer type is `unsigned char`:
4192 
4193 ~~~{.cpp}
4194  class xsd__hexBinary
4195  {
4196  public:
4197  unsigned char *__ptr; // points to raw binary data
4198  int __size; // size of data
4199  };
4200 ~~~
4201 
4202 and
4203 
4204 ~~~{.cpp}
4205  class xsd__base64Binary
4206  {
4207  public:
4208  unsigned char *__ptr; // points to raw binary data
4209  int __size; // size of data
4210  };
4211 ~~~
4212 
4213 To create a new binary type, use either one of the following three forms that
4214 declare a new `ns__binary` type that is a <i>`simpleType`</i> restriction of
4215 <i>`xsd:base64Binary`</i>:
4216 
4217 ~~~{.cpp}
4218  typedef xsd__base64Binary ns__binary;
4219 ~~~
4220 ~~~{.cpp}
4221  class ns__binary : public xsd__base64Binary
4222  {
4223  ... // attribute members (@) and class methods
4224  };
4225 ~~~
4226 ~~~{.cpp}
4227  class ns__binary
4228  {
4229  public:
4230  unsigned char *__ptr; // points to raw binary data
4231  int __size; // size of data
4232  ... // attribute members (@) and class methods (optional)
4233  };
4234 ~~~
4235 
4236 Here, `xsd__base64Binary` is reused in the first two cases, where
4237 `xsd__base64Binary` is declared as shown above.
4238 
4239 @see [DIME/MIME/MTOM attachment binary types](#toxsd10-3)
4240 
4241 🔝 [Back to table of contents](#)
4242 
4243 ### DIME/MIME/MTOM attachment binary types {#toxsd10-3}
4244 
4245 A class or struct with a binary content layout can be extended to support
4246 attachments. The following struct or class type can be used as DIME, MIME, and
4247 MTOM attachment and also be used for <i>`xsd:base64Binary`</i> type values:
4248 
4249 ~~~{.cpp}
4250  class xsd__base64Binary
4251  {
4252  public:
4253  unsigned char *__ptr; // points to raw binary data
4254  int __size; // size of data
4255  char *id; // NULL to generate an id, or set to a unique UUID
4256  char *type; // MIME type of the data
4257  char *options; // optional description of MIME attachment
4258  };
4259 ~~~
4260 
4261 When the `id`, `type`, or `options` members are non-NULL, an attachment will be
4262 used instead of base64 XML content. DIME attachments are the default. To
4263 switch to MIME use the `SOAP_ENC_MIME` context flag. To switch to MTOM use the
4264 `SOAP_ENC_MTOM` context flag.
4265 
4266 MTOM is typically used with XOP <i>`<xop:Include>`</i> elements, which is
4267 preferred and declared as follows:
4268 
4269 ~~~{.cpp}
4270  //gsoap xop schema import: http://www.w3.org/2004/08/xop/include
4271  class _xop__Include
4272  {
4273  public:
4274  unsigned char *__ptr; // points to raw binary data
4275  int __size; // size of data
4276  char *id; // NULL to generate an id, or set to a unique UUID
4277  char *type; // MIME type of the data
4278  char *options; // optional description of MIME attachment
4279  };
4280 ~~~
4281 
4282 Attachments are beyond the scope of this article. See the
4283 [gSOAP user guide.](../../guide/html/index.html) for more details.
4284 
4285 🔝 [Back to table of contents](#)
4286 
4287 ### Wrapper class/struct with simpleContent {#toxsd10-4}
4288 
4289 A class or struct with the following layout is a complexType that wraps
4290 simpleContent:
4291 
4292 ~~~{.cpp}
4293  class ns__simple
4294  {
4295  public:
4296  T __item; // primitive type for the simpleContent
4297  ... // attribute members (@) and class methods (optional)
4298  };
4299 ~~~
4300 
4301 The type `T` is a primitive type (`bool`, `enum`, `time_t`, numeric and string
4302 types), `xsd__hexBinary`, `xsd__base64Binary`, and custom serializers, such as
4303 `xsd__dateTime`.
4304 
4305 This maps to a complexType with simpleContent in the soapcpp2-generated XML
4306 schema:
4307 
4308 <div class="alt">
4309 ~~~{.xml}
4310  <complexType name="simple">
4311  <simpleContent>
4312  <extension base="T"/>
4313  </simpleContent>
4314  </complexType>
4315 ~~~
4316 </div>
4317 
4318 A wrapper class/struct may include any number of members that are declared as
4319 attributes with `@`, which should be placed after the `__item` member.
4320 
4321 🔝 [Back to table of contents](#)
4322 
4323 ### DOM anyType and anyAttribute {#toxsd10-5}
4324 
4325 Use of a DOM is optional and enabled by `#import "dom.h"` to use the DOM
4326 `xsd__anyType` element node and `xsd__anyAttribute` attribute node:
4327 
4328 ~~~{.cpp}
4329  #import "dom.h"
4330 
4331  class ns__record
4332  {
4333  public:
4334  @ xsd__anyAttribute attributes; // optional DOM attributes
4335  xsd__anyType *name; // optional DOM element (pointer means minOccurs=0)
4336  xsd__anyType address; // required DOM element (minOccurs=1)
4337  xsd__anyType email 0; // optional DOM element (minOccurs=0)
4338  ... // other members
4339  };
4340 ~~~
4341 
4342 where `name` contains XML stored in a DOM node set and `attributes` is a list
4343 of all visibly rendered attributes. The name `attributes` is arbitrary and any
4344 name will suffice.
4345 
4346 You should place the `xsd__anyType` members at the end of the struct or class.
4347 This ensures that the DOM members are populated last as a "catch all". A
4348 member name starting with double underscore is a wildcard member. These
4349 members are placed at the end of a struct or class automatically by soapcpp2.
4350 
4351 An `#import "dom.h"` import is automatically added by <b>`wsdl2h -d`</b> with
4352 option <b>`-d`</b> to bind <i>`xsd:anyType`</i> to DOM nodes, and also to
4353 populate <i>`xsd:any`</i>, <i>`xsd:anyAttribute`</i> and <i>`xsd:mixed`</i> XML
4354 content:
4355 
4356 ~~~{.cpp}
4357  #import "dom.h"
4358 
4359  class ns__record
4360  {
4361  public:
4362  @ xsd__anyAttribute __anyAttribute; // optional DOM attributes
4363  std::vector<xsd__anyType> __any 0; // optional DOM elements (minOccurs=0)
4364  xsd__anyType __mixed 0; // optional mixed content (minOccurs=0)
4365  ... // other members
4366  };
4367 ~~~
4368 
4369 where the members prefixed with `__` are "invisible" to the XML parser, meaning
4370 that these members are not bound to XML tag names.
4371 
4372 In C you can use a dynamic arrary instead of `std::vector`:
4373 
4374 ~~~{.cpp}
4375  #import "dom.h"
4376 
4377  struct ns__record
4378  {
4379  @ xsd__anyAttribute __anyAttribute; // optional DOM attributes
4380  $ int __sizeOfany; // size of the array
4381  xsd__anyType *__any; // optional DOM elements (pointer means minOccurs=0)
4382  xsd__anyType __mixed 0; // optional mixed content (minOccurs=0)
4383  ... // other members
4384  };
4385 ~~~
4386 
4387 Classes can inherit DOM, which enables full use of polymorphism with one base
4388 DOM class:
4389 
4390 ~~~{.cpp}
4391  #import "dom.h"
4392 
4393  class ns__record : public xsd__anyType
4394  {
4395  public:
4396  std::vector<xsd__anyType*> array; // array of objects of any class
4397  ... // other members
4398  };
4399 ~~~
4400 
4401 This permits an `xsd__anyType` pointer to refer to a derived class such as
4402 `ns__record`, which will be serialized with an <i>`xsi:type`</i> attribute that is
4403 set to "ns:record". The <i>`xsi:type`</i> attributes add the necessary type information
4404 to distinguish the XML content from the DOM base type. This is important for
4405 the receiving end: without <i>`xsd:type`</i> attributes with type names, only base DOM
4406 objects are recognized and instantiated.
4407 
4408 Because C lacks object-oriented programming concepts such as class inheritance
4409 and polymorphism, you should consider using [derived types in C and C++](#toxsd9-1-1).
4410 
4411 An alternative is to use the special [tagged void pointer members](#toxsd9-12)
4412 to serialize data pointed to by a `void*` member, which can be any serializable
4413 type, such as derived types. This approach uses <i>`xsi:type`</i> attributes
4414 to identify the type of value serialized.
4415 
4416 To ensure that wsdl2h generates pointer-based `xsd__anyType` DOM nodes with
4417 <b>`wsdl2h -d`</b> using option <b>`-d`</b> for <i>`xsd:any`</i>, add the
4418 following line to <i>`typemap.dat`</i>:
4419 
4420  xsd__any = | xsd__anyType*
4421 
4422 This lets wsdl2h produce class/struct members and containers with
4423 `xsd__anyType*` for <i>`xsd:any`</i> instead of `xsd__anyType`. To just force all
4424 <i>`xsd:anyType`</i> uses to be pointer-based, declare in <i>`typemap.dat`</i>:
4425 
4426  xsd__anyType = | xsd__anyType*
4427 
4428 If you use <b>`wsdl2h -d -p`</b> using options <b>`-d`</b> and <b>`-p`</b> then
4429 every class will inherit DOM as shown above. Without option `-d`, an
4430 `xsd__anyType` type is generated to serve as the root type in the type
4431 hierarchy:
4432 
4433 ~~~{.cpp}
4434  class xsd__anyType { _XML __item; struct soap *soap; };
4435 
4436  class ns__record : public xsd__anyType
4437  {
4438  ...
4439  };
4440 ~~~
4441 
4442 where the `_XML __item` member holds any XML content as a literal XML string.
4443 
4444 To use the DOM API, compile <i>`dom.c`</i> (or <i>`dom.cpp`</i> for C++), or
4445 link the gSOAP library with <b>`-lgsoapssl`</b> (or <b>`-lgsoapssl++`</b> for C++).
4446 
4447 @see Documentation of [XML DOM and XPath](http://www.genivia.com/doc/dom/html)
4448 for more details.
4449 
4450 🔝 [Back to table of contents](#)
4451 
4452 Directives {#directives}
4453 ==========
4454 
4455 You can use `//gsoap` directives in the interface header file with the data
4456 binding interface for soapcpp2. These directives are used to configure the
4457 code generated by soapcpp2 by declaring various. properties of Web services
4458 and XML schemas. When using the wsdl2h tool, you will notice that wsdl2h
4459 generates directives automatically based on the WSDL and XSD input.
4460 
4461 Service directives are applicable to service and operations described by WSDL.
4462 Schema directives are applicable to types, elements, and attributes defined by
4463 XML schemas.
4464 
4465 🔝 [Back to table of contents](#)
4466 
4467 Service directives {#directives-1}
4468 ------------------
4469 
4470 A service directive must start at a new line and is of the form:
4471 
4472 ~~~{.cpp}
4473  //gsoap <prefix> service <property>: <value>
4474 ~~~
4475 
4476 where `<prefix>` is the XML namespace prefix of a service binding. The
4477 `<property>` and `<value>` fields are one of the following:
4478 
4479 property | value
4480 --------------- | -----
4481 `name` | name of the service, optionally followed by text describing the service
4482 `namespace` | URI of the WSDL targetNamespace
4483 `documentation` | text describing the service (see also the `name` property), multiple permitted
4484 `doc` | an alias for the `documentation` property
4485 `style` | `document` (default) SOAP messaging style or `rpc` for SOAP RPC
4486 `encoding` | `literal` (default), `encoded` for SOAP encoding, or a custom URI
4487 `protocol` | specifies SOAP or REST, see below
4488 `port` | URL of the service endpoint, usually an http or https address, to use in the WSDL definitions/service/port/address/\@location
4489 `location` | an alias for the `port` property
4490 `endpoint` | an alias for the `port` property
4491 `transport` | URI declaration of the transport, usually `http://schemas.xmlsoap.org/soap/http`
4492 `definitions` | name of the WSDL definitions/\@name
4493 `type` | name of the WSDL definitions/portType/\@name (WSDL2.0 interface/\@name)
4494 `portType` | an alias for the `type` property (`portType` follows SOAP 1.1 naming conventions)
4495 `interface` | an alias for the `type` property (`interface` follows SOAP 1.2 naming conventions)
4496 `binding` | name of the WSDL definitions/binding/\@name
4497 `portName` | name of the WSDL definitions/service/port/\@name
4498 `executable` | name of the "executable" to use in the WSDL definitions/service/port/address/\@location
4499 
4500 The service `name` and `namespace` properties are required in order to generate
4501 a valid WSDL with soapcpp2. The other properties are optional.
4502 
4503 The `style` and `encoding` property defaults are changed with
4504 <b>`soapcpp2 -e`</b> option <b>`-e`</b> to `rpc` and `encoded`, respectively.
4505 
4506 The `protocol` property is `SOAP` by default (SOAP 1.1). Protocol property
4507 values are:
4508 
4509 protocol value | description
4510 -------------- | -----------
4511 `SOAP` | SOAP transport, supporting both SOAP 1.1 and 1.2
4512 `SOAP1.1` | SOAP 1.1 transport (same as `soapcpp2 -1`)
4513 `SOAP1.2` | SOAP 1.2 transport (same as `soapcpp2 -2`)
4514 `SOAP-GET` | one-way SOAP 1.1 or 1.2 with HTTP GET
4515 `SOAP1.1-GET` | one-way SOAP 1.1 with HTTP GET
4516 `SOAP1.2-GET` | one-way SOAP 1.2 with HTTP GET
4517 `HTTP` | non-SOAP REST protocol with HTTP POST
4518 `POST` | non-SOAP REST protocol with HTTP POST
4519 `GET` | non-SOAP REST protocol with HTTP GET
4520 `PUT` | non-SOAP REST protocol with HTTP PUT
4521 `DELETE` | non-SOAP REST protocol with HTTP DELETE
4522 
4523 You can bind service operations to the WSDL namespace of a service by using the
4524 namespace prefix as part of the identifier name of the function that defines
4525 the service operation:
4526 
4527 ~~~{.cpp}
4528  int prefix__func(arg1, arg2, ..., argn, result);
4529 ~~~
4530 
4531 You can override the `port` endpoint URL at runtime in the auto-generated
4532 `soap_call_prefix__func` service call (C/C++ client side) and in the C++ proxy
4533 class service call.
4534 
4535 🔝 [Back to table of contents](#)
4536 
4537 Service method directives {#directives-2}
4538 -------------------------
4539 
4540 Service properties are applicable to a service and to all of its operations.
4541 Service method directives are specifically applicable to a service operation.
4542 
4543 A service method directive is of the form:
4544 
4545 ~~~{.cpp}
4546  //gsoap <prefix> service method-<property>: <method> <value>
4547 ~~~
4548 
4549 where `<prefix>` is the XML namespace prefix of a service binding and
4550 `<method>` is the unqualified name of a service operation. The `<property>`
4551 and `<value>` fields are one of the following:
4552 
4553 method property | value
4554 --------------------------- | -----
4555 `method-documentation` | text describing the service operation
4556 `method` | an alias for the `method-documentation` property
4557 `method-action` | `""` or URI SOAPAction HTTP header, or URL query string for REST protocols
4558 `method-input-action` | `""` or URI SOAPAction HTTP header of service request messages
4559 `method-output-action` | `""` or URI SOAPAction HTTP header of service response messages
4560 `method-fault-action` | `""` or URI SOAPAction HTTP header of service fault messages
4561 `method-header-part` | member name of the `SOAP_ENV__Header` struct used in SOAP Header
4562 `method-input-header-part` | member name of the `SOAP_ENV__Header` struct used in SOAP Headers of requests
4563 `method-output-header-part` | member name of the `SOAP_ENV__Header` struct used in SOAP Headers of responses
4564 `method-fault` | type name of a struct or class member used in `SOAP_ENV__Details` struct
4565 `method-mime-type` | REST content type or SOAP MIME attachment content type(s)
4566 `method-input-mime-type` | REST content type or SOAP MIME attachment content type(s) of request message
4567 `method-output-mime-type` | REST content type or SOAP MIME attachment content type(s) of response message
4568 `method-style` | `document` or `rpc`
4569 `method-encoding` | `literal`, `encoded`, or a custom URI for encodingStyle of messages
4570 `method-response-encoding` | `literal`, `encoded`, or a custom URI for encodingStyle of response messages
4571 `method-protocol` | SOAP or REST, see [service directives](#directives-1)
4572 
4573 The `method-header-part` properties can be repeated for a service operation to
4574 declare multiple SOAP Header parts that the service operation requires. You
4575 can use `method-input-header-part` and `method-output-header-part` to
4576 differentiate between request and response messages.
4577 
4578 The `method-fault` property can be repeated for a service operation to declare
4579 multiple faults that the service operation may return.
4580 
4581 The `method-action` property serves two purposes:
4582 
4583 -# To set the SOAPAction header for SOAP protocols, i.e. sets the
4584  definitions/binding/operation/SOAP:operation/\@soapAction.
4585 
4586 -# To set the URL query string for endpoints with REST protocols, i.e. sets the
4587  definitions/binding/operation/HTTP:operation/\@location, which specifies
4588  a URL query string (starts with a `?`) to complete the service endpoint URL
4589  or extends the endpoint URL with a local path (starts with a `/`).
4590 
4591 Use `method-input-action` and `method-output-action` to differentiate the
4592 SOAPAction between SOAP request and response messages.
4593 
4594 You can always override the port endpoint URL and action values at runtime in
4595 the auto-generated `soap_call_prefix__func` service call (C/C++ client side)
4596 and in the auto-generated C++ proxy class service calls. A runtime NULL
4597 endpoint URL and/or action uses the defaults set by these directives.
4598 
4599 The `method-mime-type` property serves two purposes:
4600 
4601 -# To set the type of MIME/MTOM attachments used with SOAP protocols. Multiple
4602  attachment types can be declared for a SOAP service operation, i.e. adds
4603  definitions/binding/operation/input/MIME:multipartRelated/MIME:part/MIME:content/\@type
4604  for each type specified.
4605 
4606 -# To set the MIME type of a REST operation. This replaces XML declared in
4607  WSDL by definitions/binding/operation/(input|output)/MIME:mimeXml with
4608  MIME:content/\@type. Use `application/x-www-form-urlencoded` with REST POST
4609  and PUT protocols to send encoded form data automatically instead of XML.
4610  Only primitive type values can be transmitted with form data, such as
4611  numbers and strings, i.e. only types that are legal to use as
4612  [attributes members](#toxsd9-5).
4613 
4614 Use `method-input-mime-type` and `method-output-mime-type` to differentiate the
4615 attachment types between request and response messages.
4616 
4617 🔝 [Back to table of contents](#)
4618 
4619 Schema directives {#directives-3}
4620 -----------------
4621 
4622 A schema directive is of the form:
4623 
4624 ~~~{.cpp}
4625  //gsoap <prefix> schema <property>: <value>
4626 ~~~
4627 
4628 where `<prefix>` is the XML namespace prefix of a schema. The `<property>` and
4629 `<value>` fields are one of the following:
4630 
4631 property | value
4632 --------------- | -----
4633 `namespace` | URI of the XSD targetNamespace
4634 `namespace2` | alternate URI pattern for the XSD namespace (i.e. URI is also accepted by the XML parser)
4635 `import` | URI of an imported namespace, as an alternative or in addition to `namespace`, adds `xsd:import` to the generated WSDL and XSD files
4636 `form` | `unqualified` (default) or `qualified` local element and attribute form defaults
4637 `elementForm` | `unqualified` (default) or `qualified` local element form default
4638 `attributeForm` | `unqualified` (default) or `qualified` local attribute form default
4639 `typed` | `no` (default) or `yes` for serializers to add `xsi:type` attributes to XML
4640 
4641 To learn more about the local form defaults, see [qualified and unqualified members.](#toxsd9-6)
4642 
4643 The `namespace2` URI is a pattern with `*` matching any sequence of characters
4644 and `-` matching any character. This pattern instructs the XML parser and validator
4645 to also accept the URI pattern as a valid namespace for the specified `<prefix>`.
4646 
4647 The `typed` property is implicitly `yes` when <b>`soapcpp2 -t`</b> option <b>`-t`</b> is used.
4648 
4649 🔝 [Back to table of contents](#)
4650 
4651 Schema type directives {#directives-4}
4652 ----------------------
4653 
4654 A schema type directive is of the form:
4655 
4656 ~~~{.cpp}
4657  //gsoap <prefix> schema type-<property>: <name> <value>
4658  //gsoap <prefix> schema type-<property>: <name>::<member> <value>
4659 ~~~
4660 
4661 where `<prefix>` is the XML namespace prefix of a schema and `<name>` is an
4662 unqualified name of a C/C++ type, and the optional `<member>` is a class/struct
4663 members or enum constant.
4664 
4665 You can describe a type with one of the following:
4666 
4667 type property | value
4668 -------------------- | -----
4669 `type-documentation` | text describing the schema type
4670 `type` | an alias for the `type-documentation` property
4671 
4672 For example, you can add a description to an enumeration:
4673 
4674 ~~~{.cpp}
4675  //gsoap ns schema type: Vowels The letters A, E, I, O, U, and sometimes Y
4676  //gsoap ns schema type: Vowels::Y A vowel, sometimes
4677  enum class ns__Vowels : char { A = 'A', E = 'E', I = 'I', O = 'O', U = 'U', Y = 'Y' };
4678 ~~~
4679 
4680 This documented enumeration maps to a simpleType restriction of <i>`xsd:string`</i> in
4681 the soapcpp2-generated schema:
4682 
4683 <div class="alt">
4684 ~~~{.xml}
4685  <simpleType name="Vowels">
4686  <annotation>
4687  <documentation>The letters A, E, I, O, U, and sometimes Y</documentation>
4688  </annotation>
4689  <restriction base="xsd:string">
4690  <enumeration value="A"/>
4691  <enumeration value="E"/>
4692  <enumeration value="I"/>
4693  <enumeration value="O"/>
4694  <enumeration value="U"/>
4695  <enumeration value="Y">
4696  <annotation>
4697  <documentation>A vowel, sometimes</documentation>
4698  </annotation>
4699  <enumeration/>
4700  </restriction>
4701  </simpleType>
4702 ~~~
4703 </div>
4704 
4705 🔝 [Back to table of contents](#)
4706 
4707 Serialization rules {#rules}
4708 ===================
4709 
4710 A presentation on XML data bindings is not complete without discussing the
4711 serialization rules and options that put your data in XML on the wire or store
4712 it a file or buffer.
4713 
4714 There are several options to choose from to serialize data in XML. The choice
4715 depends on the use of the SOAP protocol or if SOAP is not required. The wsdl2h
4716 tool automates this for you by taking the WSDL transport bindings into account
4717 when generating the service functions in C and C++ that use SOAP or REST.
4718 
4719 The gSOAP tools are not limited to SOAP. The tools implement generic XML data
4720 bindings for SOAP, REST, and other uses of XML. So you can read and write XML
4721 using the serializing [operations on classes and structs](#toxsd9-14).
4722 
4723 The following sections briefly explain the serialization rules with respect to
4724 the SOAP protocol for XML Web services. A basic understanding of the SOAP
4725 protocol is useful when developing client and server applications that must
4726 interoperate with other SOAP applications.
4727 
4728 SOAP/REST Web service client and service operations are represented as
4729 functions in your interface header file with the data binding interface for
4730 soapcpp2. The soapcpp2 tool will translate these function to client-side
4731 service invocation calls and server-side service operation dispatchers.
4732 
4733 A discussion of SOAP clients and servers is beyond the scope of this article.
4734 However, the SOAP options discussed here also apply to SOAP client and server
4735 development.
4736 
4737 🔝 [Back to table of contents](#)
4738 
4739 SOAP document versus rpc style {#doc-rpc}
4740 ------------------------------
4741 
4742 The `wsdl:binding/soap:binding/@style` attribute in the <i>`<wsdl:binding>`</i>
4743 section of a WSDL is either "document" or "rpc". The "rpc" style refers to
4744 SOAP RPC (Remote Procedure Call), which is more restrictive than the "document"
4745 style by requiring one XML element in the SOAP Body to act as the procedure
4746 name with XML subelements as its parameters.
4747 
4748 For example, the following directives in the interface header file for soapcpp2
4749 declare that `DBupdate` is a SOAP RPC encoding service method:
4750 
4751 ~~~{.cpp}
4752  //gsoap ns service namespace: urn:DB
4753  //gsoap ns service method-protocol: DBupdate SOAP
4754  //gsoap ns service method-style: DBupdate rpc
4755  int ns__DBupdate(...);
4756 ~~~
4757 
4758 The XML payload has a SOAP envelope, optional SOAP header, and a SOAP body with
4759 one element representing the operation with the parameters as subelements:
4760 
4761 <div class="alt">
4762 ~~~{.xml}
4763  <SOAP-ENV:Envelope
4764  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
4765  xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
4766  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4767  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
4768  xmlsn:ns="urn:DB">
4769  <SOAP-ENV:Body>
4770  <ns:DBupdate>
4771  ...
4772  </ns:DBupdate>
4773  </SOAP-ENV:Body>
4774  </SOAP-ENV:Envelope>
4775 ~~~
4776 </div>
4777 
4778 The "document" style puts no restrictions on the SOAP Body content. However, we
4779 recommend that the first element's tag name in the SOAP Body should be unique
4780 to each type of operation, so that the receiver can dispatch the operation
4781 based on this element's tag name. Alternatively, the HTTP URL path can be used
4782 to specify the operation, or the HTTP action header can be used to dispatch
4783 operations automatically on the server side (soapcpp2 options -a and -A).
4784 
4785 🔝 [Back to table of contents](#)
4786 
4787 SOAP literal versus encoding {#lit-enc}
4788 ----------------------------
4789 
4790 The `wsdl:operation/soap:body/@use` attribute in the <i>`<wsdl:binding>`</i> section
4791 of a WSDL is either "literal" or "encoded". The "encoded" use refers to the
4792 SOAP encoding rules that support id-ref multi-referenced elements to serialize
4793 data as graphs.
4794 
4795 SOAP encoding is very useful if the data internally forms a graph (including
4796 cycles) and we want the graph to be serialized in XML in a format that ensures
4797 that its structure is preserved. In that case, SOAP 1.2 encoding is the best
4798 option.
4799 
4800 SOAP encoding also adds encoding rules for [SOAP arrays](#toxsd10) to serialize
4801 multi-dimensional arrays. The use of XML attributes to exchange XML data in
4802 SOAP encoding is not permitted. The only attributes permitted are the standard
4803 XSD attributes, SOAP encoding attributes (such as for arrays), and id-ref.
4804 
4805 For example, the following directives in the interface header file for soapcpp2
4806 declare that `DBupdate` is a SOAP RPC encoding service method:
4807 
4808 ~~~{.cpp}
4809  //gsoap ns service namespace: urn:DB
4810  //gsoap ns service method-protocol: DBupdate SOAP
4811  //gsoap ns service method-style: DBupdate rpc
4812  //gsoap ns service method-encoding: DBupdate encoded
4813  int ns__DBupdate(...);
4814 ~~~
4815 
4816 The XML payload has a SOAP envelope, optional SOAP header, and a SOAP body with
4817 an encodingStyle attribute for SOAP 1.1 encoding and an element representing the
4818 operation with parameters that are SOAP 1.1 encoded:
4819 
4820 <div class="alt">
4821 ~~~{.xml}
4822  <SOAP-ENV:Envelope
4823  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
4824  xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
4825  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4826  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
4827  xmlsn:ns="urn:DB">
4828  <SOAP-ENV:Body SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
4829  <ns:DBupdate>
4830  <records SOAP-ENC:arrayType="ns:record[3]">
4831  <item>
4832  <name href="#_1"/>
4833  <SSN>1234567890</SSN>
4834  </item>
4835  <item>
4836  <name>Jane</name>
4837  <SSN>1987654320</SSN>
4838  </item>
4839  <item>
4840  <name href="#_1"/>
4841  <SSN>2345678901</SSN>
4842  </item>
4843  </records>
4844  </ns:DBupdate>
4845  <id id="_1" xsi:type="xsd:string">Joe</id>
4846  </SOAP-ENV:Body>
4847  </SOAP-ENV:Envelope>
4848 ~~~
4849 </div>
4850 
4851 In the XML fragment shown above the name "Joe" is shared by two records and the
4852 string is referenced by SOAP 1.1 href and id attributes.
4853 
4854 While the soapcpp-generated serializers only introduce multi-referenced
4855 elements in the payload when they are actually multi-referenced in the data
4856 graph, other SOAP applications may render multi-referenced elements more
4857 aggressively. The example could also be rendered as:
4858 
4859 <div class="alt">
4860 ~~~{.xml}
4861  <SOAP-ENV:Envelope
4862  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
4863  xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
4864  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4865  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
4866  xmlsn:ns="urn:DB">
4867  <SOAP-ENV:Body SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
4868  <ns:DBupdate>
4869  <records SOAP-ENC:arrayType="ns:record[3]">
4870  <item href="#id1"/>
4871  <item href="#id2"/>
4872  <item href="#id3"/>
4873  </records>
4874  </ns:DBupdate>
4875  <id id="id1" xsi:type="ns:record">
4876  <name href="#id4"/>
4877  <SSN>1234567890</SSN>
4878  </id>
4879  <id id="id2" xsi:type="ns:record">
4880  <name href="#id5"/>
4881  <SSN>1987654320</SSN>
4882  </id>
4883  <id id="id3" xsi:type="ns:record">
4884  <name href="#id4"/>
4885  <SSN>2345678901</SSN>
4886  </id>
4887  <id id="id4" xsi:type="xsd:string">Joe</id>
4888  <id id="id5" xsi:type="xsd:string">Jane</id>
4889  </SOAP-ENV:Body>
4890  </SOAP-ENV:Envelope>
4891 ~~~
4892 </div>
4893 
4894 SOAP 1.2 encoding is cleaner and produces more accurate XML encodings of data
4895 graphs by setting the id attribute on the element that is referenced:
4896 
4897 <div class="alt">
4898 ~~~{.xml}
4899  <SOAP-ENV:Envelope
4900  xmlns:SOAP-ENV="http://www.w3.org/2003/05/soap-envelope"
4901  xmlns:SOAP-ENC="http://www.w3.org/2003/05/soap-encoding"
4902  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4903  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
4904  xmlsn:ns="urn:DB">
4905  <SOAP-ENV:Body>
4906  <ns:DBupdate SOAP-ENV:encodingStyle="http://www.w3.org/2003/05/soap-encoding">
4907  <records SOAP-ENC:itemType="ns:record" SOAP-ENC:arraySize="3">
4908  <item>
4909  <name SOAP-ENC:id="_1">Joe</name>
4910  <SSN>1234567890</SSN>
4911  </item>
4912  <item>
4913  <name>Jane</name>
4914  <SSN>1987654320</SSN>
4915  </item>
4916  <item>
4917  <name SOAP-ENC:ref="_1"/>
4918  <SSN>2345678901</SSN>
4919  </item>
4920  </records>
4921  </ns:DBupdate>
4922  </SOAP-ENV:Body>
4923  </SOAP-ENV:Envelope>
4924 ~~~
4925 </div>
4926 
4927 @note Some SOAP 1.2 applications consider the namespace `SOAP-ENC` of
4928 <i>`SOAP-ENC:id`</i> and <i>`SOAP-ENC:ref`</i> optional. With gSOAP, the SOAP
4929 1.2 encoding serialization follows the 2007 standard, while accepting
4930 unqualified id and ref attributes.
4931 
4932 To remove all rendered id-ref multi-referenced elements, use the
4933 `SOAP_XML_TREE` flag to initialize the `soap` context.
4934 
4935 Some XSD validation rules are turned off with SOAP encoding, because of the
4936 presence of additional attributes, such as id and ref/href, SOAP arrays with
4937 arbitrary element tags for array elements, and the occurrence of additional
4938 multi-ref elements in the SOAP 1.1 Body.
4939 
4940 The use of "literal" puts no restrictions on the XML in the SOAP Body. Full
4941 XSD validation is possible, which can be enabled with the `SOAP_XML_STRICT`
4942 flag to initialize the `soap` context. However, data graphs will be
4943 serialized as trees and cycles in the data will be cut from the XML rendition.
4944 
4945 🔝 [Back to table of contents](#)
4946 
4947 SOAP 1.1 versus SOAP 1.2 {#soap}
4948 ------------------------
4949 
4950 There are two SOAP protocol versions: 1.1 and 1.2. The gSOAP tools can switch
4951 between the two versions seamlessly. You can declare the default SOAP version
4952 for a service operation as follows:
4953 
4954 ~~~{.cpp}
4955  //gsoap ns service method-protocol: DBupdate SOAP1.2
4956 ~~~
4957 
4958 Use `SOAP` (SOAP 1.1), `SOAP1.1`, `SOAP1.2`, and `HTTP` to switch SOAP versions
4959 or enable REST methods with HTTP POST. See [service directives](#directives-1)
4960 and [XML serialization](#non-soap).
4961 
4962 The soapcpp2 tool auto-generates client and server code. At the client side,
4963 this operation sends data with SOAP 1.2 but accepts responses also in SOAP 1.1.
4964 At the server side, this operation accepts requests in SOAP 1.1 and 1.2 and
4965 will return responses in the same SOAP version.
4966 
4967 As we discussed in the previous section, the SOAP 1.2 protocol has a cleaner
4968 multi-referenced element serialization format that greatly enhances the
4969 accuracy of data graph serialization with SOAP RPC encoding and is therefore
4970 recommended.
4971 
4972 The SOAP 1.2 protocol default can also be set by importing and loading
4973 <i>`gsoap/import/soap12.h`</i>:
4974 
4975 ~~~{.cpp}
4976  #import "soap12.h"
4977 ~~~
4978 
4979 Finally, the soapcpp2 tool has options to force SOAP 1.1, SOAP 1.2, or remove
4980 SOAP altogether with <b>`soapcpp2 -1`</b> (SOAP 1.1), <b>`soapcpp2 -2`</b>
4981 (SOAP 1.2) and <b>`soapcpp2 -0`</b> (plain XML, no SOAP).
4982 
4983 🔝 [Back to table of contents](#)
4984 
4985 XML serialization {#non-soap}
4986 -----------------
4987 
4988 You can serialize data to XML that is stored on the heap, on the stack (locals), and
4989 static data as long as the serializable (i.e. non-transient) values are
4990 properly initialized and pointers in the data structures are either NULL or
4991 point to valid structures.
4992 
4993 When XML is deserialized into data, the data is put on the heap and managed by the
4994 `::soap` context, see also [memory management](#memory).
4995 
4996 You can read and write XML directly to a file or stream with the serializing
4997 [operations on classes and structs](#toxsd9-14).
4998 
4999 To define and use XML Web service client and service operations, we can declare
5000 these operations in your interface header file with the data binding interface
5001 for soapcpp2 as functions. The function are translated by soapcpp2 to
5002 client-side service invocation calls and server-side service operation
5003 dispatchers.
5004 
5005 The REST operations POST, GET, and PUT are declared with `//gsoap` directives
5006 in the interface header file for soapcpp2. For example, a REST HTTP POST
5007 operation is declared as follows:
5008 
5009 ~~~{.cpp}
5010  //gsoap ns service namespace: urn:DB
5011  //gsoap ns service method-protocol: DBupdate POST
5012  int ns__DBupdate(...);
5013 ~~~
5014 
5015 There are no SOAP Envelope and SOAP Body elements in the payload for
5016 `DBupdate`. Also the XML serialization rules are identical to SOAP
5017 document/literal, meaning no SOAP RPC encoding XML structures are implicitly
5018 used. The XML payload only has the operation name as an element with its
5019 parameters serialized as subelements:
5020 
5021 <div class="alt">
5022 ~~~{.xml}
5023  <ns:DBupdate xmln:ns="urn:DB" ...>
5024  ...
5025  </ns:DBupdate>
5026 ~~~
5027 </div>
5028 
5029 To force id-ref serialization with REST similar to SOAP 1.2 multi-reference
5030 encoding, use the `SOAP_XML_GRAPH` flag to initialize the `soap` context.
5031 The XML serialization includes id and ref attributes for multi-referenced
5032 elements as follows:
5033 
5034 <div class="alt">
5035 ~~~{.xml}
5036  <ns:DBupdate xmln:ns="urn:DB" ...>
5037  <records>
5038  <item>
5039  <name id="_1">Joe</name>
5040  <SSN>1234567890</SSN>
5041  </item>
5042  <item>
5043  <name>Jane</name>
5044  <SSN>1987654320</SSN>
5045  </item>
5046  <item>
5047  <name ref="_1"/>
5048  <SSN>2345678901</SSN>
5049  </item>
5050  </records>
5051  </ns:DBupdate>
5052 ~~~
5053 </div>
5054 
5055 🔝 [Back to table of contents](#)
5056 
5057 Input and output {#io}
5058 ================
5059 
5060 Reading and writing XML from/to files, streams and string buffers is done via
5061 the managing `soap` context by setting one of the following context variables that
5062 control IO sources and sinks:
5063 
5064 ~~~{.cpp}
5065  soap->recvfd = fd; // an int file descriptor to read from (0 by default)
5066  soap->sendfd = fd; // an int file descriptor to write to (1 by default)
5067  soap->is = &is; // C++ only: a std::istream is object to read from
5068  soap->os = &os; // C++ only: a std::ostream os object to write to
5069  soap->is = cs; // C only: a const char* string to read from (soap->is will advance)
5070  soap->os = &cs; // C only: pointer to a const char*, will be set to point to the string output
5071 ~~~
5072 
5073 Normally, all of these context variables are NULL, which is required to send and
5074 receive data over sockets by gSOAP client and server applications. Therefore,
5075 if you set any of these context variables in a client or server application
5076 then you should reset them to NULL to ensure that socket communications are not
5077 blocked.
5078 
5079 @note The use of `soap::is` and `soap::os` in C requires gSOAP 2.8.28 or greater.
5080 
5081 In the following sections, we present more details on how to read and write to
5082 files and streams, and use string buffers as sources and sinks for XML data.
5083 
5084 In addition, you can set IO callback functions to handle IO at a lower level.
5085 For more details on defining your own callback functions, see the
5086 [gSOAP user guide.](../../guide/html/index.html)
5087 
5088 🔝 [Back to table of contents](#)
5089 
5090 Reading and writing from/to files and streams {#io1}
5091 ---------------------------------------------
5092 
5093 The default IO is standard input and output. Other sources and sinks (those
5094 listed above) will be used until you (re)set them. For example with file-based
5095 input and output:
5096 
5097 ~~~{.cpp}
5098  FILE *fp = fopen("record.xml", "r");
5099  if (fp != NULL)
5100  {
5101  soap->recvfd = fileno(fp); // get file descriptor of file to read from
5102  if (soap_read_ns__record(soap, &pers1))
5103  ... // handle IO error
5104  fclose(fp);
5105  soap->recvfd = 0; // read from stdin, or -1 to block reading
5106  }
5107 
5108  FILE *fp = fopen("record.xml", "w");
5109  if (fp != NULL)
5110  {
5111  soap->sendfd = fileno(fp); // get file descriptor of file to write to
5112  if (soap_write_ns__record(soap, &pers1))
5113  ... // handle IO error
5114  fclose(fp);
5115  soap->sendfd = 1; // write to stdout, or -1 to block writing
5116  }
5117 ~~~
5118 
5119 Similar code with streams in C++:
5120 
5121 ~~~{.cpp}
5122  #include <fstream>
5123 
5124  std::fstream fs;
5125  fs.open("record.xml", std::ios::in);
5126  if (fs)
5127  {
5128  soap->is = &fs;
5129  if (soap_read__ns__record(soap, &pers1))
5130  ... // handle IO error
5131  fs.close();
5132  soap->is = NULL;
5133  }
5134 
5135  fs.open("record.xml", std::ios::out);
5136  if (fs)
5137  {
5138  soap->os = &fs;
5139  if (soap_write__ns__record(soap, &pers1))
5140  ... // handle IO error
5141  fs.close();
5142  soap->os = NULL;
5143  }
5144 ~~~
5145 
5146 🔝 [Back to table of contents](#)
5147 
5148 Reading and writing from/to string buffers {#io2}
5149 ------------------------------------------
5150 
5151 For C++ we recommend to use `std::stringstream` objects from the
5152 <i>`sstream`</i> C++ library as illustrated in the following example:
5153 
5154 ~~~{.cpp}
5155  #include <sstream>
5156 
5157  std::stringstream ss;
5158  ss.str("..."); // XML to parse
5159  soap->is = &ss;
5160  if (soap_read__ns__record(soap, &pers1))
5161  ... // handle IO error
5162  soap->is = NULL;
5163 
5164  soap->os = &ss;
5165  if (soap_write__ns__record(soap, &pers1))
5166  ... // handle IO error
5167  soap->os = NULL;
5168  std::string s = ss.str(); // string with XML
5169 ~~~
5170 
5171 For C we can use `soap::is` and `soap::os` to point to strings of XML content
5172 as follows (this requires gSOAP 2.8.28 or later):
5173 
5174 ~~~{.cpp}
5175  soap->is = "..."; // XML to parse
5176  if (soap_read__ns__record(soap, &pers1))
5177  ... // handle IO error
5178  soap->is = NULL;
5179 
5180  const char *cs = NULL;
5181  soap->os = &cs;
5182  if (soap_write__ns__record(soap, &pers1))
5183  ... // handle IO error
5184  soap->os = NULL;
5185  ... = cs; // string with XML (do not free(cs): managed by the context and freed with soap_end())
5186 ~~~
5187 
5188 The type of `soap::os` is a pointer to a `const char*` string. The pointer is
5189 set by the managing `soap` context to point to the XML data that is stored on
5190 the context-managed heap.
5191 
5192 For earlier gSOAP versions we recommend to use IO callbacks `soap::frecv` and
5193 `soap::fsend`, see the [gSOAP user guide.](../../guide/html/index.html).
5194 
5195 🔝 [Back to table of contents](#)
5196 
5197 Memory management {#memory}
5198 =================
5199 
5200 Memory management with the `soap` context enables us to allocate data in
5201 context-managed heap space that can be collectively deleted. All deserialized
5202 data is placed on the context-managed heap by the `soap` context of the engine.
5203 
5204 🔝 [Back to table of contents](#)
5205 
5206 Memory management in C {#memory1}
5207 ----------------------
5208 
5209 When working with gSOAP in C (i.e. using <b>`wsdl2h -c`</b> option <b>`-c`</b>
5210 or <b>`soapcpp2 -c`</b> option <b>`-c`</b>), data is allocated on the managed heap with:
5211 
5212 - `void *soap_malloc(struct soap*, size_t len)`.
5213 
5214 This function allocates `len` bytes on the heap managed by the specified
5215 context and returns NULL when allocation failed.
5216 
5217 You can also make shallow copies of data with `soap_memdup` that uses
5218 `soap_malloc` and a safe version of `memcpy` to copy a chunk of data `src` with
5219 length `len` to the context-managed heap:
5220 
5221 - `void * soap_memdup(struct soap*, const void *src, size_t len)`
5222 
5223 This function returns a pointer to the copy. This function requires gSOAP
5224 2.8.27 or later.
5225 
5226 In gSOAP 2.8.35 and greater versions, you can use an auto-generated function to
5227 allocate and initialize data of type `T` on the managed heap:
5228 
5229 - `T * soap_new_T(struct soap*, int n)`
5230 
5231 This function returns an array of length `n` of type `T` data that is default
5232 initialized (by internally calling `soap_malloc(soap, n * sizeof(T))` and then
5233 `soap_default_T(soap, T*)` on each array value). Use a negative value or `n=1`
5234 to allocate and initialize a single value. This function returns NULL when
5235 allocation failed.
5236 
5237 The `soap_malloc` function is essentially a wrapper around `malloc`, but
5238 permits the `soap` context to track all heap allocations for collective
5239 deletion with `soap_end(soap)`:
5240 
5241 ~~~{.cpp}
5242  #include "soapH.h"
5243  #include "ns.nsmap"
5244  ...
5245  struct soap *soap = soap_new(); // new context
5246  ...
5247  struct ns__record *record = (struct ns__record*)soap_malloc(soap, sizeof(struct ns__record));
5248  soap_default_ns__record(soap, record); // auto-generated struct initializer
5249  ...
5250  soap_destroy(soap); // only for C++, see section on C++ below
5251  soap_end(soap); // delete record and all other heap allocations
5252  soap_free(soap); // delete context
5253 ~~~
5254 
5255 All data on the managed heap is mass-deleted with `soap_end(soap)` which must
5256 be called before `soap_done(soap)` or `soap_free(soap)`, which end the use of
5257 the `soap` context and free the context, respectively. Use
5258 `soap_free(soap)` only when the context is allocated with `soap_new()`. Use
5259 `soap_done(soap)` only when the context is stack allocated (so cannot be
5260 deleted from the heap).
5261 
5262 The managed heap is checked for memory leaks at run time when the source code
5263 is compiled with option <b>`-DDEBUG`</b>.
5264 
5265 The soapcpp2 auto-generated deserializers in C use `soap_malloc` to allocate
5266 and populate deserialized structures, which are managed by the context for
5267 collective deletion.
5268 
5269 To make `char*` and `wchar_t*` string copies to the context-managed heap, we
5270 can use the functions:
5271 
5272 - `char *soap_strdup(struct soap*, const char *str)` and
5273 
5274 - `wchar_t *soap_wstrdup(struct soap*, const wchar_t *wstr)`.
5275 
5276 If your C compiler supports `typeof` then you can use the following macro to
5277 simplify the managed heap allocation and initialization of primitive values:
5278 
5279 ~~~{.cpp}
5280  #define soap_assign(soap, lhs, rhs) (*(lhs = (typeof(lhs))soap_malloc(soap, sizeof(*lhs))) = rhs)
5281 ~~~
5282 
5283 Pointers to primitive values are often used for optional members. For example,
5284 assume we have the following struct:
5285 
5286 ~~~{.cpp}
5287  struct ns__record
5288  {
5289  const char *name 1; // required (minOccurs=1)
5290  uint64_t *SSN; // optional (pointer means minOccurs=0)
5291  struct ns__record *spouse; // optional (pointer means minOccurs=0)
5292  };
5293 ~~~
5294 
5295 Use `soap_assign` to create a SSN value on the managed heap:
5296 
5297 ~~~{.cpp}
5298  struct soap *soap = soap_new(); // new context
5299  ...
5300  struct ns__record *record = (struct ns__record*)soap_malloc(soap, sizeof(struct ns__record));
5301  soap_default_ns__record(soap, record);
5302  record->name = soap_strdup(soap, "Joe");
5303  soap_assign(soap, record->SSN, 1234567890UL);
5304  ...
5305  soap_end(soap); // delete managed soap_malloc'ed heap data
5306  soap_free(soap); // delete context
5307 ~~~
5308 
5309 Without the `soap_assign` macro, you will need two lines of code, one to
5310 allocate and one to assign (you should also use this if your system can run out
5311 of memory):
5312 
5313 ~~~{.cpp}
5314  assert((record->SSN = (uint64_t*)soap_malloc(soap, sizeof(utint64_t))) != NULL);
5315  *record->SSN = 1234567890UL;
5316 ~~~
5317 
5318 The serializer can serialize any heap, stack, or static allocated data. So we
5319 can also create a new record as follows:
5320 
5321 ~~~{.cpp}
5322  struct soap *soap = soap_new(); // new context
5323  ...
5324  struct ns__record *record = (struct ns__record*)soap_malloc(soap, sizeof(struct ns__record));
5325  static uint64_t SSN = 1234567890UL;
5326  soap_default_ns__record(soap, record);
5327  record->name = "Joe";
5328  record->SSN = &SSN; // safe to use static values: the value of record->SSN is never changed
5329  ...
5330  soap_end(soap); // delete managed soap_malloc'ed heap data
5331  soap_free(soap); // delete context
5332 ~~~
5333 
5334 Use the soapcpp2 auto-generated `soap_dup_T` functions to duplicate data into
5335 another `soap` context (this requires <b>`soapcpp2 -Ec`</b> option <b>`-Ec`</b> to
5336 generate), here shown for C with the second argument `dst` NULL because we want
5337 to allocate a new managed structure:
5338 
5339 ~~~{.cpp}
5340  struct soap *other_soap = soap_new(); // another context
5341  struct ns__record *other_record = soap_dup_ns__record(other_soap, NULL, record);
5342  ...
5343  soap_destroy(other_soap); // only for C++, see section on C++ below
5344  soap_end(other_soap); // delete other_record and all of its deep data
5345  soap_free(other_soap); // delete context
5346 ~~~
5347 
5348 The only reason to use another `soap` context and not to use the primary `soap`
5349 context is when the primary context must be destroyed together with all of the
5350 objects it manages while some of the objects must be kept alive. If the
5351 objects that are kept alive contain deep cycles then this is the only option we
5352 have, because deep copy with a managing `soap` context detects and preserves
5353 these cycles unless the `SOAP_XML_TREE` flag is used with the `soap` context:
5354 
5355 ~~~{.cpp}
5356  struct soap *other_soap = soap_new1(SOAP_XML_TREE); // another context
5357  struct ns__record *other_record = soap_dup_ns__record(other_soap, NULL, record);
5358 ~~~
5359 
5360 The resulting deep copy will be a full copy of the source data structure as a
5361 tree without co-referenced data (i.e. no digraph) and without cycles. Cycles
5362 are pruned and (one of the) pointers that forms a cycle is repaced by NULL.
5363 
5364 You can also deep copy into unmanaged space and use the auto-generated
5365 `soap_del_T()` function (requires <b>`soapcpp2 -Ed`</b> option <b>`-Ed`</b> to generate) to delete
5366 it later:
5367 
5368 ~~~{.cpp}
5369  struct ns__record *other_record = soap_dup_ns__record(NULL, NULL, record);
5370  ...
5371  soap_del_ns__record(other_record); // deep delete record data members
5372  free(other_record); // delete the record
5373 ~~~
5374 
5375 But you should not do this for any data that has deep cycles in its runtime
5376 data structure. Cycles in the data structure will lead to non-termination when
5377 making unmanaged deep copies. Consider for example:
5378 
5379 ~~~{.cpp}
5380  struct ns__record
5381  {
5382  const char *name 1; // required (minOccurs=1)
5383  uint64_t SSN; // required (non-pointer means minOccurs=1)
5384  struct ns__record *spouse; // optional (pointer means minOccurs=0)
5385  };
5386 ~~~
5387 
5388 The code to populate a structure with a mutual spouse relationship:
5389 
5390 ~~~{.cpp}
5391  struct soap *soap = soap_new();
5392  ...
5393  struct ns__record pers1, pers2;
5394  soap_default_ns__record(soap, &pers1);
5395  soap_default_ns__record(soap, &pers2);
5396  pers1.name = "Joe"; // OK to serialize static data
5397  pers1.SSN = 1234567890;
5398  pers1.spouse = &pers2;
5399  pers2.name = soap_strdup(soap, "Jane"); // allocates and copies a string
5400  pers2.SSN = 1987654320;
5401  pers2.spouse = &pers1;
5402  ...
5403  struct ns__record *pers3 = soap_dup_ns__record(NULL, NULL, &pers1); // BAD
5404  struct ns__record *pers4 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5405  soap_set_mode(soap, SOAP_XML_TREE);
5406  struct ns__record *pers5 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5407 ~~~
5408 
5409 The bad case is where there is no context used in the first argument. The deep
5410 copy functions use a context to keep track of co-referenced data nodes and
5411 cycles in the data structure copies, to copy co-referenced nodes just once.
5412 Co-references in a data structure are formed by pointers and smart pointers
5413 such as `std::shared_ptr`, such that at least two pointers point to the same
5414 data.
5415 
5416 The serializer can serialize any heap, stack, or static allocated data, such as
5417 in the code shown above. So we can serialize the stack-allocated `pers1`
5418 record as follows:
5419 
5420 ~~~{.cpp}
5421  FILE *fp = fopen("record.xml", "w");
5422  if (fp != NULL)
5423  {
5424  soap->sendfd = fileno(fp); // file descriptor to write to
5425  soap_set_mode(soap, SOAP_XML_GRAPH); // support id-ref w/o requiring SOAP
5426  soap_clr_mode(soap, SOAP_XML_TREE); // if set, clear
5427  soap_write_ns__record(soap, &pers1);
5428  fclose(fp);
5429  soap->sendfd = -1; // block further writing
5430  }
5431 ~~~
5432 
5433 which produces an XML document record.xml that is similar to:
5434 
5435 <div class="alt">
5436 ~~~{.xml}
5437  <ns:record xmlns:ns="urn:types" id="Joe">
5438  <name>Joe</name>
5439  <SSN>1234567890</SSN>
5440  <spouse id="Jane">
5441  <name>Jane</name>
5442  <SSN>1987654320</SSN>
5443  <spouse ref="#Joe"/>
5444  </spouse>
5445  </ns:record>
5446 ~~~
5447 </div>
5448 
5449 Deserialization of an XML document with a SOAP 1.1/1.2 encoded id-ref graph
5450 leads to the same non-termination problem when we later try to copy the data
5451 into unmanaged memory heap space:
5452 
5453 ~~~{.cpp}
5454  struct soap *soap = soap_new1(SOAP_XML_GRAPH); // support id-ref w/o SOAP
5455  ...
5456  struct ns__record pers1;
5457  FILE *fp = fopen("record.xml", "r");
5458  if (fp != NULL)
5459  {
5460  soap->recvfd = fileno(fp);
5461  if (soap_read_ns__record(soap, &pers1))
5462  ... // handle IO error
5463  fclose(fp);
5464  soap->recvfd = -1; // blocks further reading
5465  }
5466  ...
5467  struct ns__record *pers3 = soap_dup_ns__record(NULL, NULL, &pers1); // BAD
5468  struct ns__record *pers4 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5469  soap_set_mode(soap, SOAP_XML_TREE);
5470  struct ns__record *pers5 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5471 ~~~
5472 
5473 Copying data with `soap_dup_T(soap)` into managed heap memory space is always
5474 safe. Copying into unmanaged heap memory space requires diligence. But
5475 deleting unmanaged data is easy with `soap_del_T()`.
5476 
5477 You can also use `soap_del_T()` to delete structures that you created in C, but
5478 only if these structures are created with `malloc` and do NOT contain pointers
5479 to stack and static data.
5480 
5481 You can unlink one or more allocated objects from the managed heap to allow the
5482 object to live after `soap_end(soap)` by using:
5483 
5484 - `void soap_unlink(struct soap *soap, void *ptr)`
5485 
5486 The unlinked heap-allocated data pointed to by `ptr` can be accessed after
5487 `soap_end(soap)`. Do not forget to free the data with `free(ptr)`. Be aware
5488 that `soap_unlink(soap, ptr)` does not perform a deep unlinkage. If `ptr` is a
5489 struct, pointer members will become invalid when pointing to objects on the
5490 managed heap. Use `soap_unlink(soap, ptr->member)` to unlink `member` as well.
5491 
5492 Finally, when data is allocated in managed memory heap space, either explicitly
5493 with the allocation functions shown above or by the soapcpp2-generated
5494 deserializers, you can delegate the management and deletion of this data to
5495 another `soap` context. That context will be responsible to delete the data
5496 with `soap_end(soap)` later:
5497 
5498 - `void delegate_deletion(struct soap *soap_from, struct soap *soap_to)`
5499 
5500 This allows the `soap_from` context to be deleted with `soap_free(soap_from)`
5501 (assuming it is allocated with `soap_new()`, use `soap_done(soap_from)` when
5502 `soap_from` is stack-allocated) while the managed data remains intact. You
5503 can use this function any time, to delegate management and deletion to another
5504 context `soap_to` and then continue with the current context. You can also use
5505 different source `soap_from` contexts to delegate management and deletion to
5506 the other `soap_to` context. To mass delete all managed data, use
5507 `soap_end(soap_to)`.
5508 
5509 🔝 [Back to table of contents](#)
5510 
5511 Memory management in C++ {#memory2}
5512 ------------------------
5513 
5514 When working with gSOAP in C++, the engine allocates data on a managed heap
5515 using `soap_new_T(soap)` to allocate a type with type name `T`. Managed heap
5516 allocation is tracked by the `soap` context for collective deletion with
5517 `soap_destroy(soap)` for structs, classes, and templates and with
5518 `soap_end(soap)` for everything else.
5519 
5520 You should only use `soap_malloc(struct soap*, size_t len)` to allocate
5521 primitive types because constructors are not invoked. Therefore, `soap_new_T`
5522 is preferred. The auto-generated `T * soap_new_T(struct soap*)` returns data
5523 allocated on the managed heap for type `T`. The data is mass-deleted with
5524 `soap_destroy(soap)` followed by `soap_end(soap)`.
5525 
5526 The `soap_new_T` functions return NULL when allocation fails. C++ exceptions
5527 are never raised by the engine and serializers when data is allocated.
5528 
5529 There are four variations of `soap_new_T` functions to allocate data of type
5530 `T` that soapcpp2 auto-generates:
5531 
5532 - `T * soap_new_T(struct soap*)` returns a new instance of `T` that is default
5533  initialized. For classes, initialization is internally performed using the
5534  soapcpp2 auto-generated `void T::soap_default(struct soap*)` method of the
5535  class, but ONLY IF the soapcpp2 auto-generated default constructor is used
5536  that invokes `soap_default()` and was not replaced by a user-defined default
5537  constructor.
5538 
5539 - `T * soap_new_T(struct soap*, int n)` returns an array of `n` new instances of
5540  `T`. The instances in the array are default initialized as described above.
5541 
5542 - `T * soap_new_req_T(struct soap*, ...)` (structs and classes only) returns a
5543  new instance of `T` and sets the required data members to the values
5544  specified in `...`. The required data members are those with nonzero
5545  minOccurs, see the subsections on
5546  [(smart) pointer members and their occurrence constraints](#toxsd9-8) and
5547  [container and array members and their occurrence constraints](#toxsd9-9).
5548 
5549 - `T * soap_new_set_T(struct soap*, ...)` (structs and classes only) returns a
5550  new instance of `T` and sets the public/serializable data members to the values
5551  specified in `...`.
5552 
5553 The above functions can be invoked with a NULL `soap` context, but you are then
5554 responsible to use `delete T` to remove this instance from the unmanaged heap.
5555 
5556 For example, to allocate a managed `std::string` you can use:
5557 
5558 ~~~{.cpp}
5559  std::string *s = soap_new_std__string(soap);
5560 ~~~
5561 
5562 To throw a `std::bad_alloc` exception when memory allocation fails, we can define the
5563 following class and macro:
5564 
5565 ~~~{.cpp}
5566  class alloc_check {
5567  public:
5568  template<typename T>
5569  T operator=(T ptr)
5570  {
5571  if (ptr == NULL)
5572  throw std::bad_alloc();
5573  return ptr;
5574  }
5575  };
5576 
5577  #define CHECK alloc_check() =
5578 ~~~
5579 
5580 And use `CHECK` as follows to throw an exception when memory allocation fails:
5581 
5582 ~~~{.cpp}
5583  std::string *s = CHECK soap_new_std__string(soap);
5584 ~~~
5585 
5586 To throw a `std::runtime_exception` when memory allocation fails, with file
5587 and line number information where the error occurred, we can define the
5588 following revised version of our exception-throwing macro:
5589 
5590 ~~~{.cpp}
5591  class alloc_failure : public std::runtime_error {
5592  public:
5593  alloc_failure(const char *file, size_t line) : std::runtime_error(error(file, line))
5594  { }
5595  private:
5596  std::string error(const char *file, size_t line) const
5597  {
5598  std::stringstream ss;
5599  ss << "Memory allocation failed in " << file << " at line " << line;
5600  return ss.str();
5601  }
5602  };
5603 
5604  class alloc_check_with_info {
5605  public:
5606  alloc_check_with_info(const char *file, size_t line) : file(file), line(line)
5607  { }
5608  template<typename T>
5609  T operator=(T ptr) const
5610  {
5611  if (ptr == NULL)
5612  throw alloc_failure(file, line);
5613  return ptr;
5614  }
5615  const char *file;
5616  size_t line;
5617  };
5618 
5619  #define CHECK alloc_check_with_info(__FILE__, __LINE__) =
5620 ~~~
5621 
5622 And use `CHECK` as follows to throw an exception with the file and line number
5623 of the location where memory allocation failed:
5624 
5625 ~~~{.cpp}
5626  std::string *s = CHECK soap_new_std__string(soap);
5627 ~~~
5628 
5629 Primitive types and arrays of primitive values may be allocated with
5630 `soap_malloc` (actually, `soap_new_T` calls `soap_malloc` for primitive type
5631 `T`). All primitive types (i.e. no classes, structs, class templates,
5632 containers, and smart pointers) are allocated with `soap_malloc` for reasons of
5633 efficiency.
5634 
5635 You can use a C++ template to simplify the managed allocation and initialization
5636 of primitive values as follows (this is for primitive types only):
5637 
5638 ~~~{.cpp}
5639  template<class T>
5640  T * soap_make(struct soap *soap, T val)
5641  {
5642  T *p = (T*)soap_malloc(soap, sizeof(T));
5643  if (p == NULL)
5644  throw std::bad_alloc();
5645  *p = val;
5646  return p;
5647  }
5648 ~~~
5649 
5650 For example, assuming we have the following class:
5651 
5652 ~~~{.cpp}
5653  class ns__record
5654  {
5655  public:
5656  std::string name; // required (non-pointer means minOccurs=1)
5657  uint64_t *SSN; // optional (pointer means minOccurs=0)
5658  ns__record *spouse; // optional (pointer means minOccurs=0)
5659  };
5660 ~~~
5661 
5662 You can instantiate a record by using the auto-generated
5663 `soap_new_set_ns__record` and use `soap_make` to create a SSN value on the
5664 managed heap as follows:
5665 
5666 ~~~{.cpp}
5667  soap *soap = soap_new(); // new context
5668  ...
5669  ns__record *record = soap_new_set_ns__record(
5670  soap,
5671  "Joe",
5672  soap_make<uint64_t>(soap, 1234567890UL),
5673  NULL);
5674  ...
5675  soap_destroy(soap); // delete record and all other managed instances
5676  soap_end(soap); // delete managed soap_malloc'ed heap data
5677  soap_free(soap); // delete context
5678 ~~~
5679 
5680 All data on the managed heap is mass-deleted with `soap_end(soap)` which must
5681 be called before `soap_done(soap)` or `soap_free(soap)`, which end the use of
5682 the `soap` context and free the context, respectively. Use
5683 `soap_free(soap)` only when the context is allocated with `soap_new()`. Use
5684 `soap_done(soap)` only when the context is stack allocated (so cannot be
5685 deleted from the heap).
5686 
5687 The managed heap is checked for memory leaks at run time when the source code
5688 is compiled with option <b>`-DDEBUG`</b>.
5689 
5690 However, the serializer can serialize any heap, stack, or static allocated
5691 data. So we can also create a new record as follows:
5692 
5693 ~~~{.cpp}
5694  uint64_t SSN = 1234567890UL;
5695  ns__record *record = soap_new_set_ns__record(soap, "Joe", &SSN, NULL);
5696 ~~~
5697 
5698 which will be fine to serialize this record as long as the local `SSN`
5699 stack-allocated value remains in scope when invoking the serializer and/or
5700 using `record`. It does not matter if `soap_destroy` and `soap_end` are called
5701 beyond the scope of `SSN`.
5702 
5703 To facilitate class methods to access the managing context, we can add a soap
5704 context pointer to a class/struct:
5705 
5706 ~~~{.cpp}
5707  class ns__record
5708  {
5709  public:
5710  ...
5711  void create_more(); // needs a context to create more internal data
5712  protected:
5713  struct soap *soap; // the context that manages this instance, or NULL
5714  };
5715 ~~~
5716 
5717 The `soap` context pointer member of the class is set when invoking
5718 `soap_new_T` (and similar) with a non-NULL context argument that will be
5719 assigned to the `soap` member of the class.
5720 
5721 You can also use a template when an array of pointers to values is required.
5722 To create an array of pointers to values, define the following template:
5723 
5724 ~~~{.cpp}
5725  template<class T>
5726  T **soap_make_array(struct soap *soap, T* array, int n) throw (std::bad_alloc)
5727  {
5728  T **p = (T**)soap_malloc(soap, n * sizeof(T*));
5729  if (p == NULL)
5730  throw std::bad_alloc();
5731  for (int i = 0; i < n; ++i)
5732  p[i] = &array[i];
5733  return p;
5734  }
5735 ~~~
5736 
5737 The `array` parameter is a pointer to an array of `n` values. The template
5738 returns an array of `n` pointers that point to the values in that array:
5739 
5740 ~~~{.cpp}
5741  // create an array of 100 pointers to 100 records
5742  int n = 100;
5743  ns__record **precords = soap_make_array(soap, soap_new_ns__record(soap, n), n);
5744  for (int i = 0; i < n; ++i)
5745  {
5746  precords[i]->name = "...";
5747  precords[i]->SSN = soap_make<uint64_t>(1234567890UL + i);
5748  }
5749 ~~~
5750 
5751 Note that `soap_new_ns__record(soap, n)` returns a pointer to an array of `n`
5752 records, which is then used to create an array of `n` pointers to these records.
5753 
5754 Use the soapcpp2 auto-generated `soap_dup_T` functions to duplicate data into
5755 another `soap` context (this requires <b>`soapcpp2 -Ec`</b> option <b>`-Ec`</b> to generate), here shown
5756 for C++ with the second argument `dst` NULL to allocate a new managed object:
5757 
5758 ~~~{.cpp}
5759  soap *other_soap = soap_new(); // another context
5760  ns__record *other_record = soap_dup_ns__record(other_soap, NULL, record);
5761  ...
5762  soap_destroy(other_soap); // delete record and other managed instances
5763  soap_end(other_soap); // delete other data (the SSNs on the heap)
5764  soap_free(other_soap); // delete context
5765 ~~~
5766 
5767 To duplicate base and derived instances when a base class pointer or reference
5768 is provided, use the auto-generated method `T * T::soap_dup(struct soap*)`:
5769 
5770 ~~~{.cpp}
5771  soap *other_soap = soap_new(); // another context
5772  ns__record *other_record = record->soap_dup(other_soap);
5773  ...
5774  soap_destroy(other_soap); // delete record and other managed instances
5775  soap_end(other_soap); // delete other data (the SSNs on the heap)
5776  soap_free(other_soap); // delete context
5777 ~~~
5778 
5779 The only reason to use another context and not to use the primary `soap`
5780 context is when the primary context must be destroyed together with all of the
5781 objects it manages while some of the objects must be kept alive. If the
5782 objects that are kept alive contain deep cycles then this is the only option we
5783 have, because deep copy with a managing `soap` context detects and preserves
5784 these cycles unless the `SOAP_XML_TREE` flag is used with the context:
5785 
5786 ~~~{.cpp}
5787  soap *other_soap = soap_new1(SOAP_XML_TREE); // another context
5788  ns__record *other_record = record->soap_dup(other_soap); // deep tree copy
5789 ~~~
5790 
5791 The resulting deep copy will be a full copy of the source data structure as a
5792 tree without co-referenced data (i.e. no digraph) and without cycles. Cycles
5793 are pruned and (one of the) pointers that forms a cycle is repaced by NULL.
5794 
5795 You can also deep copy into unmanaged space and use the auto-generated
5796 `soap_del_T()` function or the `T::soap_del()` method (requires
5797 <b>`soapcpp2 -Ec`</b> option <b>`-Ec`</b> to generate) to delete it later,
5798 but we should not do this for any data that has deep cycles in its runtime data
5799 structure graph:
5800 
5801 ~~~{.cpp}
5802  ns__record *other_record = record->soap_dup(NULL);
5803  ...
5804  other_record->soap_del(); // deep delete record data members
5805  delete other_record; // delete the record
5806 ~~~
5807 
5808 Cycles in the data structure will lead to non-termination when making unmanaged
5809 deep copies. Consider for example:
5810 
5811 ~~~{.cpp}
5812  class ns__record
5813  {
5814  public:
5815  const char *name 1; // required (minOccurs=1)
5816  uint64_t SSN; // required (non-pointer means minOccurs=1)
5817  ns__record *spouse; // optional (pointer means minOccurs=1)
5818  };
5819 ~~~
5820 
5821 The code to populate a structure with a mutual spouse relationship:
5822 
5823 ~~~{.cpp}
5824  soap *soap = soap_new();
5825  ...
5826  ns__record pers1, pers2;
5827  pers1.name = "Joe";
5828  pers1.SSN = 1234567890;
5829  pers1.spouse = &pers2;
5830  pers2.name = "Jane";
5831  pers2.SSN = 1987654320;
5832  pers2.spouse = &pers1;
5833  ...
5834  ns__record *pers3 = soap_dup_ns__record(NULL, NULL, &pers1); // BAD
5835  ns__record *pers4 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5836  soap_set_mode(soap, SOAP_XML_TREE);
5837  ns__record *pers5 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5838 ~~~
5839 
5840 The serializer can serialize any heap, stack, or static allocated data, such as
5841 shown in the code shown above. So we can serialize the stack-allocated `pers1`
5842 record as follows:
5843 
5844 ~~~{.cpp}
5845  FILE *fp = fopen("record.xml", "w");
5846  if (fp != NULL)
5847  {
5848  soap->sendfd = fileno(fp); // file descriptor to write to
5849  soap_set_mode(soap, SOAP_XML_GRAPH); // support id-ref w/o requiring SOAP
5850  soap_clr_mode(soap, SOAP_XML_TREE); // if set, clear
5851  if (soap_write_ns__record(soap, &pers1))
5852  ... // handle IO error
5853  fclose(fp);
5854  soap->sendfd = -1; // block further writing
5855  }
5856 ~~~
5857 
5858 which produces an XML document record.xml that is similar to:
5859 
5860 <div class="alt">
5861 ~~~{.xml}
5862  <ns:record xmlns:ns="urn:types" id="Joe">
5863  <name>Joe</name>
5864  <SSN>1234567890</SSN>
5865  <spouse id="Jane">
5866  <name>Jane</name>
5867  <SSN>1987654320</SSN>
5868  <spouse ref="#Joe"/>
5869  </spouse>
5870  </ns:record>
5871 ~~~
5872 </div>
5873 
5874 Deserialization of an XML document with a SOAP 1.1/1.2 encoded id-ref graph
5875 leads to the same non-termination problem when we later try to copy the data
5876 into unmanaged space:
5877 
5878 ~~~{.cpp}
5879  soap *soap = soap_new1(SOAP_XML_GRAPH); // support id-ref w/o SOAP
5880  ...
5881  ns__record pers1;
5882  FILE *fp = fopen("record.xml", "r");
5883  if (fp != NULL)
5884  {
5885  soap->recvfd = fileno(fp); // file descriptor to read from
5886  if (soap_read_ns__record(soap, &pers1))
5887  ... // handle IO error
5888  fclose(fp);
5889  soap->recvfd = -1; // block further reading
5890  }
5891  ...
5892  ns__record *pers3 = soap_dup_ns__record(NULL, NULL, &pers1); // BAD
5893  ns__record *pers4 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5894  soap_set_mode(soap, SOAP_XML_TREE);
5895  ns__record *pers5 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5896 ~~~
5897 
5898 Copying data with `soap_dup_T(soap)` into managed space is always safe. Copying
5899 into unmanaged space requires diligence. But deleting unmanaged data is easy
5900 with `soap_del_T()`.
5901 
5902 You can also use `soap_del_T()` to delete structures in C++, but only if these
5903 structures are created with `new` (and `new []` for arrays when applicable) for
5904 classes, structs, and class templates and with `malloc` for anything else, and
5905 the structures do NOT contain pointers to stack and static data.
5906 
5907 You can unlink one or more allocated objects from the managed heap to allow the
5908 object to live after `soap_destroy(soap)` and `soap_end(soap)` by using:
5909 
5910 - `void soap_unlink(struct soap *soap, void *ptr)`
5911 
5912 The unlinked heap-allocated data pointed to by `ptr` can be accessed after
5913 `soap_destroy(soap)` and `soap_end(soap)`. Do not forget to free the data with
5914 `delete ptr` (C++ class instance only) or with `free(ptr)` (non-class data).
5915 Be aware that `soap_unlink(soap, ptr)` does not perform a deep unlinkage. If
5916 `ptr` is a struct or class, pointer members will become invalid when pointing
5917 to objects on the managed heap. Use `soap_unlink(soap, ptr->member)` to unlink
5918 `member` as well.
5919 
5920 Finally, when data is allocated in managed memory heap space, either explicitly
5921 with the allocation functions shown above or by the soapcpp2-generated
5922 deserializers, you can delegate the management and deletion of this data to
5923 another `soap` context. That context will be responsible to delete the data
5924 with `soap_destroy(soap)` and `soap_end(soap)` later:
5925 
5926 - `void delegate_deletion(struct soap *soap_from, struct soap *soap_to)`
5927 
5928 This allows the `soap_from` context to be deleted with `soap_free(soap_from)`
5929 (assuming it is allocated with `soap_new()`, use `soap_done(soap_from)` when
5930 `soap_from` is stack-allocated) while the managed data remains intact. You
5931 can use this function any time, to delegate management and deletion to another
5932 context `soap_to` and then continue with the current context. You can also use
5933 different source `soap_from` contexts to delegate management and deletion to
5934 the other `soap_to` context. To mass delete all managed data, use
5935 `soap_destroy(soap_to)` followed by `soap_end(soap_to)`.
5936 
5937 🔝 [Back to table of contents](#)
5938 
5939 Context flags to initialize the soap struct {#flags}
5940 ===========================================
5941 
5942 There are several `soap` context initialization flags and context mode flags to
5943 control XML serialization at runtime. The flags are set with `soap_new1()` to
5944 allocate and initialize a new context:
5945 
5946 ~~~{.cpp}
5947  struct soap *soap = soap_new1(flag1 | flag2 | ... | flagn);
5948  ...
5949  soap_destroy(soap); // delete objects
5950  soap_end(soap); // delete other data and temp data
5951  soap_free(soap); // free context
5952 ~~~
5953 
5954 and with `soap_init1()` for stack-allocated contexts:
5955 
5956 ~~~{.cpp}
5957  struct soap soap;
5958  soap_init1(&soap, flag1 | flag2 | ... | flagn);
5959  ...
5960  soap_destroy(&soap); // delete objects
5961  soap_end(&soap); // delete other data and temp data
5962  soap_done(&soap); // clear context
5963 ~~~
5964 
5965 where `flag1`, `flag2`, ..., `flagn` is one of:
5966 
5967 - `SOAP_C_UTFSTRING`: enables all `std::string` and `char*` strings to
5968  contain UTF-8 content. This option is recommended.
5969 
5970 - `SOAP_C_NILSTRING`: treat empty strings as if they were NULL pointers, i.e.
5971  omits elements and attributes when empty.
5972 
5973 - `SOAP_XML_STRICT`: strictly validates XML while deserializing. Should not be
5974  used together with SOAP 1.1/1.2 encoding style of messaging. Use
5975  <b>`soapcpp2 -s`</b> option <b>`-s`</b> to hard code `SOAP_XML_STRICT` in the
5976  generated serializers. Not recommended with SOAP 1.1/1.2 encoding style
5977  messaging.
5978 
5979 - `SOAP_XML_INDENT`: produces indented XML.
5980 
5981 - `SOAP_XML_CANONICAL`: c14n canonocalization, removes unused `xmlns` bindings
5982  and adds them to appropriate places by applying c14n normalization rules.
5983  Should not be used together with SOAP 1.1/1.2 encoding style messaging.
5984 
5985 - `SOAP_XML_TREE`: write tree XML without id-ref, while pruning data structure
5986  cycles to prevent nontermination of the serializer for cyclic structures.
5987 
5988 - `SOAP_XML_GRAPH`: write graph (digraph and cyclic graphs with shared pointers
5989  to objects) using id-ref attributes. That is, XML with SOAP multi-ref
5990  encoded id-ref elements. This is a structure-preserving serialization format,
5991  because co-referenced data and also cyclic relations are accurately represented.
5992 
5993 - `SOAP_XML_DEFAULTNS`: uses xmlns default namespace declarations, assuming
5994  that the schema attribute form is "qualified" by default (be warned if it is
5995  not, since attributes in the null namespace will get bound to namespaces!).
5996 
5997 - `SOAP_XML_NIL`: emit empty element with <i>`xsi:nil`</i> for all NULL pointers
5998  serialized.
5999 
6000 - `SOAP_XML_IGNORENS`: the XML parser ignores XML namespaces, i.e. element and
6001  attribute tag names match independent of their namespace.
6002 
6003 - `SOAP_XML_NOTYPE`: removes all <i>`xsi:type`</i> attribuation. This option is usually
6004  not needed unless the receiver rejects all <i>`xsi:type`</i> attributes. This option
6005  may affect the quality of the deserializer, which relies on <i>`xsi:type`</i>
6006  attributes to distinguish base class instances from derived class instances
6007  transported in the XML payloads.
6008 
6009 - `SOAP_IO_CHUNK`: to enable HTTP chunked transfers.
6010 
6011 - `SOAP_IO_STORE`: full buffering of outbound messages.
6012 
6013 - `SOAP_ENC_ZLIB`: compress messages, requires compiling with option <b>`-DWITH_GZIP`</b> and
6014  linking with zlib using option <b>`-lz`</b>.
6015 
6016 - `SOAP_ENC_MIME`: enable MIME attachments, see
6017  [DIME/MIME/MTOM attachment binary types](#toxsd10-3).
6018 
6019 - `SOAP_ENC_MTOM`: enable MTOM attachments, see
6020  [DIME/MIME/MTOM attachment binary types](#toxsd10-3).
6021 
6022 @note C++ Web service proxy and service classes have their own `soap` context, either
6023 as a base class (with <b>`soapcpp2 -i`</b> option <b>`-i`</b>) or as a pointer member `soap` that points to
6024 a context (with <b>`soapcpp2 -j`</b> option <b>`-j`</b>). These contexts are allocated when the proxy or
6025 service is instantiated with context flags that are passed to the constructor.
6026 
6027 🔝 [Back to table of contents](#)
6028 
6029 Context parameter settings {#params}
6030 ==========================
6031 
6032 After allocation and initializtion of a `soap` context, several context
6033 parameters can be set (some parameters may require 2.8.31 or greater):
6034 
6035 - `unsigned int soap::maxlevel` is the maximum XML nesting depth levels that
6036  the parser permits. Default initialized to `SOAP_MAXLEVEL` (10000), which is
6037  a redefinable macro in <i>`gsoap/stdsoap2.h`</i>. Set `soap::maxlevel` to a
6038  lower value to restrict XML parsing nesting depth.
6039 
6040 - `long soap::maxlength` is the maximum string content length if not already
6041  constrained by an XML schema validation `maxLength` constraint. Zero means
6042  unlimited string lengths are permitted (unless restricted by XML schema
6043  `maxLength`). Default initialized to `SOAP_MAXLENGTH` (0), which is a
6044  redefinable macro in <i>`gsoap/stdsoap2.h`</i>. Set `soap::maxlength` to a
6045  positive value to restrict the number of (wide) characters in strings parsed,
6046  restrict hexBinary byte length, and restrict base64Binary byte length.
6047 
6048 - `size_t soap::maxoccurs` is the maximum number of array or container elements
6049  permitted by the parser. Must be greater than zero (0). Default initialized
6050  to `SOAP_MAXOCCURS` (100000), which is a redefinable macro in
6051  <i>`gsoap/stdsoap2.h`</i>. Set `soap::maxoccurs` to a positive value to
6052  restrict the number of array and container elements that can be parsed.
6053 
6054 - `soap::version` is the SOAP version used, with 0 for non-SOAP, 1 for SOAP1.1,
6055  and 2 for SOAP1.2. This value is normally set by web service operations, and
6056  is otherwise 0 (non-SOAP). Use `soap_set_version(struct soap*, short)` to
6057  set the value. This controls XML namespaces and SOAP id-ref serialization
6058  when applicable with an encodingStyle (see below).
6059 
6060 - `const char *soap::encodingStyle` is a string that is used with SOAP
6061  encoding, normally NULL for non-SOAP XML. Set this string to "" (empty
6062  string) to enable SOAP encoding style, which supports id-ref graph
6063  serialization (see also the `SOAP_XML_GRAPH` [context flag](#flags)).
6064 
6065 - `int soap::recvfd` is the file descriptor to read and parse source data from.
6066  Default initialized to 0 (stdin). See also [input and output](#io).
6067 
6068 - `int soap::sendfd` is the file descriptor to write data to. Default
6069  initialized to 1 (stdout). See also [input and output](#io).
6070 
6071 - `const char *is` for C: string to read and parse source data from, overriding
6072  the `recvfd` source. Normally NULL. This value must be reset to NULL or
6073  the parser will continue to read from this string content until the NUL
6074  character. See also [input and output](#io).
6075 
6076 - `std::istream *is` for C++: an input stream to read and parse source data
6077  from, overriding the `recvfd` source. Normally NULL. This value must be
6078  reset to NULL or the parser will continue to read from this stream until EOF.
6079  See also [input and output](#io).
6080 
6081 - `const char **os` for C: points to a string (a `const char *`) that will be
6082  set to point to the string output. Normally NULL. This value must be reset
6083  to NULL or the next output will result in reassigning the pointer to point to
6084  the next string that is output. The strings are automatically deallocated by
6085  `soap_end(soap)`. See also [input and output](#io).
6086 
6087 - `std::ostream *os` for C++: an output stream to write output to. Normally
6088  NULL. This value must be reste to NULL or the next output will be send to
6089  this stream. See also [input and output](#io).
6090 
6091 🔝 [Back to table of contents](#)
6092 
6093 Error handling and reporting {#errors}
6094 ============================
6095 
6096 The gSOAP API functions return `SOAP_OK` (zero) or a non-zero error code. The
6097 error code is stored in `int soap::error` of the current `soap` context.
6098 Error messages can be displayed with:
6099 
6100 - `void soap_stream_fault(struct soap*, std::ostream &os)` for C++ only, prints
6101  the error message to an output stream.
6102 
6103 - `void soap_print_fault(struct soap*, FILE *fd)` prints the error message to a
6104  FILE descriptor.
6105 
6106 - `void soap_sprint_fault(struct soap*, char *buf, size_t len)` saves the error
6107  message to a fixed-size buffer allocated with a maximum length.
6108 
6109 - `void soap_print_fault_location(struct soap*, FILE *fd)` prints the location
6110  and part of the XML where the parser encountered an error.
6111 
6112 C++ exceptions are never raised by the engine or serializers, even when data is
6113 allocated.
6114 
6115 A `SOAP_EOM` error code is returned when memory was exhausted during
6116 processing of input and/or output of data.
6117 
6118 An EOF (`SOAP_EOF` or -1) error code is returned when the parser has hit EOF
6119 but expected more input, or when socket communications timed out. In addition
6120 to the `SOAP_EOF` error, the `int soap::errnum` of the `soap` context is
6121 set to the `errno` value of the operation that failed. For timeouts, the
6122 `soap::ernum` value is always 0 instead of an `errno` error code.
6123 
6124 Use `soap_xml_error_check(soap->error)` to check for XML errors. This returns
6125 true (non-zero) when a parsing and validation error has occurred.
6126 
6127 For example:
6128 
6129 ~~~{.cpp}
6130  #include <sstream>
6131 
6132  struct soap *soap = soap_new1(SOAP_XML_INDENT | SOAP_XML_STRICT | SOAP_XML_TREE);
6133  struct ns__record person;
6134  std::stringstream ss;
6135  ss.str("..."); // XML to parse
6136  soap->is = &ss;
6137  if (soap_read__ns__record(soap, &person))
6138  {
6139  if (soap_xml_error_check(soap->error))
6140  std::cerr << "XML parsing error!" << std::endl;
6141  else
6142  soap_stream_fault(soap, std::cerr);
6143  }
6144  else
6145  {
6146  ... // all OK, use person record
6147  }
6148  soap_destroy(soap); // delete objects
6149  soap_end(soap); // delete other data and temp data
6150  soap_free(soap); // free context
6151 ~~~
6152 
6153 When deploying your application on UNIX and Linux systems, UNIX signal handlers
6154 should be added to your code handle signals, in particular `SIGPIPE`:
6155 
6156 ~~~{.cpp}
6157  signal(SIGPIPE, sigpipe_handler);
6158 ~~~
6159 
6160 where the `sigpipe_handler` is a function:
6161 
6162 ~~~{.cpp}
6163  void sigpipe_handler(int x) { }
6164 ~~~
6165 
6166 Other UNIX signals may have to be handled as well.
6167 
6168 The engine is designed for easy memory cleanup after being interrupted. Use
6169 `soap_destroy(soap)` and `soap_end(soap)`, after which the `soap` context can
6170 be reused.
6171 
6172 🔝 [Back to table of contents](#)
6173 
6174 Features and limitations {#features}
6175 ========================
6176 
6177 In general, to use the generated code:
6178 
6179 - Make sure to `#include "soapH.h"` in your code and also define a namespace
6180  table or `#include "ns.nsmap"` with the generated table, where `ns` is the
6181  namespace prefix for services.
6182 
6183 - Use <b>`soapcpp2 -j`</b> option <b>`-j`</b> (C++ only) to generate C++ proxy and service objects.
6184  The auto-generated files include documented inferfaces. Compile with
6185  <i>`soapC.cpp`</i> and link with <b>`-lgsoap++`</b>, or alternatively compile
6186  <i>`gsoap/stdsoap2.cpp`</i>.
6187 
6188 - Without <b>`soapcpp2 -j`</b> option <b>`-j`</b>: client-side uses the auto-generated
6189  <i>`soapClient.cpp`</i> and <i>`soapC.cpp`</i> (or C versions of those).
6190  Compile and link with <b>`-lgsoap++`</b> (<b>`-lgsoap`</b> for C), or
6191  alternatively compile <i>`gsoap/stdsoap2.cpp`</i> (<i>`gsoap/stdsoap2.c`</i>
6192  for C).
6193 
6194 - Without <b>`soapcpp2 -j`</b> option <b>`-j`</b>: server-side uses the
6195  auto-generated <i>`soapServer.cpp`</i> and <i>`soapC.cpp`</i> (or C versions
6196  of those). Compile and link with <b>`-lgsoap++`</b> (<b>`-lgsoap`</b> for
6197  C), or alternatively compile <i>`gsoap/stdsoap2.cpp`</i> (<i>`stdsoap2.c`</i>
6198  for C).
6199 
6200 - Use `soap_new()` or `soap_new1(int flags)` to allocate and initialize a
6201  heap-allocated `soap` context with or without flags. Delete this `soap` context with
6202  `soap_free(struct soap*)`, but only after `soap_destroy(struct soap*)` and
6203  `soap_end(struct soap*)`.
6204 
6205 - Use `soap_init(struct *soap)` or `soap_init1(struct soap*, int flags)` to
6206  initialize a stack-allocated `soap` context with or without flags. End the use of
6207  this context with `soap_done(struct soap*)`, but only after
6208  `soap_destroy(struct soap*)` and `soap_end(struct soap*)`.
6209 
6210 Additional notes with respect to the wsdl2h and soapcpp2 tools:
6211 
6212 - Nested classes, structs, and unions in a interface header file are unnested
6213  by soapcpp2.
6214 
6215 - Use `#import "file.h"` instead of `#include` to import other header files in
6216  a interface header file for soapcpp2. The `#include`, `#define`, and
6217  `#pragma` are accepted by soapcpp2, but are moved to the very start of the
6218  generated code for the C/C++ compiler to include before all generated
6219  definitions. Often it is useful to add an `#include` with a
6220  [volatile type](#toxsd9-2) that includes the actual type declaration, and to
6221  ensure transient types are declared when these are used in a data binding
6222  interface declared in a interface header file for soapcpp2.
6223 
6224 - To remove any SOAP-specific bindings, use <b>`soapcpp2 -0`</b> option <b>`-0`</b>.
6225 
6226 - A interface header file for soapcpp2 should not include any code statements,
6227  only data type declarations. This includes constructor initialization lists
6228  that are not permitted. Use member initializations instead.
6229 
6230 - C++ namespaces are supported. Use <b>`wsdl2h -qname`</b> option
6231  <b>`-qname`</b> to add C++ namespace `name`. Or add a `namespace name { ... }`
6232  to the header file, but the `{ ... }` must cover the entire
6233  header file content from begin to end.
6234 
6235 - Optional XML DOM support can be used to store mixed content or literal XML
6236  content. Otherwise, mixed content may be lost. Use <b>`wsdl2h -d`</b>
6237  option <b>`-d`</b> for XML DOM support and compile and link with
6238  <i>`gsoap/dom.c`</i> or <i>`gsoap/dom.cpp`</i>. For details,
6239  see [XML DOM and XPath](http://www.genivia.com/doc/dom/html).
6240 
6241 🔝 [Back to table of contents](#)
6242 
6243 Removing SOAP namespaces from XML payloads {#nsmap}
6244 ==========================================
6245 
6246 The soapcpp2 tool generates a <i>`.nsmap`</i> file that includes two bindings for SOAP
6247 namespaces. We can remove all SOAP namespaces (and SOAP processing logic) with
6248 <b>`soapcpp2 -0`</b> option <b>`-0`</b> or by simply setting the two entries to NULL:
6249 
6250 ~~~{.cpp}
6251  struct Namespace namespaces[] =
6252  {
6253  {"SOAP-ENV", NULL, NULL, NULL},
6254  {"SOAP-ENC", NULL, NULL, NULL},
6255  ...
6256  };
6257 ~~~
6258 
6259 Once the <i>`.nsmap`</i> is generated, you can copy-paste the content into your
6260 project code. However, if we rerun wsdl2h on updated WSDL/XSD files or
6261 <i>`typemap.dat`</i> declarations then we need to use the updated table.
6262 
6263 In cases that no XML namespaces are used at all, for example with
6264 [XML-RPC](http://www.genivia.com/doc/xml-rpc-json/html), you may use an empty
6265 namespace table:
6266 
6267 ~~~{.cpp}
6268  struct Namespace namespaces[] = {{NULL,NULL,NULL,NULL}};
6269 ~~~
6270 
6271 However, beware that any built-in xsi attributes that are rendered will lack
6272 the proper namespace binding. At least we suggest to use `SOAP_XML_NOTYPE` for
6273 this reason.
6274 
6275 🔝 [Back to table of contents](#)
6276 
6277 Examples {#examples}
6278 ========
6279 
6280 Select the project files below to peruse the source code examples.
6281 
6282 🔝 [Back to table of contents](#)
6283 
6284 Source files
6285 ------------
6286 
6287 - <i>`address.xsd`</i> Address book schema
6288 - <i>`address.cpp`</i> Address book app (reads/writes address.xml file)
6289 - <i>`addresstypemap.dat`</i> Schema namespace prefix name preference for wsdl2h
6290 - <i>`graph.h`</i> Graph data binding (tree, digraph, cyclic graph)
6291 - <i>`graph.cpp`</i> Test graph serialization as tree, digraph, and cyclic
6292 
6293 🔝 [Back to table of contents](#)
6294 
6295 Generated files
6296 ---------------
6297 
6298 - <i>`address.h`</i> data binding interface generated from address.xsd
6299 - <i>`addressStub.h`</i> C++ data binding definitions
6300 - <i>`addressH.h`</i> Serializers
6301 - <i>`addressC.cpp`</i> Serializers
6302 - <i>`address.xml`</i> Address book data generated by address app
6303 - <i>`graphStub.h`</i> C++ data binding definitions
6304 - <i>`graphH.h`</i> Serializers
6305 - <i>`graphC.cpp`</i> Serializers
6306 - <i>`g.xsd`</i> XSD schema with <i>`g:Graph`</i> complexType
6307 - <i>`g.nsmap`</i> xmlns bindings namespace mapping table
6308 
6309 🔝 [Back to table of contents](#)
6310 
6311 Build steps
6312 -----------
6313 
6314 Building the AddressBook example:
6315 
6316  wsdl2h -g -taddresstypemap.dat address.xsd
6317  soapcpp2 -0 -C -S -paddress -I../../import address.h
6318  c++ -I../.. address.cpp addressC.cpp -o address -lgsoap++
6319 
6320 Using <b>`wsdl2h -g -taddresstypemap.dat`</b> option <b>`-g`</b> produces
6321 bindings for global (root) elements in addition to types and option
6322 <b>`-taddresstypemap.dat`</b> specifies a mapping file, see further below.
6323 
6324 In this case the root element <i>`a:address-book`</i> is bound to `_a__address_book`.
6325 The complexType <i>`a:address`</i> is bound to class `a__address`, which is also the
6326 type of `_a__address_book`. This option is not required, but allows you to use
6327 global element tag names when referring to their serializers, instead of their
6328 type name. Using <b>`soapcpp2 -0 -C -S -paddress`</b> option <b>`-0`</b> removes the
6329 SOAP protocol and the combination of the two options <b>`-C`</b> and
6330 <b>`-S`</b> removes client and server code generation (using option <b>`-C`</b>
6331 alone generates client code and using option <b>`-S`</b> alone generates server
6332 code). Option <b>`-paddress`</b> renames the output <i>`soap`</i>-prefixed files to
6333 <i>`address`</i>-prefixed files.
6334 
6335 See the <i>`address.cpp`</i> implementation and [related pages](pages.html).
6336 
6337 The <i>`addresstypemap.dat`</i> file specifies the XML namespace prefix for the
6338 bindings:
6339 
6340  # Bind the address book schema namespace to prefix 'a'
6341 
6342  a = "urn:address-book-example"
6343 
6344  # By default the xsd:dateTime schema type is translated to time_t
6345  # To map xsd:dateTime to struct tm, enable the following line:
6346 
6347  # xsd__dateTime = #import "../../custom/struct_tm.h"
6348 
6349  # ... and compile/link with custom/struct_tm.c
6350 
6351 The DOB field is a <i>`xsd:dateTime`</i>, which is bound to `time_t` by default. To
6352 change this to `struct tm`, enable the import of the `xsd__dateTime` custom
6353 serializer by uncommenting the definition of `xsd__dateTime` in
6354 <i>`addresstypemap.dat`</i>. Then change `soap_dateTime2s` to `soap_xsd__dateTime2s`
6355 in the code.
6356 
6357 Building the graph serialization example:
6358 
6359  soapcpp2 -C -S -pgraph -I../../import graph.h
6360  c++ -I../.. graph.cpp graphC.cpp -o graph -lgsoap++
6361 
6362 To compile without using the <b>`-lgsoap++`</b> library: simply compile
6363 <i>`stdsoap2.cpp`</i> together with the above.
6364 
6365 🔝 [Back to table of contents](#)
6366 
6367 Usage
6368 -----
6369 
6370 To execute the AddressBook example:
6371 
6372  ./address
6373 
6374 To execute the Graph serialization example:
6375 
6376  ./graph
6377