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Data Bindings

 
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1 
2 XML Data Bindings {#mainpage}
3 =================
4 
5 [TOC]
6 
7 Introduction {#intro}
8 ============
9 
10 This is a detailed overview of the gSOAP XML data bindings concepts and
11 implementation. At the end of this document two examples are given to
12 illustrate the application of data bindings.
13 
14 The first simple example `address.cpp` shows how to use wsdl2h to bind an XML
15 schema to C++. The C++ application reads and writes an XML file into and from
16 a C++ "address book" data structure. The C++ data structure is an STL vector
17 of address objects.
18 
19 The second example `graph.cpp` shows how XML is serialized as a tree, digraph,
20 and cyclic graph. The digraph and cyclic graph serialization rules are similar
21 to SOAP 1.1/1.2 encoded multi-ref elements with id-ref attributes to link
22 elements through IDREF XML references, creating a an XML graph with pointers to
23 XML nodes.
24 
25 These examples demonstrate XML data bindings only for relatively simple data
26 structures and types. The gSOAP tools support more than just these type of
27 structures, which we will explain in the next sections. Support for XML schema
28 components is practically unlimited. The wsdl2h tool maps schemas to C and C++
29 using built-in intuitive mapping rules, while allowing the mappings to be
30 customized using a `typemap.dat` file with mapping instructions for wsdl2h.
31 
32 The information in this document is applicable to gSOAP 2.8.26 and higher, which
33 supports C++11 features. However, C++11 is not required to use this material
34 and follow the example, unless we need smart pointers and scoped enumerations.
35 While most of the examples in this document are given in C++, the concepts also
36 apply to C with the exception of containers, smart pointers, classes and their
37 methods. None of these exceptions limit the use of the gSOAP tools for C in any
38 way.
39 
40 The data binding concepts described in this document were first envisioned in
41 1999 by Prof. van Engelen at the Florida State University (the project was
42 named "stub/skeleton compiler"). The first articles on gSOAP appeared in 2002.
43 The principle of mapping XSD components to C/C++ types and vice versa is now
44 widely adopted in systems and programming languages, including Java web
45 services and by C# WCF.
46 
47 
48 Mapping WSDL and XML schemas to C/C++ {#tocpp}
49 =====================================
50 
51 To convert WSDL and XML schemas (XSD files) to code, we first use the wsdl2h
52 command to generate the data binding interface code that is saved to a special
53 gSOAP header file:
54 
55  wsdl2h [options] -o file.h ... XSD and WSDL files ...
56 
57 This command converts WSDL and XSD files to C++ (or pure C with wsdl2h option
58 `-c`) and saves a data binding interface file `file.h` that uses familar C/C++
59 syntax extended with `gsoap` directives and includes notational conventions
60 to declare C/C++ types and functions that are associated with these bindings.
61 
62 The WSDL 1.1/2.0, SOAP 1.1/1.2, and XSD 1.0/1.1 standards are supported by the
63 gSOAP tools. In addition, the most popular WS specifications are also
64 supported, including WS-Addressing, WS-ReliableMessaging, WS-Discovery,
65 WS-Security, WS-Policy, WS-SecurityPolicy, and WS-SecureConversation.
66 
67 This document focusses on XML data bindings and mapping C/C++ to XML 1.0/1.1
68 and XSD 1.0/1.1. This covers all of the following standard XSD components with
69 their optional `[ attributes ]` properties:
70 
71  schema [targetNamespace, version, elementFormDefault,
72  attributeFormDefault, defaultAttributes]
73  attribute [name, ref, type, use, default, fixed, form,
74  targetNamespace, wsdl:arrayType]
75  element [name, ref, type, default, fixed, form, nillable, abstract,
76  substitutionGroup, minOccurs, maxOccurs, targetNamespace]
77  simpleType [name]
78  complexType [name, abstract, mixed, defaultAttributesApply]
79  all
80  choice [minOccurs, maxOccurs]
81  sequence [minOccurs, maxOccurs]
82  group [name, ref, minOccurs, maxOccurs]
83  attributeGroup [name, ref]
84  any [minOccurs, maxOccurs]
85  anyAttribute
86 
87 And also the following standard XSD components:
88 
89  import imports a schema into the importing schema for referencing
90  include include schema component definitions into a schema
91  override override by replacing schema component definitions
92  redefine extend or restrict schema component definitions
93  annotation annotates a component
94 
95 The XSD facets and their mappings to C/C++ are:
96 
97  enumeration maps to enum
98  simpleContent maps to class/struct wrapper with __item member
99  complexContent maps to class/struct
100  list maps to enum* bitmask (enum* enumerates up to 64 bit masks)
101  extension through inheritance
102  restriction partly through inheritance and redeclaration
103  length restricts content length
104  minLength restricts content length
105  maxLength restricts content length
106  minInclusive restricts numerical value range
107  maxInclusive restricts numerical value range
108  minExclusive restricts numerical value range
109  maxExclusive restricts numerical value range
110  precision maps to float/double but constraint is not validated
111  scale maps to float/double but constraint is not validated
112  totalDigits maps to float/double but constraint is not validated
113  fractionDigits maps to float/double but constraint is not validated
114  pattern must define soap::fsvalidate callback to validate patterns
115  union maps to string of values
116 
117 All primitive XSD types are supported, including but not limited to the
118 following XSD types:
119 
120  anyType maps to _XML string with literal XML content (or DOM with wsdl2h option -d)
121  anyURI maps to string
122  string maps to string (char*/wchar_t*/std::string/std::wstring)
123  boolean maps to bool (C++) or enum xsd__boolean (C)
124  byte maps to char (int8_t)
125  short maps to short (int16_t)
126  int maps to int (int32_t)
127  long maps to LONG64 (long long and int64_t)
128  unsignedByte maps to unsigned char (uint8_t)
129  unsignedShort maps to unsigned short (uint16_t)
130  unsignedInt maps to unsigned int (uint32_t)
131  unsignedLong maps to ULONG64 (unsigned long long and uint64_t)
132  float maps to float
133  double maps to double
134  integer maps to string or #import "custom/int128.h"
135  decimal maps to string or #import "custom/long_double.h"
136  precisionDecimal maps to string
137  duration maps to string or #import "custom/duration.h"
138  dateTime maps to time_t or #import "custom/struct_tm.h"
139  time maps to string or #import "custom/long_time.h"
140  date maps to string or #import "custom/struct_tm_date.h"
141  hexBinary maps to class/struct xsd__hexBinary
142  base64Bianry maps to class/struct xsd__base64Binary
143  QName maps to _QName (URI normalization rules are applied)
144 
145 All other primitive XSD types not listed above are mapped to strings, by
146 generating a typedef. For example, xsd:token is bound to a C++ or C string,
147 which associates a value space to the type with the appropriate XSD type name
148 used by the soapcpp2-generated serializers:
149 
150  typedef std::string xsd__token; // C++
151  typedef char *xsd__token; // C (wsdl2h option -c)
152 
153 It is possible to remap types by adding the appropriate mapping rules to
154 `typemap.dat` as we will explain in more detail in the next section.
155 
156 Imported custom serializers are intended to extend the C/C++ type bindings when
157 the default binding to string is not satisfactory to your taste and if the
158 target platform supports these C/C++ types. To add custom serializers to
159 `typemap.dat` for wsdl2h, see [Adding custom serializers](#custom) below.
160 
161 
162 Using typemap.dat to customize data bindings {#typemap}
163 ============================================
164 
165 We use a `typemap.dat` file to redefine namespace prefixes and to customize
166 type bindings for the the generated header files produced by the wsdl2h tool.
167 The `typemap.dat` is the default file processed by wsdl2h. Use wsdl2h option
168 `-t` to specify a different file.
169 
170 Declarations in `typemap.dat` can be broken up over multiple lines by
171 continuing on the next line by ending each line to be continued with a
172 backslash `\`. The limit is 4095 characters per line, whether the line is
173 broken up or not.
174 
175 
176 XML namespace bindings {#typemap1}
177 ----------------------
178 
179 The wsdl2h tool generates C/C++ type declarations that use `ns1`, `ns2`, etc.
180 as schema-binding URI prefixes. These default prefixes are generated somewhat
181 arbitrarily for each schema targetNamespace URI, meaning that their ordering
182 may change depending on the WSDL and XSD order of processing with wsdl2h.
183 
184 Therefore, it is **strongly recommended** to declare your own prefix for each
185 schema URI in `typemap.dat` to reduce maintaince effort of your code. This
186 is more robust when anticipating possible changes of the schema(s) and/or the
187 binding URI(s) and/or the tooling algorithms.
188 
189 The first and foremost important thing to do is to define prefix-URI bindings
190 for our C/C++ code by adding the following line(s) to our `typemap.dat` or make
191 a copy of this file and add the line(s) that bind our choice of prefix name to
192 each URI:
193 
194  prefix = "URI"
195 
196 For example:
197 
198  g = "urn:graph"
199 
200 This produces `g__name` C/C++ type names that are bound to the "urn:graph"
201 schema by association of `g` to the generated C/C++ types.
202 
203 This means that `<g:name xmlns:g="urn:graph">` is parsed as an instance of a
204 `g__name` C/C++ type. Also `<x:name xmlns:x="urn:graph">` parses as an instance
205 of `g__name`, because the prefix `x` has the same URI value `urn:graph`.
206 Prefixes in XML have local scopes (like variables in a block).
207 
208 The first run of wsdl2h will reveal the URIs, so you do not need to search
209 WSDLs and XSD files for all of the target namespaces. Just copy them from the
210 generated header file after the first run into `typemap.dat` for editing.
211 
212 
213 XSD type bindings {#typemap2}
214 -----------------
215 
216 Custom C/C++ type bindings can be declared in `typemap.dat` to associate C/C++
217 types with specific schema types. These type bindings have four parts:
218 
219  prefix__type = declaration | use | ptruse
220 
221 where
222 
223 - `prefix__type` is the schema type to be customized (the `prefix__type` name
224  uses the common double underscore naming convention);
225 - `declaration` declares the C/C++ type in the wsdl2h-generated header file.
226  This part can be empty if no explicit declaration is needed;
227 - `use` is an optional part that specifies how the C/C++ type is used in the
228  code. When omitted, it is the same as `prefix__type`;
229 - `ptruse` is an optional part that specifies how the type is used as a
230  pointer type. By default it is the `use` type name with a `*` or C++11
231  `std::shared_ptr<>` when enabled (see further below).
232 
233 For example, to map xsd:duration to a `long long` (`LONG64`) type that holds
234 millisecond duration values, we can use the custom serializer declared in
235 `custom/duration.h` by adding the following line to `typemap.dat`:
236 
237  xsd__duration = #import "custom/duration.h"
238 
239 Here, we omitted the second field, because `xsd__duration` is the name that
240 wsdl2h uses to identify and use this type for our code. The third field is
241 omitted to let wsdl2h use `xsd__duration *` for pointers or
242 `std::shared_ptr<xsd__duration>` if smart pointers are enabled.
243 
244 To map xsd:string to `wchar_t*` wide strings:
245 
246  xsd__string = | wchar_t* | wchar_t*
247 
248 Note that the first field is empty, because `wchar_t` is a C type and does not
249 need to be declared. A `ptruse` field is given so that we do not end up
250 generating the wrong pointer types, such as `wchar_t**` and
251 `std::shared_ptr<wchar_t>`.
252 
253 When the auto-generated declaration should be preserved but the `use` or
254 `ptruse` fields replaced, then we use an ellipsis for the declaration part:
255 
256  prefix__type = ... | use | ptruse
257 
258 This is useful to map schema polymorphic types to C types for example, where we
259 need to be able to both handle a base type and its extensions as per schema
260 extensibility. Say we have a base type called ns:base that is extended, then we
261 can remap this to a C type that permits referening the extended types via a
262 `void*` as follows:
263 
264  ns__base = ... | int __type_base; void*
265 
266 such that `__type_base` and `void*` are used to (de)serialize any data type,
267 including base and its derived types.
268 
269 
270 Custom serializers for XSD types {#custom}
271 --------------------------------
272 
273 In the previous part we saw how a custom serializer is used to bind
274 xsd:duration to a `long long` (`LONG64` or `int64_t`) type to store millisecond
275 duration values:
276 
277  xsd__duration = #import "custom/duration.h"
278 
279 The `xsd__duration` type is an alias of `long long` (`LONG64` or `int64_t`).
280 
281 While wsdl2h will use this binding declared in `typemap.dat` automatically, you
282 will also need to compile `custom/duration.c`. Each custom serializer has a
283 header file and an implementation file written in C. You can compile these in
284 C++ (rename files to `.cpp` if needed).
285 
286 We will discuss the custom serializers that are available to you.
287 
288 ### xsd:integer {#custom-1}
289 
290 The wsdl2h tool maps xsd:integer to a string by default. To map xsd:integer to
291 the 128 bit big int type `__int128_t`:
292 
293  xsd__integer = #import "custom/int128.h"
294 
295 The `xsd__integer` type is an alias of `__int128_t`.
296 
297 @warning Beware that the xsd:integer value space of integers is in principle
298 unbounded and values can be of arbitrary length. A value range fault
299 `SOAP_TYPE` (value exceeds native representation) or `SOAP_LENGTH` (value
300 exceeds range bounds) will be thrown by the deserializer if the value is out of
301 range.
302 
303 Other XSD integer types that are restrictions of xsd:integer, are
304 xsd:nonNegativeInteger and xsd:nonPositiveInteger, which are further restricted
305 by xsd:positiveInteger and xsd:negativeInteger. To bind these types to
306 `__int128_t` we should also add the following definitions to `typemap.dat`:
307 
308  xsd__nonNegativeInteger = typedef xsd__integer xsd__nonNegativeInteger 0 : ;
309  xsd__nonPositiveInteger = typedef xsd__integer xsd__nonPositiveInteger : 0 ;
310  xsd__positiveInteger = typedef xsd__integer xsd__positiveInteger 1 : ;
311  xsd__negativeInteger = typedef xsd__integer xsd__negativeInteger : -1 ;
312 
313 @note If `__int128_t` 128 bit integers are not supported on your platform and if it
314 is certain that xsd:integer values are within 64 bit value bounds for your
315 application's use, then you can map this type to `LONG64`:
316 
317  xsd__integer = typedef LONG64 xsd__integer;
318 
319 @note Again, a value range fault `SOAP_TYPE` or `SOAP_LENGTH` will be thrown by
320 the deserializer if the value is out of range.
321 
322 @see Section [Numerical types](#toxsd5).
323 
324 ### xsd:decimal {#custom-2}
325 
326 The wsdl2h tool maps xsd:decimal to a string by default. To map xsd:decimal to
327 extended precision floating point:
328 
329  xsd__decimal = #import "custom/long_double.h" | long double
330 
331 By contrast to all other custom serializers, this serializer enables `long
332 double` natively without requiring a new binding name (`xsd__decimal` is NOT
333 defined).
334 
335 If your system supports `<quadmath.h>` quadruple precision floating point
336 `__float128`, you can map xsd:decimal to `xsd__decimal` that is an alias of
337 `__float128`:
338 
339  xsd__decimal = #import "custom/float128.h"
340 
341 @warning Beware that xsd:decimal is in principle a decimal value with arbitraty
342 lengths. A value range fault `SOAP_TYPE` will be thrown by the deserializer if
343 the value is out of range.
344 
345 In the XML payload the special values `INF`, `-INF`, `NaN` represent plus or
346 minus infinity and not-a-number, respectively.
347 
348 @see Section [Numerical types](#toxsd5).
349 
350 ### xsd:dateTime {#custom-3}
351 
352 The wsdl2h tool maps xsd:dateTime to `time_t` by default.
353 
354 The trouble with `time_t` is that it is limited to dates between 1970 and 2038
355 (until its decided by 2038 to widen the bit representation of `time_t`).
356 
357 For this reason `struct tm` should be used to represent wider date ranges. This
358 custom serializer avoids using date and time information in `time_t`. You get
359 the raw date and time information. You only lose the day of the week
360 information. It is always Sunday (`tm_wday=0`).
361 
362 To map xsd:dateTime to `xsd__dateTime` which is an alias of `struct tm`:
363 
364  xsd__dateTime = #import "custom/struct_tm.h"
365 
366 If the limited date range of `time_t` is not a problem but you want to increase
367 the time precision with fractional seconds, then we suggest to map xsd:dateTime
368 to `struct timeval`:
369 
370  xsd__dateTime = #import "custom/struct_timeval.h"
371 
372 If the limited date range of `time_t` is not a problem but you want to use the
373 C++11 time point type `std::chrono::system_clock::time_point` (which internally
374 uses `time_t`):
375 
376  xsd__dateTime = #import "custom/chrono_time_point.h"
377 
378 Again, we should make sure that the dates will not exceed the date range when
379 using the default `time_t` binding for xsd:dateTime or when binding
380 xsd:dateTime to `struct timeval` or to `std::chrono::system_clock::time_point`.
381 These are safe to use in applications that use xsd:dateTime to record date
382 stamps within a given window. Otherwise, we recommend the `struct tm` custom
383 serializer. You could even map xsd:dateTime to a plain string (use `char*` with
384 C and `std::string` with C++). For example:
385 
386  xsd__dateTime = | char*
387 
388 @see Section [Date and time types](#toxsd7).
389 
390 ### xsd:date {#custom-4}
391 
392 The wsdl2h tool maps xsd:date to a string by default. We can map xsd:date to
393 `struct tm`:
394 
395  xsd__date = #import "custom/struct_tm_date.h"
396 
397 The `xsd__date` type is an alias of `struct tm`. The serializer ignores the
398 time part and the deserializer only populates the date part of the struct,
399 setting the time to 00:00:00. There is no unreasonable limit on the date range
400 because the year field is stored as an integer (`int`).
401 
402 @see Section [Date and time types](#toxsd7).
403 
404 ### xsd:time {#custom-5}
405 
406 The wsdl2h tool maps xsd:time to a string by default. We can map xsd:time to
407 an `unsigned long long` (`ULONG64` or `uint64_t`) integer with microsecond time
408 precision:
409 
410  xsd__time = #import "custom/long_time.h"
411 
412 This type represents 00:00:00.000000 to 23:59:59.999999, from `0` to an upper
413 bound of `86399999999`. A microsecond resolution means that a 1 second
414 increment requires an increment of 1000000 in the integer value. The serializer
415 adds a UTC time zone.
416 
417 @see Section [Date and time types](#toxsd7).
418 
419 ### xsd:duration {#custom-6}
420 
421 The wsdl2h tool maps xsd:duration to a string by default, unless xsd:duration
422 is mapped to a `long long` (`LONG64` or `int64_t`) type with with millisecond
423 (ms) time duration precision:
424 
425  xsd__duration = #import "custom/duration.h"
426 
427 The `xsd__duration` type is a 64 bit signed integer that can represent
428 106,751,991,167 days forwards (positive) and backwards (negative) in time in
429 increments of 1 ms (1/1000 of a second).
430 
431 Rescaling of the duration value by may be needed when adding the duration value
432 to a `time_t` value, because `time_t` may or may not have a seconds resolution,
433 depending on the platform and possible changes to `time_t`.
434 
435 Rescaling is done automatically when you add a C++11 `std::chrono::nanoseconds`
436 value to a `std::chrono::system_clock::time_point` value. To use
437 `std::chrono::nanoseconds` as xsd:duration:
438 
439  xsd__duration = #import "custom/chrono_duration.h"
440 
441 This type can represent 384,307,168 days (2^63 nanoseconds) forwards and
442 backwards in time in increments of 1 ns (1/1,000,000,000 of a second).
443 
444 Certain observations with respect to receiving durations in years and months
445 apply to both of these serializer decoders for xsd:duration.
446 
447 @see Section [Time duration types](#toxsd8).
448 
449 
450 Class/struct member additions {#typemap3}
451 -----------------------------
452 
453 All generated classes and structs can be augmented with additional
454 members such as methods, constructors and destructors, and private members:
455 
456  prefix__type = $ member-declaration
457 
458 For example, we can add method declarations and private members to a class, say
459 `ns__record` as follows:
460 
461  ns__record = $ ns__record(const ns__record &); // copy constructor
462  ns__record = $ void print(); // a print method
463  ns__record = $ private: int status; // a private member
464 
465 Note that method declarations cannot include any code, because soapcpp2's input
466 permits only type declarations, not code.
467 
468 
469 Replacing XSD types by equivalent alternatives {#typemap4}
470 ----------------------------------------------
471 
472 Type replacements can be given to replace one type entirely with another given
473 type:
474 
475  prefix__type1 == prefix__type2
476 
477 This replaces all `prefix__type1` by `prefix__type2` in the wsdl2h output.
478 
479 @warning Do not agressively replace types, because this can cause XML
480 validation to fail when a value-type mismatch is encountered in the XML input.
481 Therefore, only replace similar types with other similar types that are wider
482 (e.g. `short` by `int` and `float` by `double`).
483 
484 
485 The built-in typemap.dat variables $CONTAINER and $POINTER {#typemap5}
486 ----------------------------------------------------------
487 
488 The `typemap.dat` `$CONTAINER` variable defines the container to emit in the
489 generated declarations, which is `std::vector` by default. For example, to emit
490 `std::list` as the container in the wsdl2h-generated declarations:
491 
492  $CONTAINER = std::list
493 
494 The `typemap.dat` `$POINTER` variable defines the smart pointer to emit in the
495 generated declarations, which replaces the use of `*` pointers. For example:
496 
497  $POINTER = std::shared_ptr
498 
499 Not all pointers in the generated output can be replaced by smart pointers.
500 Regular pointers are still used as union members and for pointers to arrays of
501 objects.
502 
503 @note The standard smart pointer `std::shared_ptr` is generally safe to use.
504 Other smart pointers such as `std::unique_ptr` and `std::auto_ptr` may cause
505 compile-time errors when classes have smart pointer members but no copy
506 constructor (a default copy constructor). A copy constructor is required for
507 non-shared smart pointer copying or swapping.
508 
509 Alternatives to `std::shared_ptr` of the form `NAMESPACE::shared_ptr` can be
510 assigned to `$POINTER` when the namespace `NAMESPACE` also implements
511 `NAMESPACE::make_shared` and when the shared pointer class provides `reset()`
512 and`get()` methods and the dereference operator. For example Boost
513 `boost::shared_ptr`:
514 
515  [
516  #include <boost/shared_ptr.hpp>
517  ]
518  $POINTER = boost::shared_ptr
519 
520 The user-defined content between `[` and `]` ensures that we include the Boost
521 header files that are needed to support `boost::shared_ptr` and
522 `boost::make_shared`.
523 
524 
525 User-defined content {#typemap6}
526 --------------------
527 
528 Any other content to be generated by wsdl2h can be included in `typemap.dat` by
529 enclosing it within brackets `[` and `]` anywhere in the `typemap.dat` file.
530 Each of the two brackets MUST appear at the start of a new line.
531 
532 For example, we can add an `#import "wsa5.h"` directive to the wsdl2h-generated
533 output as follows:
534 
535  [
536  #import "import/wsa5.h"
537  ]
538 
539 which emits the `#import "import/wsa5.h"` literally at the start of the
540 wsdl2h-generated header file.
541 
542 
543 Mapping C/C++ to XML schema {#toxsd}
544 ===========================
545 
546 The soapcpp2 command generates the data binding implementation code from a data
547 binding interface `file.h`:
548 
549  soapcpp2 [options] file.h
550 
551 where `file.h` is a gSOAP header file that declares the XML data binding
552 interface. The `file.h` is typically generated by wsdl2h, but we can also
553 declare one ourself. If so, we add gSOAP directives and declare in this file
554 all our C/C++ types we want to serialize in XML. We can also declare functions
555 that will be converted to service operations by soapcpp2.
556 
557 Global function declarations define service operations, which are of the form:
558 
559  int ns__name(arg1, arg2, ..., argn, result);
560 
561 where `arg1`, `arg2`, ..., `argn` are formal argument declarations of the input
562 and `result` is a formal argument for the output, which must be a pointer or
563 reference to the result object to be populated. More information can be found
564 in the gSOAP user guide.
565 
566 
567 Overview of serializable C/C++ types {#toxsd1}
568 ------------------------------------
569 
570 The following C/C++ types are supported by soapcpp2 and mapped to XSD types
571 and constructs. See the subsections below for more details or follow the links.
572 
573 ### List of Boolean types
574 
575  bool C++ bool
576  enum xsd__boolean C alternative bool
577 
578 @see Section [C++ bool and C alternative](#toxsd3).
579 
580 ### List of enumeration and bitmask types
581 
582  enum enumeration
583  enum class C++11 scoped enumeration (soapcpp2 -c++11)
584  enum* a bitmask that enumerates values 1, 2, 4, 8, ...
585  enum* class C++11 scoped enumeration bitmask (soapcpp2 -c++11)
586 
587 @see Section [Enumerations and bitmasks](#toxsd4).
588 
589 ### List of numerical types
590 
591  char byte
592  short 16 bit integer
593  int 32 bit integer
594  long 32 bit integer
595  LONG64 64 bit integer
596  xsd__integer 128 bit __int128_t integer, use #import "custom/int128.h"
597  long long same as LONG64
598  unsigned char unsigned byte
599  unsigned short unsigned 16 bit integer
600  unsigned int unsigned 32 bit integer
601  unsigned long unsigned 32 bit integer
602  ULONG64 unsigned 64 bit integer
603  unsigned long long same as ULONG64
604  int8_t same as char
605  int16_t same as short
606  int32_t same as int
607  int64_t same as LONG64
608  uint8_t same as unsigned char
609  uint16_t same as unsigned short
610  uint32_t same as unsigned int
611  uint64_t same as ULONG64
612  size_t transient type (not serializable)
613  float 32 bit float
614  double 64 bit float
615  long double extended precision float, use #import "custom/long_double.h"
616  xsd__decimal <quadmath.h> 128 bit __float128 quadruple precision float, use #import "custom/float128.h"
617  typedef declares a type name, with optional value range and string length bounds
618 
619 @see Section [Numerical types](#toxsd5).
620 
621 ### List of string types.
622 
623  char* string
624  wchar_t* wide string
625  std::string C++ string
626  std::wstring C++ wide string
627  char[N] fixed-size string, requires soapcpp2 option -b
628  _QName normalized QName content
629  _XML literal XML string content
630  typedef declares a type name, may restrict string length
631 
632 @see Section [String types](#toxsd6).
633 
634 ### List of date and time types
635 
636  time_t date and time point since epoch
637  struct tm date and time point, use #import "custom/struct_tm.h"
638  struct tm date point, use #import "custom/struct_tm_date.h"
639  struct timeval date and time point, use #import "custom/struct_timeval.h"
640  unsigned long long time point in microseconds, use #import "custom/long_time.h"
641  std::chrono::system_clock::time_point
642  date and time point, use #import "custom/chrono_time_point.h"
643 
644 @see Section [Date and time types](#toxsd7).
645 
646 ### List of time duration types
647 
648  long long duration in milliseconds, use #import "custom/duration.h"
649  std::chrono::nanoseconds duration in nanoseconds, use #import "custom/chrono_duration.h"
650 
651 @see Section [Time duration types](#toxsd8).
652 
653 ### List of classes and structs
654 
655  class C++ class with single inheritance only
656  struct C struct or C++ struct without inheritance
657  T* pointer to type T
658  T[N] fixed-size array of type T
659  std::shared_ptr<T> C++11 smart shared pointer
660  std::unique_ptr<T> C++11 smart pointer
661  std::auto_ptr<T> C++ smart pointer
662  std::deque<T> use #import "import/stldeque.h"
663  std::list<T> use #import "import/stllist.h"
664  std::vector<T> use #import "import/stlvector.h"
665  std::set<T> use #import "import/stlset.h"
666  template<T> class a container with begin(), end(), size(), clear(), and insert() methods
667  union requires a discriminant member
668  void* requires a __type member to indicate the type of object pointed to
669 
670 @see Section [Classes and structs](#toxsd9).
671 
672 ### List of special classes and structs
673 
674  Array single and multidimensional SOAP Arrays
675  xsd__hexBinary binary content
676  xsd__base64Binary binary content and optional MIME/MTOM attachments
677  Wrapper complexTypes with simpleContent
678 
679 @see Section [Special classes and structs](#toxsd10).
680 
681 
682 Colon notation versus name prefixing {#toxsd2}
683 ------------------------------------
684 
685 To bind C/C++ type names to XSD types, a simple form of name prefixing is used
686 by the gSOAP tools by prepending the XML namespace prefix to the C/C++ type
687 name with a pair of undescrores. This also ensures that name clashes cannot
688 occur when multiple WSDL and XSD files are converted to C/C++. Also, C++
689 namespaces are not sufficiently rich to capture XML schema namespaces
690 accurately, for example when class members are associated with schema elements
691 defined in another XML namespace and thus the XML namespace scope of the
692 member's name is relevant, not just its type.
693 
694 However, from a C/C++ centric point of view this can be cumbersome. Therefore,
695 colon notation is an alternative to physically augmenting C/C++ names with
696 prefixes.
697 
698 For example, the following class uses colon notation to bind the `record` class
699 to the `urn:types` schema:
700 
701  //gsoap ns schema namespace: urn:types
702  class ns:record // binding 'ns:' to a type name
703  {
704  public:
705  std::string name;
706  uint64_t SSN;
707  ns:record *spouse; // using 'ns:' with the type name
708  ns:record(); // using 'ns:' here too
709  ~ns:record(); // and here
710  };
711 
712 The colon notation is stripped away by soapcpp2 when generating the data
713 binding implementation code for our project. So the final code just uses
714 `record` to identify this class and its constructor/destructor.
715 
716 When using colon notation we have to be consistent and not use colon notation
717 mixed with prefixed forms. The name `ns:record` differs from `ns__record`,
718 because `ns:record` is compiled to an unqualified `record` name.
719 
720 
721 C++ Bool and C alternative {#toxsd3}
722 --------------------------
723 
724 The C++ `bool` type is bound to built-in XSD type xsd:boolean.
725 
726 The C alternative is to define an enumeration:
727 
728  enum xsd__boolean { false_, true_ };
729 
730 or by defining an enumeration in C with pseudo-scoped enumeration constants:
731 
732  enum xsd__boolean { xsd__boolean__false, xsd__boolean__true };
733 
734 The XML value space of these types is `false` and `true`, but also accepts `0`
735 and `1` as values.
736 
737 To prevent name clashes, `false_` and `true_` have an underscore which are
738 removed in the XML value space.
739 
740 
741 Enumerations and bitmasks {#toxsd4}
742 -------------------------
743 
744 Enumerations are mapped to XSD simpleType enumeration restrictions of
745 xsd:string, xsd:QName, and xsd:long.
746 
747 Consider for example:
748 
749  enum ns__Color { RED, WHITE, BLUE };
750 
751 which maps to a simpleType restriction of xsd:string in the soapcpp2-generated
752 schema:
753 
754  <simpleType name="Color">
755  <restriction base="xsd:string">
756  <enumeration value="RED"/>
757  <enumeration value="WHITE"/>
758  <enumeration value="BLUE"/>
759  </restriction>
760  </simpleType>
761 
762 Enumeration name constants can be pseudo-scoped to prevent name clashes,
763 because enumeration name constants have a global scope in C and C++:
764 
765  enum ns__Color { ns__Color__RED, ns__Color__WHITE, ns__Color__BLUE };
766 
767 We can also use C++11 scoped enumerations to prevent name clashes:
768 
769  enum class ns__Color : int { RED, WHITE, BLUE };
770 
771 Here, the enumeration class base type `: int` is optional. In place of `int`
772 in the example above, we can also use `int8_t`, `int16_t`, `int32_t`, or
773 `int64_t`.
774 
775 The XML value space of the enumertions defined above is `RED`, `WHITE`, and
776 `BLUE`.
777 
778 Prefix-qualified enumeration name constants are mapped to simpleType
779 restrictions of xsd:QName, for example:
780 
781  enum ns__types { xsd__int, xsd__float };
782 
783 which maps to a simpleType restriction of xsd:QName in the soapcpp2-generated
784 schema:
785 
786  <simpleType name="types">
787  <restriction base="xsd:QName">
788  <enumeration value="xsd:int"/>
789  <enumeration value="xsd:float"/>
790  </restriction>
791  </simpleType>
792 
793 Enumeration name constants can be pseudo-numeric as follows:
794 
795  enum ns__Primes { _3 = 3, _5 = 5, _7 = 7, _11 = 11 };
796 
797 which maps to a simpleType restriction of `xsd:long`:
798 
799  <simpleType name="Color">
800  <restriction base="xsd:long">
801  <enumeration value="3"/>
802  <enumeration value="5"/>
803  <enumeration value="7"/>
804  <enumeration value="11"/>
805  </restriction>
806  </simpleType>
807 
808 The XML value space of this type is `3`, `5`, `7`, and `11`.
809 
810 Besides (pseudo-) scoped enumerations, another way to prevent name clashes
811 accross enumerations is to start an enumeration name constant with one
812 underscore or followed it by any number of underscores, which makes it
813 unique. The leading and trailing underscores are removed in the XML value
814 space.
815 
816  enum ns__ABC { A, B, C };
817  enum ns__BA { B, A }; // BAD: B = 1 but B is already defined as 2
818  enum ns__BA_ { B_, A_ }; // OK
819 
820 The gSOAP soapcpp2 tool permits reusing enumeration name constants across
821 (non-scoped) enumerations as long as these values are assigned the same
822 constant. Therefore, the following is permitted:
823 
824  enum ns__Primes { _3 = 3, _5 = 5, _7 = 7, _11 = 11 };
825  enum ns__Throws { _1 = 1, _2 = 2, _3 = 3, _4 = 4, _5 = 5, _6 = 6 };
826 
827 A bitmask type is an `enum*` "product" enumeration with a geometric,
828 power-of-two sequence of values assigned to the enumeration constants:
829 
830  enum* ns__Options { SSL3, TLS10, TLS11, TLS12 };
831 
832 where the product enum assigns 1 to `SSL3`, 2 to `TLS10`, 4 to `TLS11`, and 8
833 to `TLS12`, which allows these enumeration constants to be used in composing
834 bitmasks with `|` (bitwise or) `&` (bitwise and), and `~` (bitwise not):
835 
836  enum ns__Options options = (enum ns__Options)(SSL3 | TLS10 | TLS11 | TLS12);
837  if (options & SSL3) // if SSL3 is an option, warn and remove from options
838  {
839  warning();
840  options &= ~SSL3;
841  }
842 
843 The bitmask type maps to a simpleType list restriction of xsd:string in the
844 soapcpp2-generated schema:
845 
846  <simpleType name="Options">
847  <list>
848  <restriction base="xsd:string">
849  <enumeration value="SSL3"/>
850  <enumeration value="TLS10"/>
851  <enumeration value="TLS11"/>
852  <enumeration value="TLS12"/>
853  </restriction>
854  </list>
855  </simpleType>
856 
857 The XML value space of this type consists of all 16 possible subsets of the
858 four values, represented by an XML string with space-separated values. For
859 example, the bitmask `TLS10 | TLS11 | TLS12` equals 14 and is represented in by
860 the XML string `TLS10 TLS11 TLS12`.
861 
862 We can also use C++11 scoped enumerations with bitmasks:
863 
864  enum* class ns__Options { SSL3, TLS10, TLS11, TLS12 };
865 
866 The base type of a scoped enumeration bitmask, when explicitly given, is
867 ignored. The base type is either `int` or `int64_t`, depending on the number
868 of constants enumerated in the bitmask.
869 
870 To convert `enum` name constants and bitmasks to a string, we use the
871 auto-generated function for enum `T`:
872 
873  const char *soap_T2s(struct soap*, enum T val)
874 
875 To convert a string to an `enum` constant or bitmask, we use the auto-generated
876 function
877 
878  int soap_s2T(struct soap*, const char *str, enum T *val)
879 
880 This function takes the name (or names, space-separated for bitmasks) of
881 the enumeration constant in a string `str`. Names should be given without the
882 pseudo-scope prefix and without trailing underscores. The function sets `val`
883 to the corresponding integer enum constant or to a bitmask. The function
884 returns `SOAP_OK` (zero) on success or an error if the string is not a valid
885 enumeration name.
886 
887 
888 Numerical types {#toxsd5}
889 ---------------
890 
891 Integer and floating point types are mapped to the equivalent built-in XSD
892 types with the same sign and bit width.
893 
894 The `size_t` type is transient (not serializable) because its width is platform
895 dependent. We recommend to use `uint64_t` instead.
896 
897 The XML value space of integer types are their decimal representations without
898 loss of precision.
899 
900 The XML value space of floating point types are their decimal representations.
901 The decimal representations are formatted with the printf format string "%.9G"
902 for floats and the printf format string "%.17lG" for double. To change the
903 format strings, we can assign new strings to the following `struct soap`
904 context members:
905 
906  soap.float_format = "%g";
907  soap.double_format = "%lg";
908  soap.long_double_format = "%Lg";
909 
910 Note that decimal representations may result in a loss of precision of the
911 least significant decimal. Therefore, the format strings that are used by
912 default are sufficiently precise to avoid loss, but this may result in long
913 decimal fractions in the XML value space.
914 
915 The `long double` extended floating point type requires a custom serializer:
916 
917  #import "custom/long_double.h"
918  ... use long double ...
919 
920 You can now use `long double`, which has a serializer that serializes this type
921 as `xsd:decimal`. Compile and link your code with `custom/long_double.c`.
922 
923 The value space of floating point values includes the special values `INF`,
924 `-INF`, and `NaN`. You can check a value for plus or minus infinity and
925 not-a-number as follows:
926 
927  soap_isinf(x) && x > 0 // is x INF?
928  soap_isinf(x) && x < 0 // is x -INF?
929  soap_isnan(x) // is x NaN?
930 
931 To assign these values, use:
932 
933  // x is float // x is double, long double, or __float128
934  x = FLT_PINFY; x = DBL_PINFTY;
935  x = FLT_NINFY; x = DBL_NINFTY;
936  x = FLT_NAN; x = DBL_NAN;
937 
938 If your system supports `__float128` then you can also use this 128 bit
939 floating point type with a custom serializer:
940 
941  #import "custom/float128.h"
942  ... use xsd__decimal ...
943 
944 Then use the `xsd__decimal` alias of `__float128`, which has a serializer. Do
945 not use `__float128` directly, which is transient (not serializable).
946 
947 To check for `INF`, `-INF`, and `NaN` of a `__float128` value use:
948 
949  isinfq(x) && x > 0 // is x INF?
950  isinfq(x) && x < 0 // is x -INF?
951  isnanq(x) // is x NaN?
952 
953 The range of a typedef-defined numerical type can be restricted using the range
954 `:` operator with inclusive lower and upper bounds. For example:
955 
956  typedef int ns__narrow -10 : 10;
957 
958 This maps to a simpleType restriction of xsd:int in the soapcpp2-generated
959 schema:
960 
961  <simpleType name="narrow">
962  <restriction base="xsd:int">
963  <minInclusive value="-10"/>
964  <maxInclusive value="10"/>
965  </restriction>
966  </simpleType>
967 
968 The lower and upper bound of a range are optional. When omitted, values are
969 not bound from below or from above, respectively.
970 
971 The range of a floating point typedef-defined type can be restricted within
972 floating point constant bounds.
973 
974 Also with a floating point typedef a printf format pattern can be given of the
975 form `"%[width][.precision]f"` to format decimal values using the given width
976 and precision fields:
977 
978  typedef float ns__PH "%5.2f" 0.0 : 14.0;
979 
980 This maps to a simpleType restriction of xsd:float in the soapcpp2-generated
981 schema:
982 
983  <simpleType name="PH">
984  <restriction base="xsd:float">
985  <totalDigits value="5"/>
986  <fractionDigits value="2"/>
987  <minInclusive value="0"/>
988  <maxInclusive value="14"/>
989  </restriction>
990  </simpleType>
991 
992 For exclusive bounds, we use the `<` operator instead of the `:` range
993 operator:
994 
995  typedef float ns__epsilon 0.0 < 1.0;
996 
997 Values `eps` of `ns__epsilon` are restricted between `0.0 < eps < 1.0`.
998 
999 This maps to a simpleType restriction of xsd:float in the soapcpp2-generated
1000 schema:
1001 
1002  <simpleType name="epsilon">
1003  <restriction base="xsd:float">
1004  <minExclusive value="0"/>
1005  <maxExclusive value="1"/>
1006  </restriction>
1007  </simpleType>
1008 
1009 To make just one of the bounds exclusive, while keeping the other bound
1010 inclusive, we add a `<` on the left or on the right side of the range ':'
1011 operator. For example:
1012 
1013  typedef float ns__pos 0.0 < : ; // 0.0 < pos
1014  typedef float ns__neg : < 0.0 ; // neg < 0.0
1015 
1016 It is valid to make both left and right side exclusive with `< : <` which is in
1017 fact identical to the exlusive range `<` operator:
1018 
1019  typedef float ns__epsilon 0.0 < : < 1.0; // 0.0 < eps < 1.0
1020 
1021 It helps to think of the `:` as a placeholder of the value between the two
1022 bounds, which is easier to memorize than the shorthand forms of bounds from
1023 which the `:` is removed:
1024 
1025 | Bounds | Validation check | Shorthand |
1026 | ---------- | ---------------- | --------- |
1027 | 1 : | 1 <= x | 1 |
1028 | 1 : 10 | 1 <= x <= 10 | |
1029 | : 10 | x <= 10 | |
1030 | 1 < : < 10 | 1 < x < 10 | 1 < 10 |
1031 | 1 : < 10 | 1 <= x < 10 | |
1032 | : < 10 | x < 10 | < 10 |
1033 | 1 < : | 1 < x | 1 < |
1034 | 1 < : 10 | 1 < x <= 10 | |
1035 
1036 Besides `float`, also `double` and `long double` values can be restricted. For
1037 example, consider a nonzero probability extended floating point precision type:
1038 
1039  #import "custom/long_double.h"
1040  typedef long double ns__probability "%16Lg" 0.0 < : 1.0;
1041 
1042 Value range restrictions are validated by the parser for all inbound XML data.
1043 A type fault `SOAP_TYPE` will be thrown by the deserializer if the value is out
1044 of range.
1045 
1046 Finally, if your system supports `__int128_t` then you can also use this 128
1047 bit integer type with a custom serializer:
1048 
1049  #import "custom/int128.h"
1050  ... use xsd__integer ...
1051 
1052 We use the `xsd__integer` alias of `__int128_t`, which has a serializer. Do not
1053 use `__int128_t` directly, which is transient (not serializable).
1054 
1055 To convert numeric values to a string, we use the auto-generated function for
1056 numeric type `T`:
1057 
1058  const char *soap_T2s(struct soap*, T val)
1059 
1060 For numeric types `T`, the string returned is stored in an internal buffer, so
1061 you MUST copy it to keep it from being overwritten. For example, use
1062 `soap_strdup(struct soap*, const char*)`.
1063 
1064 To convert a string to a numeric value, we use the auto-generated function
1065 
1066  int soap_s2T(struct soap*, const char *str, T *val)
1067 
1068 where `T` is for example `int`, `LONG64`, `float`, `decimal` (the custom
1069 serializer name of `long double`) or `xsd__integer` (the custom serializer name
1070 of `__int128_t`). The function `soap_s2T` returns `SOAP_OK` on success or an
1071 error when the value is not numeric. For floating point types, "INF", "-INF"
1072 and "NaN" are valid strings to convert to numbers.
1073 
1074 
1075 String types {#toxsd6}
1076 ------------
1077 
1078 String types are mapped to the built-in xsd:string and xsd:QName XSD types.
1079 
1080 The wide strings `wchar_t*` and `std::wstring` may contain Unicode that is
1081 preserved in the XML value space.
1082 
1083 Strings `char*` and `std::string` can only contain extended Latin, but we can
1084 store UTF-8 content that is preserved in the XML value space when the `struct
1085 soap` context is initialized with the flag `XML_C_UTFSTRING`.
1086 
1087 @warning Beware that many XML 1.0 parsers reject all control characters (those
1088 between `#x1` and `#x1F`) except `#x9`, `#xA`, and `#xD`. With the newer XML
1089 1.1 version parsers (including gSOAP) you should be fine.
1090 
1091 The length of a string of a typedef-defined string type can be restricted:
1092 
1093  typedef std::string ns__password 6 : 16;
1094 
1095 which maps to a simpleType restriction of xsd:string in the soapcpp2-generated
1096 schema:
1097 
1098  <simpleType name="password">
1099  <restriction base="xsd:string">
1100  <minLength value="6"/>
1101  <maxLength value="16"/>
1102  </restriction>
1103  </simpleType>
1104 
1105 String length restrictions are validated by the parser for inbound XML data.
1106 A value length fault `SOAP_LENGTH` will be thrown by the deserializer if the
1107 string is too long or too short.
1108 
1109 In addition, an XSD regex pattern restriction can be associated with a string
1110 typedef:
1111 
1112  typedef std::string ns__password "([a-zA-Z]|[0-9]|-)+" 6 : 16;
1113 
1114 which maps to a simpleType restriction of xsd:string in the soapcpp2-generated
1115 schema:
1116 
1117  <simpleType name="password">
1118  <restriction base="xsd:string">
1119  <pattern value="([a-zA-Z0-9]|-)+"/>
1120  <minLength value="6"/>
1121  <maxLength value="16"/>
1122  </restriction>
1123  </simpleType>
1124 
1125 Pattern restrictions are validated by the parser for inbound XML data only if
1126 the `soap::fsvalidate` and `soap::fwvalidate` callbacks are defined, see the
1127 gSOAP user guide for more details.
1128 
1129 Exclusive length bounds can be used with strings:
1130 
1131  typedef std::string ns__string255 : < 256; // same as 0 : 255
1132 
1133 Fixed-size strings (`char[N]`) are rare occurrences in the wild, but apparently
1134 still used in some projects to store strings. To facilitate fixed-size string
1135 serialization, use soapcpp2 option `-b`. For example:
1136 
1137  typedef char ns__buffer[10]; // requires soapcpp2 option -b
1138 
1139 which maps to a simpleType restriction of xsd:string in the soapcpp2-generated
1140 schema:
1141 
1142  <simpleType name="buffer">
1143  <restriction base="xsd:string">
1144  <maxLength value="9"/>
1145  </restriction>
1146  </simpleType>
1147 
1148 Note that fixed-size strings MUST contain NUL-terminated text and SHOULD NOT
1149 contain raw binary data. Also, the length limitation is more restrictive for
1150 UTF-8 content (enabled with the `SOAP_C_UTFSTRING`) that requires multibyte
1151 character encodings. As a consequence, UTF-8 content may be truncated to fit.
1152 
1153 Note that raw binary data can be stored in a `xsd__base64Binary` or
1154 `xsd__hexBinary` structure, or transmitted as a MIME attachment.
1155 
1156 The built-in `_QName` type is a regular C string type (`char*`) that maps to
1157 xsd:QName but has the added advantage that it holds normalized qualified names.
1158 There are actually two forms of normalized QName content, to ensure any QName
1159 is represented accurately and uniquely:
1160 
1161  prefix:name
1162  "URI":name
1163 
1164 where the first form is used when the prefix (and the binding URI) is defined
1165 in the namespace table and is bound to a URI (see the .nsmap file). The second
1166 form is used when the URI is not defined in the namespace table and therefore
1167 no prefix is available to bind and normalize the URI to.
1168 
1169 A `_QName` string may contain a sequence of space-separated QName values, not
1170 just one, and all QName values are normalized to the format shown above.
1171 
1172 To define a `std::string` base type for xsd:QName, we use a typedef:
1173 
1174  typedef std::string xsd__QName;
1175 
1176 The `xsd__QName` string content is normalized, just as with the `_QName`
1177 normalization.
1178 
1179 To serialize strings that contain literal XML content to be reproduced in the
1180 XML value space, use the built-in `_XML` string type, which is a regular C
1181 string type (`char*`) that maps to plain XML CDATA.
1182 
1183 To define a `std::string` base type for literal XML content, use a typedef:
1184 
1185  typedef std::string XML;
1186 
1187 Strings can hold any of the values of the XSD built-in primitive types. We can
1188 use a string typedef to declare the use of the string type as a XSD built-in
1189 type:
1190 
1191  typedef std::string xsd__token;
1192 
1193 We MUST ensure that the string values we populate in this type conform to the
1194 XML standard, which in case of xsd:token is: the lexical and value spaces of
1195 xsd:token are the sets of all strings after whitespace replacement of any
1196 occurrence of `#x9`, `#xA` , and `#xD` by `#x20` and collapsing.
1197 
1198 To copy `char*` or `wchar_t*` strings with a context that manages the allocated
1199 memory, use functions
1200 
1201  char *soap_strdup(struct soap*, const char*)
1202  wchar_t *soap_wstrdup(struct soap*, const wchar_t*)
1203 
1204 To convert a wide string to a UTF-8 encoded string, use function
1205 
1206  const char* SOAP_FMAC2 soap_wchar2s(struct soap*, const wchar_t *s)
1207 
1208 The function allocates and returns a string, with its memory being managed by
1209 the context.
1210 
1211 To convert a UTF-8 encoded string to a wide string, use function
1212 
1213  int soap_s2wchar(struct soap*, const char *from, wchar_t **to, long minlen, long maxlen)
1214 
1215 where `to` is set to point to an allocated `wchar_t*` string. Pass `-1` for
1216 `minlen` and `maxlen` to ignore length constraints on the target string. The
1217 function returns `SOAP_OK` or an error when the length constraints are not met.
1218 
1219 
1220 Date and time types {#toxsd7}
1221 -------------------
1222 
1223 The C/C++ `time_t` type is mapped to the built-in xsd:dateTime XSD type that
1224 represents a date and time within a time zone (typically UTC).
1225 
1226 The XML value space contains ISO 8601 Gregorian time instances of the form
1227 `[-]CCYY-MM-DDThh:mm:ss.sss[Z|(+|-)hh:mm]`, where `Z` is the UTC time zone or a
1228 time zone offset `(+|-)hh:mm]` from UTC is used.
1229 
1230 A `time_t` value is considered and represented in UTC by the serializer.
1231 
1232 Because the `time_t` value range is restricted to dates after 01/01/1970, care
1233 must be taken to ensure the range of xsd:dateTime values in XML exchanges do
1234 not exceed the `time_t` range.
1235 
1236 This restriction does not hold for `struct tm` (`<time.h>`), which we can use
1237 to store and exchange a date and time in UTC without date range restrictions.
1238 The serializer uses the `struct tm` members directly for the XML value space of
1239 xsd:dateTime:
1240 
1241  struct tm
1242  {
1243  int tm_sec; // seconds (0 - 60)
1244  int tm_min; // minutes (0 - 59)
1245  int tm_hour; // hours (0 - 23)
1246  int tm_mday; // day of month (1 - 31)
1247  int tm_mon; // month of year (0 - 11)
1248  int tm_year; // year - 1900
1249  int tm_wday; // day of week (Sunday = 0) (NOT USED)
1250  int tm_yday; // day of year (0 - 365) (NOT USED)
1251  int tm_isdst; // is summer time in effect?
1252  char* tm_zone; // abbreviation of timezone (NOT USED)
1253  };
1254 
1255 You will lose the day of the week information. It is always Sunday
1256 (`tm_wday=0`) and the day of the year is not set either. The time zone is UTC.
1257 
1258 This `struct tm` type is mapped to the built-in xsd:dateTime XSD type and
1259 serialized with the custom serializer `custom/struct_tm.h` that declares a
1260 `xsd__dateTime` type:
1261 
1262  #import "custom/struct_tm.h" // import typedef struct tm xsd__dateTime;
1263  ... use xsd__dateTime ...
1264 
1265 Compile and link your code with `custom/struct_tm.c`.
1266 
1267 The `struct timeval` (`<sys/time.h>`) type is mapped to the built-in
1268 xsd:dateTime XSD type and serialized with the custom serializer
1269 `custom/struct_timeval.h` that declares a `xsd__dateTime` type:
1270 
1271  #import "custom/struct_timeval.h" // import typedef struct timeval xsd__dateTime;
1272  ... use xsd__dateTime ...
1273 
1274 Compile and link your code with `custom/struct_timeval.c`.
1275 
1276 Note that the same value range restrictions apply to `struct timeval` as they
1277 apply to `time_t`. The added benefit of `struct timeval` is the addition of
1278 a microsecond-precise clock:
1279 
1280  struct timeval
1281  {
1282  time_t tv_sec; // seconds since Jan. 1, 1970
1283  suseconds_t tv_usec; // and microseconds
1284  };
1285 
1286 A C++11 `std::chrono::system_clock::time_point` type is mapped to the built-in
1287 xsd:dateTime XSD type and serialized with the custom serializer
1288 `custom/chrono_time_point.h` that declares a `xsd__dateTime` type:
1289 
1290  #import "custom/chrono_time_point.h" // import typedef std::chrono::system_clock::time_point xsd__dateTime;
1291  ... use xsd__dateTime ...
1292 
1293 Compile and link your code with `custom/chrono_time_point.cpp`.
1294 
1295 The `struct tm` type is mapped to the built-in xsd:date XSD type and serialized
1296 with the custom serializer `custom/struct_tm_date.h` that declares a
1297 `xsd__date` type:
1298 
1299  #import "custom/struct_tm_date.h" // import typedef struct tm xsd__date;
1300  ... use xsd__date ...
1301 
1302 Compile and link your code with `custom/struct_tm_date.c`.
1303 
1304 The XML value space of xsd:date are Gregorian calendar dates of the form
1305 `[-]CCYY-MM-DD[Z|(+|-)hh:mm]` with a time zone.
1306 
1307 The serializer ignores the time part and the deserializer only populates the
1308 date part of the struct, setting the time to 00:00:00. There is no unreasonable
1309 limit on the date range because the year field is stored as an integer (`int`).
1310 
1311 An `unsigned long long` (`ULONG64` or `uint64_t`) type that contains a 24 hour
1312 time in microseconds UTC is mapped to the built-in xsd:time XSD type and
1313 serialized with the custom serializer `custom/long_time.h` that declares a
1314 `xsd__time` type:
1315 
1316  #import "custom/long_time.h" // import typedef unsigned long long xsd__time;
1317  ... use xsd__time ...
1318 
1319 Compile and link your code with `custom/long_time.c`.
1320 
1321 This type represents 00:00:00.000000 to 23:59:59.999999, from `0` to an upper
1322 bound of `86399999999`. A microsecond resolution means that a 1 second
1323 increment requires an increment of 1000000 in the integer value.
1324 
1325 The XML value space of xsd:time are points in time recurring each day of the
1326 form `hh:mm:ss.sss[Z|(+|-)hh:mm]`, where `Z` is the UTC time zone or a time
1327 zone offset from UTC is used. The `xsd__time` value is always considered and
1328 represented in UTC by the serializer.
1329 
1330 To convert date and/or time values to a string, we use the auto-generated
1331 function for type `T`:
1332 
1333  const char *soap_T2s(struct soap*, T val)
1334 
1335 For date and time types `T`, the string returned is stored in an internal
1336 buffer, so you MUST copy it to keep it from being overwritten. For example,
1337 use `soap_strdup(struct soap*, const char*)`.
1338 
1339 To convert a string to a date/time value, we use the auto-generated function
1340 
1341  int soap_s2T(struct soap*, const char *str, T *val)
1342 
1343 where `T` is for example `dateTime` (for `time_t`), `xsd__dateTime` (for
1344 `struct tm`, `struct timeval`, or `std::chrono::system_clock::time_point`).
1345 The function `soap_s2T` returns `SOAP_OK` on success or an error when the value
1346 is not a date/time.
1347 
1348 
1349 Time duration types {#toxsd8}
1350 -------------------
1351 
1352 The XML value space of xsd:duration are values of the form `PnYnMnDTnHnMnS`
1353 where the capital letters are delimiters. Delimiters may be omitted when the
1354 corresponding member is not used.
1355 
1356 A `long long` (`LONG64` or `int64_t`) type that contains a duration (time
1357 lapse) in milliseconds is mapped to the built-in xsd:duration XSD type and
1358 serialized with the custom serializer `custom/duration.h` that declares a
1359 `xsd__duration` type:
1360 
1361  #import "custom/duration.h" // import typedef long long xsd__duration;
1362  ... use xsd__duration ...
1363 
1364 Compile and link your code with `custom/duration.c`.
1365 
1366 The duration type `xsd__duration` can represent 106,751,991,167 days forward
1367 and backward with millisecond precision.
1368 
1369 Durations that exceed a month are always output in days, rather than months to
1370 avoid days-per-month conversion inacurracies.
1371 
1372 Durations that are received in years and months instead of total number of days
1373 from a reference point are not well defined, since there is no accepted
1374 reference time point (it may or may not be the current time). The decoder
1375 simple assumes that there are 30 days per month. For example, conversion of
1376 "P4M" gives 120 days. Therefore, the durations "P4M" and "P120D" are assumed
1377 to be identical, which is not necessarily true depending on the reference point
1378 in time.
1379 
1380 Rescaling of the duration value by may be needed when adding the duration value
1381 to a `time_t` value, because `time_t` may or may not have a seconds resolution,
1382 depending on the platform and possible changes to `time_t`.
1383 
1384 Rescaling is done automatically when you add a C++11 `std::chrono::nanoseconds`
1385 value to a `std::chrono::system_clock::time_point` value. To use
1386 `std::chrono::nanoseconds` as xsd:duration:
1387 
1388  #import "custom/chrono_duration.h" // import typedef std::chrono::duration xsd__duration;
1389  ... use xsd__duration ...
1390 
1391 Compile and link your code with `custom/chrono_duration.cpp`.
1392 
1393 This type can represent 384,307,168 days (2^63 nanoseconds) forwards and
1394 backwards in time in increments of 1 ns (1/1000000000 second).
1395 
1396 The same observations with respect to receiving durations in years and months
1397 apply to this serializer's decoder.
1398 
1399 To convert duration values to a string, we use the auto-generated function
1400 
1401  const char *soap_xsd__duration2s(struct soap*, xsd__duration val)
1402 
1403 The string returned is stored in an internal buffer, so you MUST copy it to
1404 keep it from being overwritten, Use `soap_strdup(struct soap*, const char*)`
1405 for example,
1406 
1407 To convert a string to a duration value, we use the auto-generated function
1408 
1409  int soap_s2xsd__dateTime(struct soap*, const char *str, xsd__dateTime *val)
1410 
1411 The function returns `SOAP_OK` on success or an error when the value is not a
1412 duration.
1413 
1414 
1415 Classes and structs {#toxsd9}
1416 -------------------
1417 
1418 Classes and structs are mapped to XSD complexTypes. The XML value space
1419 consists of XML elements with attributes and subelements, possibly constrained
1420 by validation rules that enforce element and attribute occurrence contraints,
1421 numerical value range constraints, and string length and pattern constraints.
1422 
1423 Classes that are declared with the gSOAP tools are limited to single
1424 inheritence only. Structs cannot be inherited.
1425 
1426 The class and struct name is bound to an XML namespace by means of the prefix
1427 naming convention or by using [Colon notation](#toxsd1):
1428 
1429  //gsoap ns schema namespace: urn:types
1430  class ns__record
1431  {
1432  public:
1433  std::string name;
1434  uint64_t SSN;
1435  ns__record *spouse;
1436  ns__record();
1437  ~ns__record();
1438  protected:
1439  struct soap *soap;
1440  };
1441 
1442 In the example above, we also added a context pointer to the `struct soap` that
1443 manages this instance. It is set when the instance is created in the engine's
1444 context, for example when deserialized and populated by the engine.
1445 
1446 The class maps to a complexType in the soapcpp2-generated schema:
1447 
1448  <complexType name="record">
1449  <sequence>
1450  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="1"/>
1451  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
1452  <element name="spouse" type="ns:record" minOccurs="0" maxOccurs="1" nillable="true"/>
1453  </sequence>
1454  </complexType>
1455 
1456 ### Serializable versus transient types and members {#toxsd9-1}
1457 
1458 Public data members of a class or struct are serialized. Private and protected
1459 members are transient and not serializable.
1460 
1461 Also `const` and `static` members are not serializable, with the exception of
1462 `const char*` and `const wchar_t*`.
1463 
1464 Types and specific class/struct members can be made transient by using the
1465 `extern` qualifier:
1466 
1467  extern class std::ostream; // declare 'std::ostream' transient
1468  class ns__record
1469  {
1470  public:
1471  extern int num; // not serialized
1472  std::ostream out; // not serialized
1473  static const int MAX = 1024; // not serialized
1474  };
1475 
1476 By declaring `std::ostream` transient we can use this type where we need it and
1477 without soapcpp2 complaining that this class is not defined.
1478 
1479 ### Volatile classes and structs {#toxsd9-2}
1480 
1481 Classes and structs can be declared `volatile` with the gSOAP tools. This means
1482 that they are already declared elsewhere in our project's source code. We do
1483 not want soapcpp2 to generate a second definition for these types.
1484 
1485 For example, `struct tm` is declared in `<time.h>`. We want it serializable and
1486 serialize only a selection of its data members:
1487 
1488  volatile struct tm
1489  {
1490  int tm_sec; // seconds (0 - 60)
1491  int tm_min; // minutes (0 - 59)
1492  int tm_hour; // hours (0 - 23)
1493  int tm_mday; // day of month (1 - 31)
1494  int tm_mon; // month of year (0 - 11)
1495  int tm_year; // year - 1900
1496  };
1497 
1498 We can declare classes and structs `volatile` for any such types we want to
1499 serialize by only providing the public data members we want to serialize.
1500 
1501 Colon notation comes in handy to bind an existing class or struct to a schema.
1502 For example, we can change the `tm` name as follows without affecting the code
1503 that uses `struct tm` generated by soapcpp2:
1504 
1505  volatile struct ns:tm { ... }
1506 
1507 This struct maps to a complexType in the soapcpp2-generated schema:
1508 
1509  <complexType name="tm">
1510  <sequence>
1511  <element name="tm-sec" type="xsd:int" minOccurs="1" maxOccurs="1"/>
1512  <element name="tm-min" type="xsd:int" minOccurs="1" maxOccurs="1"/>
1513  <element name="tm-hour" type="xsd:int" minOccurs="1" maxOccurs="1"/>
1514  <element name="tm-mday" type="xsd:int" minOccurs="1" maxOccurs="1"/>
1515  <element name="tm-mon" type="xsd:int" minOccurs="1" maxOccurs="1"/>
1516  <element name="tm-year" type="xsd:int" minOccurs="1" maxOccurs="1"/>
1517  </sequence>
1518  </complexType>
1519 
1520 ### Mutable classes and structs {#toxsd9-3}
1521 
1522 Classes and structs can be declared `mutable` with the gSOAP tools. This means
1523 that their definition can be spread out over the source code. This promotes the
1524 concept of a class or struct as a *row of named values*, also known as a *named
1525 tuple*, that can be extended at compile time in our source code with additional
1526 members. Because these types differ from the traditional object-oriented
1527 principles and design concepts of classes and objects, constructors and
1528 destructors cannot be defined (also because we cannot guarantee merging these
1529 into one such that all members will be initialized). A default constructor,
1530 copy constructor, assignment operation, and destructor will be assigned
1531 automatically by soapcpp2.
1532 
1533  mutable struct ns__tuple
1534  {
1535  @std::string id;
1536  };
1537 
1538  mutable struct ns__tuple
1539  {
1540  std::string name;
1541  std::string value;
1542  };
1543 
1544 The members are collected into one definition generated by soapcpp2. Members
1545 may be repeated from one definition to another, but only if their associated
1546 types are identical. So, for example, a third extension with a `value` member
1547 with a different type fails:
1548 
1549  mutable struct ns__tuple
1550  {
1551  float value; // BAD: value is already declared std::string
1552  };
1553 
1554 The `mutable` concept has proven to be very useful when declaring and
1555 collecting SOAP Headers for multiple services, which are collected into one
1556 `struct SOAP_ENV__Header` by the soapcpp2 tool.
1557 
1558 ### Default member values in C and C++ {#toxsd9-4}
1559 
1560 Class and struct data members in C and C++ may be declared with an optional
1561 default initialization value that is provided "inline" with the declaration of
1562 the member:
1563 
1564  class ns__record
1565  {
1566  public:
1567  std::string name = "Joe";
1568 
1569 These initializations are made by the default constructor that is added by
1570 soapcpp2 to each class and struct. A constructor is only added when a default
1571 constructor is not already defined with the class declaration. You can
1572 explicitly (re)initialize an object with the auto-generated
1573 `soap_default(struct soap*)` method of a class and the auto-generated
1574 `soap_default_T(struct soap*, T*)` function for a struct `T` in C and C++.
1575 
1576 Initializations can only be provided for members that have primitive types
1577 (`bool`, `enum`, `time_t`, numeric and string types).
1578 
1579 ### Attribute members {#toxsd9-5}
1580 
1581 Class and struct data members can be declared as XML attributes by annotating
1582 their type with a `@` with the declaration of the member:
1583 
1584  class ns__record
1585  {
1586  public:
1587  @std::string name;
1588  @uint64_t SSN;
1589  ns__record *spouse;
1590  };
1591 
1592 This class maps to a complexType in the soapcpp2-generated schema:
1593 
1594  <complexType name="record">
1595  <sequence>
1596  <element name="spouse" type="ns:record" minOccurs="0" maxOccurs="1" nillable="true"/>
1597  </sequence>
1598  <attribute name="name" type="xsd:string" use="required"/>
1599  <attribute name="SSN" type="xsd:unsignedLong" use="required"/>
1600  </complexType>
1601 
1602 An example XML instance of `ns__record` is:
1603 
1604  <ns:record xmlns:ns="urn:types" name="Joe" SSN="1234567890">
1605  <spouse>
1606  <name>Jane</name>
1607  <SSN>1987654320</SSN>
1608  </spouse>
1609  </ns:record>
1610 
1611 Attribute data members are restricted to primitive types (`bool`, `enum`,
1612 `time_t`, numeric and string types), `xsd__hexBinary`, `xsd__base64Binary`, and
1613 custom serializers, such as `xsd__dateTime`. Custom serializers for types that
1614 may be used as attributes MUST define `soap_s2T` and `soap_T2s` functions that
1615 convert values of type `T` to strings and back.
1616 
1617 Attribute data members can be pointers and smart pointers to these types, which
1618 permits attributes to be optional.
1619 
1620 ### (Smart) pointer members and their occurrence constraints {#toxsd9-6}
1621 
1622 A public pointer-typed data member is serialized by following its (smart)
1623 pointer(s) to the value pointed to.
1624 
1625 Pointers that are NULL and smart pointers that are empty are serialized to
1626 produce omitted element and attribute values, unless an element is required
1627 and is nillable.
1628 
1629 To control the occurrence requirements of pointer-based data members,
1630 occurrence constraints are associated with data members in the form of a range
1631 `minOccurs : maxOccurs`. For non-repeatable (meaning, not a container or array)
1632 data members, there are only three reasonable occurrence constraints:
1633 
1634 - `0:0` means that this element or attribute is prohibited.
1635 - `0:1` means that this element or attribute is optional.
1636 - `1:1` means that this element or attribute is required.
1637 
1638 Pointer-based data members have a default `0:1` occurrence constraint, making
1639 them optional, and their XSD schema local element/attribute definition is
1640 marked as nillable. Non-pointer data members have a default `1:1` occurence
1641 constraint, making them required.
1642 
1643 A pointer data member that is explicitly marked as required with `1:1` will be
1644 serialized as an element with an xsi:nil attribute, thus effectively revealing
1645 the NULL property of its value.
1646 
1647 A non-pointer data member that is explicitly marked as optional with `0:1` will
1648 be set to its default value when no XML value is presented to the deserializer.
1649 A default value can be assigned to data members that have primitive types.
1650 
1651 Consider for example:
1652 
1653  class ns__record
1654  {
1655  public:
1656  std::shared_ptr<std::string> name; // optional (0:1)
1657  uint64_t SSN 0:1 = 999; // forced this to be optional with default 999
1658  ns__record *spouse 1:1; // forced this to be required (only married people)
1659  };
1660 
1661 This class maps to a complexType in the soapcpp2-generated schema:
1662 
1663  <complexType name="record">
1664  <sequence>
1665  <element name="name" type="xsd:string" minOccurs="0" maxOccurs="1" nillable="true"/>
1666  <element name="SSN" type="xsd:unsignedLong" minOccurs="0" maxOccurs="1" default="999"/>
1667  <element name="spouse" type="ns:record" minOccurs="1" maxOccurs="1" nillable="true"/>
1668  </sequence>
1669  </complexType>
1670 
1671 An example XML instance of `ns__record` with its `name` string value set to
1672 `Joe`, `SSN` set to its default, and `spouse` set to NULL:
1673 
1674  <ns:record xmlns:ns="urn:types">
1675  <name>Joe</name>
1676  <SSN>999</SSN>
1677  <spouse xsi:nil="true"/>
1678  </ns:record>
1679 
1680 @note In general, a smart pointer is simply declared as a `volatile` template
1681 in a gSOAP header file for soapcpp2:
1682 
1683  volatile template <class T> class NAMESPACE::shared_ptr;
1684 
1685 @note The soapcpp2 tool generates code that uses `NAMESPACE::shared_ptr` and
1686 `NAMESPACE::make_shared` to create shared pointers to objects, where
1687 `NAMESPACE` is any valid C++ namespace such as `std` and `boost` if you have
1688 Boost installed.
1689 
1690 ### Container members and their occurrence constraints {#toxsd9-7}
1691 
1692 Class and struct data member types that are containers `std::deque`,
1693 `std::list`, `std::vector` and `std::set` are serialized as a collections
1694 of values.
1695 
1696 You can use `std::deque`, `std::list`, `std::vector`, and `std::set` containers by importing:
1697 
1698  #import "import/stl.h" // import all containers
1699  #import "import/stldeque.h" // import deque
1700  #import "import/stllist.h" // import list
1701  #import "import/stlvector.h" // import vector
1702  #import "import/stlset.h" // import set
1703 
1704 For example, to use a vector data mamber to store names in a record:
1705 
1706  #import "import/stlvector.h"
1707  class ns__record
1708  {
1709  public:
1710  std::vector<std::string> names;
1711  uint64_t SSN;
1712  };
1713 
1714 To limit the number of names in the vector within reasonable bounds, occurrence
1715 constraints are associated with the container. Occurrence constraints are of
1716 the form `minOccurs : maxOccurs`:
1717 
1718  #import "import/stlvector.h"
1719  class ns__record
1720  {
1721  public:
1722  std::vector<std::string> names 1:10;
1723  uint64_t SSN;
1724  };
1725 
1726 This class maps to a complexType in the soapcpp2-generated schema:
1727 
1728  <complexType name="record">
1729  <sequence>
1730  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="10"/>
1731  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1""/>
1732  </sequence>
1733  </complexType>
1734 
1735 @note In general, a container is simply declared as a template in a gSOAP
1736 header file for soapcpp2. All class templates are considered containers
1737 (except when declared `volatile`, see smart pointers). For example,
1738 `std::vector` is declared in `gsoap/import/stlvector.h` as:
1739 
1740  template <class T> class std::vector;
1741 
1742 @note You can define and use your own containers. The soapcpp2 tool generates
1743 code that uses the following members of the `template <typename T> class C`
1744 container:
1745 
1746  void C::clear()
1747  C::iterator C::begin()
1748  C::const_iterator C::begin() const
1749  C::iterator C::end()
1750  C::const_iterator C::end() const
1751  size_t C::size() const
1752  C::iterator C::insert(C::iterator pos, const T& val)
1753 
1754 @note For more details see the example `simple_vector` container with
1755 documentation in the package under `gsoap/samples/template`.
1756 
1757 Because C does not support a container template library, we can use a
1758 dynamically-sized array of values. This array is declared as a size-pointer
1759 member pair:
1760 
1761  struct ns__record
1762  {
1763  $int sizeofnames; // array size
1764  char* *names; // array of char* names
1765  uint64_t SSN;
1766  };
1767 
1768 where the marker `$` with `int` denotes a special type that is used to store
1769 the array size and to indicate that this is a size-pointer member pair that
1770 declares a dynamically-sized array.
1771 
1772 This class maps to a complexType in the soapcpp2-generated schema:
1773 
1774  <complexType name="record">
1775  <sequence>
1776  <element name="name" type="xsd:string" minOccurs="0" maxOccurs="unbounded" nillable="true"/>
1777  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1""/>
1778  </sequence>
1779  </complexType>
1780 
1781 To limit the number of names in the array within reasonable bounds, occurrence
1782 constraints are associated with the array size member. Occurrence constraints
1783 are of the form `minOccurs : maxOccurs`:
1784 
1785  struct ns__record
1786  {
1787  $int sizeofnames 1:10; // array size 1..10
1788  char* *names; // array of one to ten char* names
1789  uint64_t SSN;
1790  };
1791 
1792 This class maps to a complexType in the soapcpp2-generated schema:
1793 
1794  <complexType name="record">
1795  <sequence>
1796  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="10" nillable="true"/>
1797  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1""/>
1798  </sequence>
1799  </complexType>
1800 
1801 ### Union members {#toxsd9-8}
1802 
1803 A union member in a class or in a struct cannot be serialized unless a
1804 discriminating *variant selector* member is provided that tells the serializer
1805 which union field to serialize. This effectively creates a *tagged union*.
1806 
1807 The variant selector is associated with the union as a selector-union member
1808 pair, where the variant selector is a special `$int` member:
1809 
1810  class ns__record
1811  {
1812  public:
1813  $int xORnORs; // variant selector
1814  union choice
1815  {
1816  float x;
1817  int n;
1818  char *s;
1819  } u;
1820  std::string name;
1821  };
1822 
1823 The variant selector values are auto-generated based on the union name `choice`
1824 and the names of its members `x`, `n`, and `s`:
1825 
1826 - `xORnORs = SOAP_UNION_choice_x` when `u.x` is valid.
1827 - `xORnORs = SOAP_UNION_choice_n` when `u.n` is valid.
1828 - `xORnORs = SOAP_UNION_choice_s` when `u.s` is valid.
1829 - `xORnORs = 0` when none are valid (should only be used with great care,
1830  because XML content validation may fail when content is required but absent).
1831 
1832 This class maps to a complexType with a sequence and choice in the
1833 soapcpp2-generated schema:
1834 
1835  <complexType name="record">
1836  <sequence>
1837  <choice>
1838  <element name="x" type="xsd:float" minOccurs="1" maxOccurs="1"/>
1839  <element name="n" type="xsd:int" minOccurs="1" maxOccurs="1"/>
1840  <element name="s" type="xsd:string" minOccurs="0" maxOccurs="1" nillable="true"/>
1841  </choice>
1842  <element name="names" type="xsd:string" minOccurs="1" maxOccurs="10" nillable="true"/>
1843  </sequence>
1844  </complexType>
1845 
1846 ### Adding get and set methods {#toxsd9-9}
1847 
1848 A public `get` method may be added to a class or struct, which will be
1849 triggered by the deserializer. This method will be invoked right after the
1850 instance is populated by the deserializer. The `get` method can be used to
1851 update or verify deserialized content. It should return `SOAP_OK` or set
1852 `soap::error` to a nonzero error code and return it.
1853 
1854 A public `set` method may be added to a class or struct, which will be
1855 triggered by the serializer. The method will be invoked just before the
1856 instance is serialized. Likewise, the `set` method should return `SOAP_OK` or
1857 set set `soap::error` to a nonzero error code and return it.
1858 
1859 For example, adding a `set` and `get` method to a class declaration:
1860 
1861  class ns__record
1862  {
1863  public:
1864  int set(struct soap*); // triggered before serialization
1865  int get(struct soap*); // triggered after deserialization
1866 
1867 To add these and othe rmethods to classes and structs with wsdl2h and
1868 `typemap.dat`, please see [Class/struct member additions](#typemap3).
1869 
1870 ### Defining document root elements {#toxsd9-10}
1871 
1872 To define and reference XML document root elements we use type names that start
1873 with an underscore:
1874 
1875  class _ns__record
1876 
1877 Alternatively, we can use a typedef to define a document root element with a
1878 given type:
1879 
1880  typedef ns__record _ns__record;
1881 
1882 This typedef maps to a global root element that is added to the
1883 soapcpp2-generated schema:
1884 
1885  <element name="record" type="ns:record"/>
1886 
1887 An example XML instance of `_ns__record` is:
1888 
1889  <ns:record xmlns:ns="urn:types">
1890  <name>Joe</name>
1891  <SSN>1234567890</SSN>
1892  <spouse>
1893  <name>Jane</name>
1894  <SSN>1987654320</SSN>
1895  </spouse>
1896  </ns:record>
1897 
1898 Global-level element/attribute definitions are also referenced and/or added to
1899 the generated schema when serializable data members reference these by their
1900 qualified name:
1901 
1902  typedef std::string _ns__name 1 : 100;
1903  class _ns__record
1904  {
1905  public:
1906  @_QName xsi__type; // built-in XSD attribute xsi:type
1907  _ns__name ns__name; // ref to global ns:name element
1908  uint64_t SSN;
1909  _ns__record *spouse;
1910  };
1911 
1912 These types map to the following comonents in the soapcpp2-generated schema:
1913 
1914  <simpleType name="name">
1915  <restriction base="xsd:string">
1916  <minLength value="1"/>
1917  <maxLength value="100"/>
1918  </restriction>
1919  </simpleType>
1920  <element name="name" type="ns:name"/>
1921  <complexType name="record">
1922  <sequence>
1923  <element ref="ns:name" minOccurs="1" maxOccurs="1"/>
1924  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
1925  <element name="spouse" type="ns:record" minOccurs="0" maxOccurs="1" nillable="true"/>
1926  </sequence>
1927  <attribute ref="xsi:type" use="optional"/>
1928  </complexType>
1929  <element name="record" type="ns:record"/>
1930 
1931 @warning Use only use qualified member names when their types match the root
1932 element types that they refer to. For example:
1933 
1934  class _ns__record
1935  {
1936  public:
1937  int ns__name; // BAD: element ns:name is NOT of an int type
1938 
1939 @warning Therefore, we recommend to avoid qualified member names and only use
1940 them when referring to standard XSD elements and attributes, such as
1941 `xsi__type`, and `xsd__lang`. The soapcpp2 tool does not prevent abuse of this
1942 mechanism.
1943 
1944 ### Operations on classes and structs {#toxsd9-11}
1945 
1946 The following functions/macros are generated by soapcpp2 for each type `T`,
1947 which should make it easier to send, receive, and copy XML data in C and in
1948 C++:
1949 
1950 - `int soap_write_T(struct soap*, T*)` writes an instance of `T` to a FILE (via
1951  `FILE *soap::sendfd)`) or to a stream (via `std::ostream *soap::os`).
1952  Returns `SOAP_OK` on success or an error code, also stored in `soap->error`.
1953 
1954 - `int soap_read_T(struct soap*, T*)` reads an instance of `T` from a FILE (via
1955  `FILE *soap::recvfd)`) or from a stream (via `std::istream *soap::is`).
1956  Returns `SOAP_OK` on success or an error code, also stored in `soap->error`.
1957 
1958 - `void soap_default_T(struct soap*, T*)` sets an instance `T` to its default
1959  value, resetting members of a struct to their initial values (for classes we
1960  use method `T::soap_default`, see below).
1961 
1962 - `T * soap_dup_T(struct soap*, T *dst, const T *src)` (soapcpp2 option `-Ec`)
1963  deep copy `src` into `dst`, replicating all deep cycles and shared pointers
1964  when a managing soap context is provided as argument. When `dst` is NULL,
1965  allocates space for `dst`. Deep copy is a tree when argument is NULL, but the
1966  presence of deep cycles will lead to non-termination. Use flag
1967  `SOAP_XML_TREE` with managing context to copy into a tree without cycles and
1968  pointers to shared objects. Returns `dst` (or allocated space when `dst` is
1969  NULL).
1970 
1971 - `void soap_del_T(const T*)` (soapcpp2 option `-Ed`) deletes all
1972  heap-allocated members of this object by deep deletion ONLY IF this object
1973  and all of its (deep) members are not managed by a soap context AND the deep
1974  structure is a tree (no cycles and co-referenced objects by way of multiple
1975  (non-smart) pointers pointing to the same data). Can be safely used after
1976  `soap_dup(NULL)` to delete the deep copy. Does not delete the object itself.
1977 
1978 When in C++ mode, soapcpp2 tool adds several methods to classes and structs, in
1979 addition to adding a default constructor and destructor (when these were not
1980 explicitly declared).
1981 
1982 The public methods added to a class/struct `T`:
1983 
1984 - `virtual int T::soap_type(void)` returns a unique type ID (`SOAP_TYPE_T`).
1985  This numeric ID can be used to distinguish base from derived instances.
1986 
1987 - `virtual void T::soap_default(struct soap*)` sets all data members to
1988  default values.
1989 
1990 - `virtual void T::soap_serialize(struct soap*) const` serializes object to
1991  prepare for SOAP 1.1/1.2 encoded output (or with `SOAP_XML_GRAPH`) by
1992  analyzing its (cyclic) structures.
1993 
1994 - `virtual int T::soap_put(struct soap*, const char *tag, const char *type) const`
1995  emits object in XML, compliant with SOAP 1.1 encoding style, return error
1996  code or `SOAP_OK`. Requires `soap_begin_send(soap)` and
1997  `soap_end_send(soap)`.
1998 
1999 - `virtual int T::soap_out(struct soap*, const char *tag, int id, const char *type) const`
2000  emits object in XML, with tag and optional id attribute and xsi:type, return
2001  error code or `SOAP_OK`. Requires `soap_begin_send(soap)` and
2002  `soap_end_send(soap)`.
2003 
2004 - `virtual void * T::soap_get(struct soap*, const char *tag, const char *type)`
2005  Get object from XML, compliant with SOAP 1.1 encoding style, return pointer
2006  to object or NULL on error. Requires `soap_begin_recv(soap)` and
2007  `soap_end_recv(soap)`.
2008 
2009 - `virtual void *soap_in(struct soap*, const char *tag, const char *type)`
2010  Get object from XML, with matching tag and type (NULL matches any tag and
2011  type), return pointer to object or NULL on error. Requires
2012  `soap_begin_recv(soap)` and `soap_end_recv(soap)`
2013 
2014 - `virtual T * T::soap_alloc(void) const` returns a new object of type `T`,
2015  default initialized and not managed by a soap context.
2016 
2017 - `virtual T * T::soap_dup(struct soap*) const` (soapcpp2 option `-Ec`) returns
2018  a duplicate of this object by deep copying, replicating all deep cycles and
2019  shared pointers when a managing soap context is provided as argument. Deep
2020  copy is a tree when argument is NULL, but the presence of deep cycles will
2021  lead to non-termination. Use flag `SOAP_XML_TREE` with the managing context
2022  to copy into a tree without cycles and pointers to shared objects.
2023 
2024 - `virtual void T::soap_del() const` (soapcpp2 option `-Ed`) deletes all
2025  heap-allocated members of this object by deep deletion ONLY IF this object
2026  and all of its (deep) members are not managed by a soap context AND the deep
2027  structure is a tree (no cycles and co-referenced objects by way of multiple
2028  (non-smart) pointers pointing to the same data). Can be safely used after
2029  `soap_dup(NULL)` to delete the deep copy. Does not delete the object itself.
2030 
2031 
2032 Special classes and structs {#toxsd10}
2033 ---------------------------
2034 
2035 ### SOAP encoded arrays {#toxsd10-1}
2036 
2037 A class or struct with the following layout is a one-dimensional SOAP encoded
2038 Array type:
2039 
2040  class ArrayOfT
2041  {
2042  public:
2043  T *__ptr; // array pointer
2044  int __size; // array size
2045  };
2046 
2047 where `T` is the array element type. A multidimensional SOAP Array is:
2048 
2049  class ArrayOfT
2050  {
2051  public:
2052  T *__ptr; // array pointer
2053  int __size[N]; // array size of each dimension
2054  };
2055 
2056 where `N` is the constant number of dimensions. The pointer points to an array
2057 of `__size[0]*__size[1]* ... * __size[N-1]` elements.
2058 
2059 This maps to a complexType restriction of SOAP-ENC:Array in the
2060 soapcpp2-generated schema:
2061 
2062  <complexType name="ArrayOfT">
2063  <complexContent>
2064  <restriction base="SOAP-ENC:Array">
2065  <sequence>
2066  <element name="item" type="T" minOccurs="0" maxOccurs="unbounded" nillable="true"/>
2067  </sequence>
2068  <attribute ref="SOAP-ENC:arrayType" WSDL:arrayType="ArrayOfT[]"/>
2069  </restriction>
2070  </complexContent>
2071  </complexType>
2072 
2073 The name of the class can be arbitrary. We often use `ArrayOfT` without a
2074 prefix to distinguish arrays from other classes and structs.
2075 
2076 With SOAP 1.1 encoding, an optional offset member can be added that controls
2077 the start of the index range for each dimension:
2078 
2079  class ArrayOfT
2080  {
2081  public:
2082  T *__ptr; // array pointer
2083  int __size[N]; // array size of each dimension
2084  int __offset[N]; // array offsets to start each dimension
2085  };
2086 
2087 For example, we can define a matrix of floats as follows:
2088 
2089  class Matrix
2090  {
2091  public:
2092  double *__ptr;
2093  int __size[2];
2094  };
2095 
2096 The following code populates the matrix and serializes it in XML:
2097 
2098  soap *soap = soap_new1(SOAP_XML_INDENT);
2099  Matrix A;
2100  double a[6] = { 1, 2, 3, 4, 5, 6 };
2101  A.__ptr = a;
2102  A.__size[0] = 2;
2103  A.__size[1] = 3;
2104  soap_write_Matrix(soap, &A);
2105 
2106 Matrix A is serialized as an array with 2x3 values:
2107 
2108  <SOAP-ENC:Array SOAP-ENC:arrayType="xsd:double[2,3]" ...>
2109  <item>1</item>
2110  <item>2</item>
2111  <item>3</item>
2112  <item>4</item>
2113  <item>5</item>
2114  <item>6</item>
2115  </SOAP-ENC:Array>
2116 
2117 ### XSD hexBinary and base64Binary types {#toxsd10-2}
2118 
2119 A special case of a one-dimensional array is used to define xsd:hexBinary and
2120 xsd:base64Binary types when the pointer type is `unsigned char`:
2121 
2122  class xsd__hexBinary
2123  {
2124  public:
2125  unsigned char *__ptr; // points to raw binary data
2126  int __size; // size of data
2127  };
2128 
2129 and
2130 
2131  class xsd__base64Binary
2132  {
2133  public:
2134  unsigned char *__ptr; // points to raw binary data
2135  int __size; // size of data
2136  };
2137 
2138 ### MIME/MTOM attachment binary types {#toxsd10-3}
2139 
2140 A class or struct with a binary content layout can be extended to support
2141 MIME/MTOM (and older DIME) attachments, such as in xop:Include elements:
2142 
2143  //gsoap xop schema import: http://www.w3.org/2004/08/xop/include
2144  class _xop__Include
2145  {
2146  public:
2147  unsigned char *__ptr; // points to raw binary data
2148  int __size; // size of data
2149  char *id; // NULL to generate an id, or set to a unique UUID
2150  char *type; // MIME type of the data
2151  char *options; // optional description of MIME attachment
2152  };
2153 
2154 Attachments are beyond the scope of this document and we refer to the gSOAP
2155 user guide for more details.
2156 
2157 ### Wrapper class/struct for simpleContent {#toxsd10-4}
2158 
2159 A class or struct with the following layout is a complexType that wraps
2160 simpleContent:
2161 
2162  class ns__simple
2163  {
2164  public:
2165  T __item;
2166  };
2167 
2168 The type `T` is a primitive type (`bool`, `enum`, `time_t`, numeric and string
2169 types), `xsd__hexBinary`, `xsd__base64Binary`, and custom serializers, such as
2170 `xsd__dateTime`.
2171 
2172 This maps to a complexType with simpleContent in the soapcpp2-generated schema:
2173 
2174  <complexType name="simple">
2175  <simpleContent>
2176  <extension base="T"/>
2177  </simpleContent>
2178  </complexType>
2179 
2180 A wrapper class/struct may include any number of attributes declared with `@`.
2181 
2182 
2183 Serialization rules {#rules}
2184 ===================
2185 
2186 A presentation on XML data bindings is not complete without discussing the
2187 serialization rules that put your data in XML on the wire.
2188 
2189 There are several options to choose from to serialize data in XML. The choice
2190 depends on the use of the SOAP protocol or if SOAP is not required. The wsdl2h
2191 tool automates this for you by taking the WSDL transport bindings into account
2192 when generating the service functions in C and C++ that use SOAP or REST.
2193 
2194 The gSOAP tools are not limited to SOAP. The tools implement generic XML data
2195 bindings for SOAP, REST, and other uses of XML. So you can read and write XML
2196 using the serializing [Operations on classes and structs](#toxsd9-11).
2197 
2198 The following sections briefly explain the serialization rules with respect to
2199 the SOAP protocol for XML Web services. A basic understanding of the SOAP
2200 protocol is useful when developing client and server applications that must
2201 interoperate with other SOAP applications.
2202 
2203 SOAP/REST Web service client and service operations are represented as
2204 functions in our gSOAP header file for soapcpp2. The soapcpp2 tool will
2205 translate these function to client-side service invocation calls and
2206 server-side service operation dispatchers.
2207 
2208 A discussion of SOAP clients and servers is beyond the scope of this document.
2209 However, the SOAP options discussed here also apply to SOAP client and server
2210 development.
2211 
2212 
2213 SOAP document versus rpc style {#doc-rpc}
2214 ------------------------------
2215 
2216 The `wsdl:binding/soap:binding/@style` attribute in the wsdl:binding section of
2217 a WSDL is either "document" or "rpc". The "rpc" style refers to SOAP RPC
2218 (Remote Procedure Call), which is more restrictive than the "document" style by
2219 requiring one XML element in the SOAP Body to act as the procedure name with
2220 XML subelements as its parameters.
2221 
2222 For example, the following directives in the gSOAP header file for soapcpp2
2223 declare that `DBupdate` is a SOAP RPC encoding service method:
2224 
2225  //gsoap ns service namespace: urn:DB
2226  //gsoap ns service method-protocol: DBupdate SOAP
2227  //gsoap ns service method-style: DBupdate rpc
2228  int ns__DBupdate(...);
2229 
2230 The XML payload has a SOAP envelope, optional SOAP header, and a SOAP body with
2231 one element representing the operation with the parameters as subelements:
2232 
2233  <SOAP-ENV:Envelope
2234  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
2235  xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
2236  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
2237  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
2238  xmlsn:ns="urn:DB">
2239  <SOAP-ENV:Body>
2240  <ns:DBupdate>
2241  ...
2242  </ns:DBupdate>
2243  </SOAP-ENV:Body>
2244  </SOAP-ENV:Envelope>
2245 
2246 The "document" style puts no restrictions on the SOAP Body content. However, we
2247 recommend that the first element's tag name in the SOAP Body should be unique
2248 to each type of operation, so that the receiver can dispatch the operation
2249 based on this element's tag name. Alternatively, the HTTP URL path can be used
2250 to specify the operation, or the HTTP action header can be used to dispatch
2251 operations automatically on the server side (soapcpp2 options -a and -A).
2252 
2253 
2254 SOAP literal versus encoding {#lit-enc}
2255 ----------------------------
2256 
2257 The `wsdl:operation/soap:body/@use` attribute in the wsdl:binding section of a
2258 WSDL is either "literal" or "encoded". The "encoded" use refers to the SOAP
2259 encoding rules that support id-ref multi-referenced elements to serialize
2260 data as graphs.
2261 
2262 SOAP encoding is very useful if the data internally forms a graph (including
2263 cycles) and we want the graph to be serialized in XML in a format that ensures
2264 that its structure is preserved. In that case, SOAP 1.2 encoding is the best
2265 option.
2266 
2267 SOAP encoding also adds encoding rules for [SOAP arrays](toxsd10) to serialize
2268 multi-dimensional arrays. The use of XML attributes to exchange XML data in
2269 SOAP encoding is not permitted. The only attributes permitted are the standard
2270 XSD attributes, SOAP encoding attributes (such as for arrays), and id-ref.
2271 
2272 For example, the following directives in the gSOAP header file for soapcpp2
2273 declare that `DBupdate` is a SOAP RPC encoding service method:
2274 
2275  //gsoap ns service namespace: urn:DB
2276  //gsoap ns service method-protocol: DBupdate SOAP
2277  //gsoap ns service method-style: DBupdate rpc
2278  //gsoap ns service method-encoding: DBupdate encoded
2279  int ns__DBupdate(...);
2280 
2281 The XML payload has a SOAP envelope, optional SOAP header, and a SOAP body with
2282 an encodingStyle attribute for SOAP 1.1 encoding and an element representing the
2283 operation with parameters that are SOAP 1.1 encoded:
2284 
2285  <SOAP-ENV:Envelope
2286  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
2287  xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
2288  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
2289  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
2290  xmlsn:ns="urn:DB">
2291  <SOAP-ENV:Body SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
2292  <ns:DBupdate>
2293  <records SOAP-ENC:arrayType="ns:record[3]">
2294  <item>
2295  <name href="#_1"/>
2296  <SSN>1234567890</SSN>
2297  </item>
2298  <item>
2299  <name>Jane</name>
2300  <SSN>1987654320</SSN>
2301  </item>
2302  <item>
2303  <name href="#_1"/>
2304  <SSN>2345678901</SSN>
2305  </item>
2306  </records>
2307  </ns:DBupdate>
2308  <id id="_1" xsi:type="xsd:string">Joe</id>
2309  </SOAP-ENV:Body>
2310  </SOAP-ENV:Envelope>
2311 
2312 Note that the name "Joe" is shared by two records and the string is referenced
2313 by SOAP 1.1 href and id attributes.
2314 
2315 While gSOAP only introduces multi-referenced elements in the payload when they
2316 are actually multi-referenced in the data graph, other SOAP applications may
2317 render multi-referenced elements more aggressively. The example could also be
2318 rendered as:
2319 
2320  <SOAP-ENV:Envelope
2321  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
2322  xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
2323  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
2324  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
2325  xmlsn:ns="urn:DB">
2326  <SOAP-ENV:Body SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
2327  <ns:DBupdate>
2328  <records SOAP-ENC:arrayType="ns:record[3]">
2329  <item href="#id1"/>
2330  <item href="#id2"/>
2331  <item href="#id3"/>
2332  </records>
2333  </ns:DBupdate>
2334  <id id="id1" xsi:type="ns:record">
2335  <name href="#id4"/>
2336  <SSN>1234567890</SSN>
2337  </id>
2338  <id id="id2" xsi:type="ns:record">
2339  <name href="#id5"/>
2340  <SSN>1987654320</SSN>
2341  </id>
2342  <id id="id3" xsi:type="ns:record">
2343  <name href="#id4"/>
2344  <SSN>2345678901</SSN>
2345  </id>
2346  <id id="id4" xsi:type="xsd:string">Joe</id>
2347  <id id="id5" xsi:type="xsd:string">Jane</id>
2348  </SOAP-ENV:Body>
2349  </SOAP-ENV:Envelope>
2350 
2351 SOAP 1.2 encoding is cleaner and produces more accurate XML encodings of data
2352 graphs by setting the id attribute on the element that is referenced:
2353 
2354  <SOAP-ENV:Envelope
2355  xmlns:SOAP-ENV="http://www.w3.org/2003/05/soap-envelope"
2356  xmlns:SOAP-ENC="http://www.w3.org/2003/05/soap-encoding"
2357  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
2358  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
2359  xmlsn:ns="urn:DB">
2360  <SOAP-ENV:Body>
2361  <ns:DBupdate SOAP-ENV:encodingStyle="http://www.w3.org/2003/05/soap-encoding">
2362  <records SOAP-ENC:itemType="ns:record" SOAP-ENC:arraySize="3">
2363  <item>
2364  <name SOAP-ENC:id="_1">Joe</name>
2365  <SSN>1234567890</SSN>
2366  </item>
2367  <item>
2368  <name>Jane</name>
2369  <SSN>1987654320</SSN>
2370  </item>
2371  <item>
2372  <name SOAP-ENC:ref="_1"/>
2373  <SSN>2345678901</SSN>
2374  </item>
2375  </records>
2376  </ns:DBupdate>
2377  </SOAP-ENV:Body>
2378  </SOAP-ENV:Envelope>
2379 
2380 @note Some SOAP 1.2 applications consider the namespace `SOAP-ENC` of
2381 `SOAP-ENC:id` and `SOAP-ENC:ref` optional. The gSOAP SOAP 1.2 encoding
2382 serialization follows the 2007 standard, while accepting unqualified id and
2383 ref attributes.
2384 
2385 To remove all rendered id-ref multi-referenced elements in gSOAP, use the
2386 `SOAP_XML_TREE` flag to initialize the gSOAP engine context.
2387 
2388 Some XML validation rules are turned off with SOAP encoding, because of the
2389 presence of additional attributes, such as id and ref/href, SOAP arrays with
2390 arbitrary element tags for array elements, and the occurrence of additional
2391 multi-ref elements in the SOAP 1.1 Body.
2392 
2393 The use of "literal" puts no restrictions on the XML in the SOAP Body. Full
2394 XML validation is possible, which can be enabled with the `SOAP_XML_STRICT`
2395 flag to initialize the gSOAP engine context. However, data graphs will be
2396 serialized as trees and cycles in the data will be cut from the XML rendition.
2397 
2398 
2399 SOAP 1.1 versus SOAP 1.2 {#soap}
2400 ------------------------
2401 
2402 There are two SOAP protocol versions: 1.1 and 1.2. The gSOAP tools can switch
2403 between the two versions seamlessly. You can declare the default SOAP version
2404 for a service operation as follows:
2405 
2406  //gsoap ns service method-protocol: DBupdate SOAP1.2
2407 
2408 The gSOAP soapcpp2 auto-generates client and server code. At the client side,
2409 this operation sends data with SOAP 1.2 but accepts responses also in SOAP 1.1.
2410 At the server side, this operation accepts requests in SOAP 1.1 and 1.2 and
2411 will return responses in the same SOAP version.
2412 
2413 As we discussed in the previous section, the SOAP 1.2 protocol has a cleaner
2414 multi-referenced element serialization format that greatly enhances the
2415 accuracy of data graph serialization with SOAP RPC encoding and is therefore
2416 recommended.
2417 
2418 The SOAP 1.2 protocol default can also be set by importing and loading
2419 `gsoap/import/soap12.h`:
2420 
2421  #import "soap12.h"
2422 
2423 
2424 Non-SOAP XML serialization {#non-soap}
2425 --------------------------
2426 
2427 You can serialize data that is stored on the heap, on the stack (locals), and
2428 static data as long as the serializable (i.e. non-transient) members are
2429 properly initialized and pointers in the structures are either NULL or point to
2430 valid structures. Deserialized data is put on the heap and managed by the
2431 gSOAP engine context `struct soap`, see also [Memory management](#memory).
2432 
2433 You can read and write XML directly to a file or stream with the serializing
2434 [Operations on classes and structs](#toxsd9-11).
2435 
2436 To define and use XML Web service client and service operations, we can declare
2437 these operations in our gSOAP header file for soapcpp2 as functions that
2438 soapcpp2 will translate in client-side service invocation calls and server-side
2439 service operation dispatchers. These functions are auto-generated by wsdl2h
2440 from WSDLs. Note that XSDs do not include service definitions.
2441 
2442 The REST operations POST, GET, and PUT are declared with gSOAP directives in
2443 the gSOAP header file for soapcpp2. For example, a REST POST operation is
2444 declared as follows:
2445 
2446  //gsoap ns service namespace: urn:DB
2447  //gsoap ns service method-protocol: DBupdate POST
2448  int ns__DBupdate(...);
2449 
2450 There is no SOAP Envelope and no SOAP Body in the payload for `DBupdate`. Also
2451 the XML serialization rules are identical to SOAP document/literal. The XML
2452 payload only has the operation name as an element with its parameters
2453 serialized as subelements:
2454 
2455  <ns:DBupdate xmln:ns="urn:DB" ...>
2456  ...
2457  </ns:DBupdate>
2458 
2459 To force id-ref serialization with REST similar to SOAP 1.2 multi-reference
2460 encoding, use the `SOAP_XML_GRAPH` flag to initialize the gSOAP engine context.
2461 The XML serialization includes id and ref attributes for multi-referenced
2462 elements as follows:
2463 
2464  <ns:DBupdate xmln:ns="urn:DB" ...>
2465  <records>
2466  <item>
2467  <name id="_1">Joe</name>
2468  <SSN>1234567890</SSN>
2469  </item>
2470  <item>
2471  <name>Jane</name>
2472  <SSN>1987654320</SSN>
2473  </item>
2474  <item>
2475  <name ref="_1"/>
2476  <SSN>2345678901</SSN>
2477  </item>
2478  </records>
2479  </ns:DBupdate>
2480 
2481 
2482 Memory management {#memory}
2483 =================
2484 
2485 Memory management with the `soap` context enables us to allocate data in
2486 context-managed heap space that can be collectively deleted. All deserialized
2487 data is placed on the context-managed heap by the gSOAP engine.
2488 
2489 
2490 Memory management in C {#memory1}
2491 ----------------------
2492 
2493 In C (wsdl2h option `-c` and soapcpp2 option `-c`), the gSOAP engine allocates
2494 data on a context-managed heap with:
2495 
2496 - `void *soap_malloc(struct soap*, size_t len)`.
2497 
2498 The `soap_malloc` function is a wrapper around `malloc`, but which also allows
2499 the `struct soap` context to track all heap allocations for collective deletion
2500 with `soap_end(soap)`:
2501 
2502  #include "soapH.h"
2503  #include "ns.nsmap"
2504  ...
2505  struct soap *soap = soap_new(); // new context
2506  ...
2507  struct ns__record *record = soap_malloc(soap, sizeof(struct ns__record));
2508  soap_default_ns__record(soap, record);
2509  ...
2510  soap_destroy(soap); // only for C++, see section on C++ below
2511  soap_end(soap); // delete record and all other heap allocations
2512  soap_free(soap); // delete context
2513 
2514 The soapcpp2 auto-generated deserializers in C use `soap_malloc` to allocate
2515 and populate deserialized structures, which are managed by the context for
2516 collective deletion.
2517 
2518 To make `char*` and `wchar_t*` string copies to the context-managed heap, we
2519 can use the functions:
2520 
2521 - `char *soap_strdup(struct soap*, const char*)` and
2522 - `wchar_t *soap_wstrdup(struct soap*, const wchar_t*)`.
2523 
2524 We use the soapcpp2 auto-generated `soap_dup_T` functions to duplicate data
2525 into another context (this requires soapcpp2 option `-Ec` to generate), here
2526 shown for C with the second argument `dst` NULL because we want to allocate a
2527 new managed structure:
2528 
2529  struct soap *other_soap = soap_new(); // another context
2530  struct ns__record *other_record = soap_dup_ns__record(other_soap, NULL, record);
2531  ...
2532  soap_destroy(other_soap); // only for C++, see section on C++ below
2533  soap_end(other_soap); // delete other_record and all of its deep data
2534  soap_free(other_soap); // delete context
2535 
2536 Note that the only reason to use another context and not to use the primary
2537 context is when the primary context must be destroyed together with all of the
2538 objects it manages while some of the objects must be kept alive. If the objects
2539 that are kept alive contain deep cycles then this is the only option we have,
2540 because deep copy with a managing context detects and preserves these
2541 cycles unless the `SOAP_XML_TREE` flag is used with the context:
2542 
2543  struct soap *other_soap = soap_new1(SOAP_XML_TREE); // another context
2544  struct ns__record *other_record = soap_dup_ns__record(other_soap, NULL, record);
2545 
2546 The resulting deep copy will be a full copy of the source data structure as a
2547 tree without co-referenced data (i.e. no digraph) and without cycles. Cycles
2548 are pruned and (one of the) pointers that forms a cycle is repaced by NULL.
2549 
2550 We can also deep copy into unmanaged space and use the auto-generated
2551 `soap_del_T()` function (requires soapcpp2 option `-Ed` to generate) to delete
2552 it later, but we MUST NOT do this for any data that we suspect has deep cycles:
2553 
2554  struct ns__record *other_record = soap_dup_ns__record(NULL, NULL, record);
2555  ...
2556  soap_del_ns__record(other_record); // deep delete record data members
2557  free(other_record); // delete the record
2558 
2559 Cycles in the data structure will lead to non-termination when making unmanaged
2560 deep copies. Consider for example:
2561 
2562  struct ns__record
2563  {
2564  const char *name;
2565  uint64_t SSN;
2566  ns__record *spouse;
2567  };
2568 
2569 Our code to populate a structure with a mutual spouse relationship:
2570 
2571  struct soap *soap = soap_new();
2572  ...
2573  struct ns__record pers1, pers2;
2574  soap_default_ns__record(soap, &pers1);
2575  soap_default_ns__record(soap, &pers2);
2576  pers1.name = "Joe"; // OK to serialize static data
2577  pers1.SSN = 1234567890;
2578  pers1.spouse = &pers2;
2579  pers2.name = soap_strdup(soap, "Jane"); // allocates and copies a string
2580  pers2.SSN = 1987654320;
2581  pers2.spouse = &pers1;
2582  ...
2583  struct ns__record *pers3 = soap_dup_ns__record(NULL, NULL, &pers1); // BAD
2584  struct ns__record *pers4 = soap_dup_ns__record(soap, NULL, &pers1); // OK
2585  soap_set_mode(soap, SOAP_XML_TREE);
2586  struct ns__record *pers5 = soap_dup_ns__record(soap, NULL, &pers1); // OK
2587 
2588 As we can see, the gSOAP serializer can serialize any heap, stack, or static
2589 allocated data, such as in our code above. So we can serialize the
2590 stack-allocated `pers1` record as follows:
2591 
2592  soap->sendfd = fopen("record.xml", "w");
2593  soap_set_mode(soap, SOAP_XML_GRAPH); // support id-ref w/o requiring SOAP
2594  soap_clr_mode(soap, SOAP_XML_TREE); // if set, clear
2595  soap_write_ns__record(soap, &pers1);
2596  fclose(soap->sendfd);
2597  soap->sendfd = NULL;
2598 
2599 which produces an XML document record.xml that is similar to:
2600 
2601  <ns:record xmlns:ns="urn:types" id="Joe">
2602  <name>Joe</name>
2603  <SSN>1234567890</SSN>
2604  <spouse id="Jane">
2605  <name>Jane</name>
2606  <SSN>1987654320</SSN>
2607  <spouse ref="#Joe"/>
2608  </spouse>
2609  </ns:record>
2610 
2611 Deserialization of an XML document with a SOAP 1.1/1.2 encoded id-ref graph
2612 leads to the same non-termination problem when we later try to copy the data
2613 into unmanaged space:
2614 
2615  struct soap *soap = soap_new1(SOAP_XML_GRAPH); // support id-ref w/o SOAP
2616  ...
2617  struct ns__record pers1;
2618  soap->recvfd = fopen("record.xml", "r");
2619  soap_read_ns__record(soap, &pers1);
2620  fclose(soap->recvfd);
2621  soap->recvfd = NULL;
2622  ...
2623  struct ns__record *pers3 = soap_dup_ns__record(NULL, NULL, &pers1); // BAD
2624  struct ns__record *pers4 = soap_dup_ns__record(soap, NULL, &pers1); // OK
2625  soap_set_mode(soap, SOAP_XML_TREE);
2626  struct ns__record *pers5 = soap_dup_ns__record(soap, NULL, &pers1); // OK
2627 
2628 Copying data with `soap_dup_T(soap)` into managed space is always safe. Copying
2629 into unmanaged space requires diligence. But deleting unmanaged data is easy
2630 with `soap_del_T()`.
2631 
2632 We can also use `soap_del_T()` to delete structures that we created in C, but
2633 only if these structures are created with `malloc` and do NOT contain pointers
2634 to stack and static data.
2635 
2636 
2637 Memory management in C++ {#memory2}
2638 ------------------------
2639 
2640 In C++, the gSOAP engine allocates data on a managed heap using a combination
2641 of `void *soap_malloc(struct soap*, size_t len)` and `soap_new_T()`, where `T`
2642 is the name of a class, struct, or class template (container or smart pointer).
2643 Heap allocation is tracked by the `struct soap` context for collective
2644 deletion with `soap_destroy(soap)` and `soap_end(soap)`.
2645 
2646 Only structs, classes, and class templates are allocated with `new` via
2647 `soap_new_T(struct soap*)` and mass-deleted with `soap_destroy(soap)`.
2648 
2649 There are four variations of `soap_new_T` for class/struct/template type `T`
2650 that soapcpp2 auto-generates to create instances on a context-managed heap:
2651 
2652 - `T * soap_new_T(struct soap*)` returns a new instance of `T` with default data
2653  member initializations that are set with the soapcpp2 auto-generated `void
2654  T::soap_default(struct soap*)` method), but ONLY IF the soapcpp2
2655  auto-generated default constructor is used that invokes `soap_default()` and
2656  was not replaced by a user-defined default constructor.
2657 
2658 - `T * soap_new_T(struct soap*, int n)` returns an array of `n` new instances of
2659  `T`. Similar to the above, instances are initialized.
2660 
2661 - `T * soap_new_req_T(struct soap*, ...)` returns a new instance of `T` and sets
2662  the required data members to the values specified in `...`. The required data
2663  members are those with nonzero minOccurs, see the subsections on
2664  [(Smart) pointer members and their occurrence constraints](#toxsd9-6) and
2665  [Container members and their occurrence constraints](#toxsd9-7).
2666 
2667 - `T * soap_new_set_T(struct soap*, ...)` returns a new instance of `T` and sets
2668  the public/serializable data members to the values specified in `...`.
2669 
2670 The above functions can be invoked with a NULL `soap` context, but we will be
2671 responsible to use `delete T` to remove this instance from the unmanaged heap.
2672 
2673 Primitive types and arrays of these are allocated with `soap_malloc` by the
2674 gSOAP engine. As we stated above, all types except for classes, structs, class
2675 templates (containers and smart pointers) are allocated with `soap_malloc` for
2676 reasons of efficiency.
2677 
2678 We can use a C++ template to simplify the managed allocation and initialization
2679 of primitive values as follows (this is for primitive types only, because we
2680 should allocate structs and classes with `soap_new_T`):
2681 
2682  template<class T>
2683  T * soap_make(struct soap *soap, T val)
2684  {
2685  T *p = (T*)soap_malloc(soap, sizeof(T));
2686  if (p) // out of memory? Can also guard with assert(p != NULL) or throw an error
2687  *p = val;
2688  return p;
2689  }
2690 
2691 For example, assuming we have the following class:
2692 
2693  class ns__record
2694  {
2695  public:
2696  std::string name; // required name
2697  uint64_t *SSN; // optional SSN
2698  ns__record *spouse; // optional spouse
2699  };
2700 
2701 We can instantiate a record by using the auto-generated
2702 `soap_new_set_ns__record` and our `soap_make` to create a SSN value on the
2703 managed heap:
2704 
2705  soap *soap = soap_new(); // new context
2706  ...
2707  ns__record *record = soap_new_set_ns__record(
2708  soap,
2709  "Joe",
2710  soap_make<uint64_t>(soap, 1234567890LL),
2711  NULL);
2712  ...
2713  soap_destroy(soap); // delete record and all other managed instances
2714  soap_end(soap); // delete managed soap_malloc'ed heap data
2715  soap_free(soap); // delete context
2716 
2717 Note however that the gSOAP serializer can serialize any heap, stack, or static
2718 allocated data. So we can also create a new record as follows:
2719 
2720  uint64_t SSN = 1234567890LL;
2721  ns__record *record = soap_new_set_ns__record(soap, "Joe", &SSN, NULL);
2722 
2723 which will be fine to serialize this record as long as the local `SSN`
2724 stack-allocated value remains in scope when invoking the serializer and/or
2725 using `record`. It does not matter if `soap_destroy` and `soap_end` are called
2726 beyond the scope of `SSN`.
2727 
2728 To facilitate our class methods to access the managing context, we can add a
2729 soap context pointer to a class/struct:
2730 
2731  class ns__record
2732  {
2733  ...
2734  void create_more(); // needs a context to create more internal data
2735  protected:
2736  struct soap *soap; // the context that manages this instance, or NULL
2737  };
2738 
2739 The context is set when invoking `soap_new_T` (and similar) with a non-NULL
2740 context argument.
2741 
2742 We use the soapcpp2 auto-generated `soap_dup_T` functions to duplicate data
2743 into another context (this requires soapcpp2 option `-Ec` to generate), here
2744 shown for C++ with the second argument `dst` NULL because we want to allocate a
2745 new managed object:
2746 
2747  soap *other_soap = soap_new(); // another context
2748  ns__record *other_record = soap_dup_ns__record(other_soap, NULL, record);
2749  ...
2750  soap_destroy(other_soap); // delete record and other managed instances
2751  soap_end(other_soap); // delete other data (the SSNs on the heap)
2752  soap_free(other_soap); // delete context
2753 
2754 To duplicate base and derived instances when a base class pointer or reference
2755 is provided, use the auto-generated method `T * T::soap_dup(struct soap*)`:
2756 
2757  soap *other_soap = soap_new(); // another context
2758  ns__record *other_record = record->soap_dup(other_soap);
2759  ...
2760  soap_destroy(other_soap); // delete record and other managed instances
2761  soap_end(other_soap); // delete other data (the SSNs on the heap)
2762  soap_free(other_soap); // delete context
2763 
2764 Note that the only reason to use another context and not to use the primary
2765 context is when the primary context must be destroyed together with all of the
2766 objects it manages while some of the objects must be kept alive. If the objects
2767 that are kept alive contain deep cycles then this is the only option we have,
2768 because deep copy with a managing context detects and preserves these
2769 cycles unless the `SOAP_XML_TREE` flag is used with the context:
2770 
2771  soap *other_soap = soap_new1(SOAP_XML_TREE); // another context
2772  ns__record *other_record = record->soap_dup(other_soap); // deep tree copy
2773 
2774 The resulting deep copy will be a full copy of the source data structure as a
2775 tree without co-referenced data (i.e. no digraph) and without cycles. Cycles
2776 are pruned and (one of the) pointers that forms a cycle is repaced by NULL.
2777 
2778 We can also deep copy into unmanaged space and use the auto-generated
2779 `soap_del_T()` function or the `T::soap_del()` method (requires soapcpp2 option
2780 `-Ed` to generate) to delete it later, but we MUST NOT do this for any data
2781 that we suspect has deep cycles:
2782 
2783  ns__record *other_record = record->soap_dup(NULL);
2784  ...
2785  other_record->soap_del(); // deep delete record data members
2786  delete other_record; // delete the record
2787 
2788 Cycles in the data structure will lead to non-termination when making unmanaged
2789 deep copies. Consider for example:
2790 
2791  class ns__record
2792  {
2793  const char *name;
2794  uint64_t SSN;
2795  ns__record *spouse;
2796  };
2797 
2798 Our code to populate a structure with a mutual spouse relationship:
2799 
2800  soap *soap = soap_new();
2801  ...
2802  ns__record pers1, pers2;
2803  pers1.name = "Joe";
2804  pers1.SSN = 1234567890;
2805  pers1.spouse = &pers2;
2806  pers2.name = "Jane";
2807  pers2.SSN = 1987654320;
2808  pers2.spouse = &pers1;
2809  ...
2810  ns__record *pers3 = soap_dup_ns__record(NULL, NULL, &pers1); // BAD
2811  ns__record *pers4 = soap_dup_ns__record(soap, NULL, &pers1); // OK
2812  soap_set_mode(soap, SOAP_XML_TREE);
2813  ns__record *pers5 = soap_dup_ns__record(soap, NULL, &pers1); // OK
2814 
2815 Note that the gSOAP serializer can serialize any heap, stack, or static
2816 allocated data, such as in our code above. So we can serialize the
2817 stack-allocated `pers1` record as follows:
2818 
2819  soap->sendfd = fopen("record.xml", "w");
2820  soap_set_mode(soap, SOAP_XML_GRAPH); // support id-ref w/o requiring SOAP
2821  soap_clr_mode(soap, SOAP_XML_TREE); // if set, clear
2822  soap_write_ns__record(soap, &pers1);
2823  fclose(soap->sendfd);
2824  soap->sendfd = NULL;
2825 
2826 which produces an XML document record.xml that is similar to:
2827 
2828  <ns:record xmlns:ns="urn:types" id="Joe">
2829  <name>Joe</name>
2830  <SSN>1234567890</SSN>
2831  <spouse id="Jane">
2832  <name>Jane</name>
2833  <SSN>1987654320</SSN>
2834  <spouse ref="#Joe"/>
2835  </spouse>
2836  </ns:record>
2837 
2838 Deserialization of an XML document with a SOAP 1.1/1.2 encoded id-ref graph
2839 leads to the same non-termination problem when we later try to copy the data
2840 into unmanaged space:
2841 
2842  soap *soap = soap_new1(SOAP_XML_GRAPH); // support id-ref w/o SOAP
2843  ...
2844  ns__record pers1;
2845  soap->recvfd = fopen("record.xml", "r");
2846  soap_read_ns__record(soap, &pers1);
2847  fclose(soap->recvfd);
2848  soap->recvfd = NULL;
2849  ...
2850  ns__record *pers3 = soap_dup_ns__record(NULL, NULL, &pers1); // BAD
2851  ns__record *pers4 = soap_dup_ns__record(soap, NULL, &pers1); // OK
2852  soap_set_mode(soap, SOAP_XML_TREE);
2853  ns__record *pers5 = soap_dup_ns__record(soap, NULL, &pers1); // OK
2854 
2855 Copying data with `soap_dup_T(soap)` into managed space is always safe. Copying
2856 into unmanaged space requires diligence. But deleting unmanaged data is easy
2857 with `soap_del_T()`.
2858 
2859 We can also use `soap_del_T()` to delete structures in C++, but only if these
2860 structures are created with `new` (and `new []` for arrays when applicable) for
2861 classes, structs, and class templates and with `malloc` for anything else, and
2862 the structures do NOT contain pointers to stack and static data.
2863 
2864 Features and limitations {#features}
2865 ========================
2866 
2867 In general, to use the generated code:
2868 
2869 - Make sure to `#include "soapH.h"` in your code and also define a namespace
2870  table or `#include "ns.nsmap"` with the generated table, where `ns` is the
2871  namespace prefix for services.
2872 
2873 - Use soapcpp2 option -j (C++ only) to generate C++ proxy and service objects.
2874  The auto-generated files include documented inferfaces. Compile with
2875  soapC.cpp and link with -lgsoap++, or alternatively compile stdsoap2.cpp.
2876 
2877 - Without soapcpp2 option -j: client-side uses the auto-generated
2878  soapClient.cpp and soapC.cpp (or C versions of those). Compile and link with
2879  -lgsoap++ (-lgsoap for C), or alternatively compile stdsoap2.cpp
2880  (stdsoap2.c for C).
2881 
2882 - Without soapcpp2 option -j: server-side uses the auto-generated
2883  soapServer.cpp and soapC.cpp (or C versions of those). Compile and link with
2884  -lgsoap++ (-lgsoap for C), or alternatively compile stdsoap2.cpp (stdsoap2.c
2885  for C).
2886 
2887 - Use `soap_new()` or `soap_new1(int flags)` to allocate and initialize a
2888  heap-allocated context with or without flags. Delete this context with
2889  `soap_free(struct soap*)`, but only after `soap_destroy(struct soap*)` and
2890  `soap_end(struct soap*)`.
2891 
2892 - Use `soap_init(struct *soap)` or `soap_init1(struct soap*, int flags)` to
2893  initialize a stack-allocated context with or without flags. End the use of
2894  this context with `soap_done(struct soap*)`, but only after
2895  `soap_destroy(struct soap*)` and `soap_end(struct soap*)`.
2896 
2897 There are several context initialization flags and context mode flags to
2898 control XML serialization at runtime:
2899 
2900 - `SOAP_C_UTFSTRING`: enables all `std::string` and `char*` strings to
2901  contain UTF-8 content. This option is recommended.
2902 
2903 - `SOAP_XML_STRICT`: strictly validates XML while deserializing. Should not be
2904  used together with SOAP 1.1/1.2 encoding style of messaging. Use soapcpp2
2905  option `-s` to hard code `SOAP_XML_STRICT` in the generated serializers. Not
2906  recommended with SOAP 1.1/1.2 encoding style messaging.
2907 
2908 - `SOAP_XML_INDENT`: produces indented XML.
2909 
2910 - `SOAP_XML_CANONICAL`: c14n canonocalization, removes unused `xmlns` bindings
2911  and adds them to appropriate places by applying c14n normalization rules.
2912  Should not be used together with SOAP 1.1/1.2 encoding style messaging.
2913 
2914 - `SOAP_XML_TREE`: write tree XML without id-ref, while pruning data structure
2915  cycles to prevent nontermination of the serializer for cyclic structures.
2916 
2917 - `SOAP_XML_GRAPH`: write graph (digraph and cyclic graphs with shared pointers
2918  to objects) using id-ref attributes. That is, XML with SOAP multi-ref
2919  encoded id-ref elements. This is a structure-preserving serialization format,
2920  because co-referenced data and also cyclic relations are accurately represented.
2921 
2922 - `SOAP_XML_DEFAULTNS`: uses xmlns default bindings, assuming that the schema
2923  element form is "qualified" by default (be warned if it is not!).
2924 
2925 - `SOAP_XML_NOTYPE`: removes all xsi:type attribuation. This option is usually
2926  not needed unless the receiver rejects all xs:type attributes. This option
2927  may affect the quality of the deserializer, which relies on xsi:type
2928  attributes to distinguish base class instances from derived class instances
2929  transported in the XML payloads.
2930 
2931 Additional notes with respect to the wsdl2h and soapcpp2 tools:
2932 
2933 - Nested classes, structs, and unions in a gSOAP header file are unnested by
2934  soapcpp2.
2935 
2936 - Use `#import "file.h"` instead of `#include` to import other header files in
2937  a gSOAP header file for soapcpp2. The `#include` and `#define` directives are
2938  accepted, but are moved to the very start of the generated code for the C/C++
2939  compiler to include before all generated definitions. You should use
2940  `#include` in combinatio with "volatile" types and to ensure transient
2941  (incomplete) types are declared when these are used in the gSOAP header file.
2942 
2943 - To remove any SOAP-specific bindings, use soapcpp2 option `-0`.
2944 
2945 - A gSOAP header file for soapcpp2 should not include any code statements, only
2946  data type declarations. This includes constructor initialization lists that are
2947  not permitted. Use member initializations instead.
2948 
2949 - C++ namespaces are supported. Use wsdl2h option `-qname`. Or add a `namespace
2950  name { ... }` to the header file, but the `{ ... }` MUST cover the entire
2951  header file content from begin to end.
2952 
2953 - Optional DOM support can be used to store mixed content or literal XML
2954  content. Otherwise, mixed content may be lost. Use wsdl2h option `-d` for
2955  DOM support and compile and link with `dom.c` or `dom.cpp`.
2956 
2957 
2958 Removing SOAP namespaces from XML payloads {#nsmap}
2959 ==========================================
2960 
2961 The soapcpp2 tool generates a `.nsmap` file that includes two bindings for SOAP
2962 namespaces. We can remove all SOAP namespaces (and SOAP processing logic) with
2963 soapcpp2 option `-0` or by simply setting the two entries to NULL:
2964 
2965  struct Namespace namespaces[] =
2966  {
2967  {"SOAP-ENV", NULL, NULL, NULL},
2968  {"SOAP-ENC", NULL, NULL, NULL},
2969  ...
2970 
2971 Note that once the `.nsmap` is generated, we can copy-paste the content into
2972 our project code. However, if we rerun wsdl2h on updated WSDL/XSD files or
2973 `typemap.dat` declarations then we need to use the updated table.
2974 
2975 In cases that no XML namespaces are used at all, for example with
2976 [XML-RPC](www.genivia.com/doc/xml-rpc-json/html), you may use an empty
2977 namespace table:
2978 
2979  struct Namespace namespaces[] = {{NULL,NULL,NULL,NULL}};
2980 
2981 However, beware that any built-in xsi attributes that are rendered will lack
2982 the proper namespace binding. At least we suggest to use `SOAP_XML_NOTYPE` for
2983 this reason.
2984 
2985 Examples {#examples}
2986 ========
2987 
2988 Select the project files below to peruse the source code examples.
2989 
2990 
2991 Source files
2992 ------------
2993 
2994 - `address.xsd` Address book schema
2995 - `address.cpp` Address book app (reads/writes address.xml file)
2996 - `addresstypemap.dat` Schema namespace prefix name preference for wsdl2h
2997 - `graph.h` Graph data binding (tree, digraph, cyclic graph)
2998 - `graph.cpp` Test graph serialization as tree, digraph, and cyclic
2999 
3000 
3001 Generated files
3002 ---------------
3003 
3004 - `address.h` gSOAP-specific data binding definitions from address.xsd
3005 - `addressStub.h` C++ data binding definitions
3006 - `addressH.h` Serializers
3007 - `addressC.cpp` Serializers
3008 - `address.xml` Address book data generated by address app
3009 - `graphStub.h` C++ data binding definitions
3010 - `graphH.h` Serializers
3011 - `graphC.cpp` Serializers
3012 - `g.xsd` XSD schema with `g:Graph` complexType
3013 - `g.nsmap` xmlns bindings namespace mapping table
3014 
3015 
3016 Build steps
3017 -----------
3018 
3019 Building the AddressBook example:
3020 
3021  wsdl2h -g -t addresstypemap.dat address.xsd
3022  soapcpp2 -0 -CS -I../../import -p address address.h
3023  c++ -I../.. address.cpp addressC.cpp -o address -lgsoap++
3024 
3025 Option `-g` produces bindings for global (root) elements in addition to types.
3026 In this case the root element `a:address-book` is bound to `_a__address_book`.
3027 The complexType `a:address` is bound to class `a__address`, which is also the
3028 type of `_a__address_book`. This option is not required, but allows you to use
3029 global element tag names when referring to their serializers, instead of their
3030 type name. Option `-0` removes the SOAP protocol. Options `-C` and `-S`
3031 removes client and server code generation. Option `-p` renames the output
3032 `soap` files to `address` files.
3033 
3034 See the `address.cpp` implementation and [Related Pages](pages.html).
3035 
3036 The `addresstypemap.dat` file specifies the XML namespace prefix for the
3037 bindings:
3038 
3039  # Bind the address book schema namespace to prefix 'a'
3040 
3041  a = "urn:address-book-example"
3042 
3043  # By default the xsd:dateTime schema type is translated to time_t
3044  # To map xsd:dateTime to struct tm, enable the following line:
3045 
3046  # xsd__dateTime = #import "../../custom/struct_tm.h"
3047 
3048  # ... and compile/link with custom/struct_tm.c
3049 
3050 The DOB field is a xsd:dateTime, which is bound to `time_t` by default. To
3051 change this to `struct tm`, enable the import of the `xsd__dateTime` custom
3052 serializer by uncommenting the definition of `xsd__dateTime` in
3053 `addresstypemap.dat`. Then change `soap_dateTime2s` to `soap_xsd__dateTime2s`
3054 in the code.
3055 
3056 Building the graph serialization example:
3057 
3058  soapcpp2 -CS -I../../import -p graph graph.h
3059  c++ -I../.. graph.cpp graphC.cpp -o graph -lgsoap++
3060 
3061 To compile without using the `libgsoap++` library: simply compile
3062 `stdsoap2.cpp` together with the above.
3063 
3064 
3065 Usage
3066 -----
3067 
3068 To execute the AddressBook example:
3069 
3070  ./address
3071 
3072 To execute the Graph serialization example:
3073 
3074  ./graph
3075