电信provisioning系统中，常常需要与远程服务器实时交换一些数据，以完成用户的请求。由于简单对象访问协议（Simple Object Access Protocol, SOAP）的流行，许多涉及到第三方的应用，我们一般都比较乐意使用SOAP来开发。不过，由于可能涉及到公司的机密，本系列教程的开发实例尽量采用在网上已经公开的Web Service资源。
前面四节的教程，分别采用了股票信息和天气预报的例子。而这两个实例有一个共同点，SOAP响应消息的数据结构相对简单，只需要按拟定的次序，事先约定返回数据代表的意义，就能够实现无歧义的沟通。这就使得gSOAP能够以字符串数组的形式，定义返回结果，再加上一个整型变量，指示返回结果的个数。
查看一下这两个实例的soapStub.h，可以发现，它们的结果集定义正是这样的：
{
int __sizestring; /* sequence of elements <string> */
char ** string ; /* optional element of type xsd:string */
};
但是，如果服务端返回的是一个相对复杂的结果集，事情就不那么好办了。例如，一个提供外汇汇率的Web Service，服务端会同时返回日元、瑞郎、英镑、欧元、澳元、加元、港币合计七种货币兑换美元的汇率情报，每种汇率情报又包括货币代码、当前汇率、涨跌幅、买入价、卖出价、时间戳等多个子项。显然，这不是一个线性结构，而是一个树形结构，就不能使用ArrayOfString来表示了。
这个案例的End point是：
http://webservice.webxml.com.cn/WebServices/ExchangeRateWebService.asmx
其WSDL是：
http://webservice.webxml.com.cn/WebServices/ExchangeRateWebService.asmx?wsdl
参考前面四节的内容，快速建立其存根程序，不再累述。
我们要实现的API是getExchangeRate，在soapStub.h中搜索，可以发现其返回结果集最终的定义是：
{
char * xsd__schema; /* required element of type xsd:schema */
char * __any;
};
仅仅是两个字符串！于是，最初版本的外汇汇率客户端程序只能这样写：
#include " soapH.h "
#include " ExchangeRateWebServiceSoap12.nsmap "
int conv_charset( const char * dest, const char * src, char * input, size_t ilen, char * output, size_t olen) {
iconv_t conv = iconv_open(dest, src);
if ( conv == (iconv_t) - 1 )
return - 1 ;
memset(output, 0 , olen);
if ( iconv(conv, & input, & ilen, & output, & olen) )
return - 1 ;
iconv_close(conv);
return 0 ;
}
int main( int argc, char ** argv) {
if ( argc != 2 && argc != 3 ) {
printf( " Usage: %s type [end_point]\n " , argv[ 0 ]);
printf( " \ttype = A : all rate\n " );
printf( " \ttype = B : basic rate\n " );
printf( " \ttype = C : cross rate\n " );
exit( - 1 );
}
struct soap soap;
soap_init( & soap);
// don't set is OK
// soap_set_mode(&soap, SOAP_C_UTFSTRING);
struct _ns1__getExchangeRate request;
struct _ns1__getExchangeRateResponse response;
request.theType = argv[ 1 ];
char * endpoint = NULL;
if ( argc == 3 )
endpoint = argv[ 2 ];
if ( soap_call___ns3__getExchangeRate( & soap, endpoint, NULL, & request, & response) == SOAP_OK ) {
printf( " %s\n " , response.getExchangeRateResult -> xsd__schema);
printf( " ----------\n " );
int ilen = strlen(response.getExchangeRateResult -> __any);
int olen = ilen * 2 ;
char * output = ( char * ) malloc( sizeof ( char ) * olen);
conv_charset( " GBK " , " UTF-8 " , response.getExchangeRateResult -> __any, ilen, output, olen);
printf( " %s\n " , output);
free(output);
}
else {
soap_print_fault( & soap, stderr);
}
soap_destroy( & soap);
soap_end( & soap);
soap_done( & soap);
return 0 ;
}
#include <iconv.h> #include "soapH.h" #include "ExchangeRateWebServiceSoap12.nsmap" int conv_charset(const char *dest, const char *src, char *input, size_t ilen, char *output, size_t olen) { iconv_t conv = iconv_open(dest, src); if ( conv == (iconv_t) -1 ) return -1; memset(output, 0, olen); if ( iconv(conv, &input, &ilen, &output, &olen) ) return -1; iconv_close(conv); return 0; } int main(int argc, char **argv) { if ( argc != 2 && argc != 3 ) { printf("Usage: %s type [end_point]\n", argv[0]); printf("\ttype = A : all rate\n"); printf("\ttype = B : basic rate\n"); printf("\ttype = C : cross rate\n"); exit(-1); } struct soap soap; soap_init(&soap); // don't set is OK //soap_set_mode(&soap, SOAP_C_UTFSTRING); struct _ns1__getExchangeRate request; struct _ns1__getExchangeRateResponse response; request.theType = argv[1]; char *endpoint = NULL; if ( argc == 3 ) endpoint = argv[2]; if ( soap_call___ns3__getExchangeRate(&soap, endpoint, NULL, &request, &response) == SOAP_OK ) { printf("%s\n", response.getExchangeRateResult->xsd__schema); printf("----------\n"); int ilen = strlen(response.getExchangeRateResult->__any); int olen = ilen * 2; char *output = (char *) malloc(sizeof(char) * olen); conv_charset("GBK", "UTF-8", response.getExchangeRateResult->__any, ilen, output, olen); printf("%s\n", output); free(output); } else { soap_print_fault(&soap, stderr); } soap_destroy(&soap); soap_end(&soap); soap_done(&soap); return 0; }
其中，xsd__schema没有中文字符，而__any含有中文字符，需要转换成GBK编码，具体可以参考前面两节。
编译执行，输出结果如下图：
可以看出，服务端返回的两个长字符串实际上都是基于XML形式的。gSOAP能够自动帮我们完成的也就到此为止，剩下的需要我们自力更生了。
不过，大家也不用头疼，我们还有另外一个利器——libxml2！网上有很多关于libxml2的教程，所以我也不必多说，只要利用其中几个函数和语句即可。
1. xmlParseMemory，字符串转为XML文档
2. xmlDocGetRootElement，获取XML文档根节点
3. xmlStrcmp，比较XML字符串，与strcmp差不多
4. curr = curr->xmlChildrenNode，XML节点指针指向第一个子节点
5. curr = curr->next，XML节点指针指向下一个兄弟节点
6. xmlNodeGetContent，获取XML节点的内容
7. xmlFreeDoc，释放节点，与free差不多
最终的外汇汇率客户端程序如下：
#include < libxml / parser.h >
#include < libxml / xmlmemory.h >
#include " soapH.h "
#include " ExchangeRateWebServiceSoap12.nsmap "
#define FIELD_LEN 16
int conv_charset( const char * dest, const char * src, char * input, size_t ilen, char * output, size_t olen) {
iconv_t conv = iconv_open(dest, src);
if ( conv == (iconv_t) - 1 )
return - 1 ;
memset(output, 0 , olen);
if ( iconv(conv, & input, & ilen, & output, & olen) )
return - 1 ;
iconv_close(conv);
return 0 ;
}
int main( int argc, char ** argv) {
if ( argc != 2 && argc != 3 ) {
printf( " Usage: %s type [end_point]\n " , argv[ 0 ]);
printf( " \ttype = A : all rate\n " );
printf( " \ttype = B : basic rate\n " );
printf( " \ttype = C : cross rate\n " );
exit( - 1 );
}
struct soap soap;
soap_init( & soap);
// don't set is OK
// soap_set_mode(&soap, SOAP_C_UTFSTRING);
struct _ns1__getExchangeRate request;
struct _ns1__getExchangeRateResponse response;
request.theType = argv[ 1 ];
char * endpoint = NULL;
if ( argc == 3 )
endpoint = argv[ 2 ];
if ( soap_call___ns3__getExchangeRate( & soap, endpoint, NULL, & request, & response) == SOAP_OK ) {
int len = strlen(response.getExchangeRateResult -> __any);
xmlDocPtr pdoc = xmlParseMemory(response.getExchangeRateResult -> __any, len);
xmlNodePtr root = xmlDocGetRootElement(pdoc);
xmlNodePtr curr = root;
while ( xmlStrcmp(curr -> name, ( const xmlChar * ) " getExchangeRate " ) )
curr = curr -> xmlChildrenNode;
for ( curr = curr -> xmlChildrenNode; curr; curr = curr -> next ) {
xmlNodePtr data;
for ( data = curr -> xmlChildrenNode; data; data = data -> next ) {
char ifield[FIELD_LEN];
char ofield[FIELD_LEN];
strcpy(ifield, xmlNodeGetContent(data));
if ( conv_charset( " GBK " , " UTF-8 " , ifield, strlen(ifield), ofield, FIELD_LEN) )
printf( " %s\t%s\n " , data -> name, ifield);
else
printf( " %s\t%s\n " , data -> name, ofield);
}
printf( " \n " );
}
xmlFreeDoc(pdoc);
}
else {
soap_print_fault( & soap, stderr);
}
soap_destroy( & soap);
soap_end( & soap);
soap_done( & soap);
return 0 ;
}
编译时，需要链接libxml2库，同时指定头文件所在路径：
gcc -O2 -o exchange exchange.c soapC.c soapClient.c ../../stdsoap2.c -I../.. -I/usr/include/libxml2 -L../.. -lgsoap -lxml2
执行结果（部分）如下：
-bash-3.2$ ./exchange B
Code JPY
Currency 日元
ClosePrice 87.08
DiffPercent -0.29%
DiffAmount -0.25
OpenPrice 87.5
HighPrice 87.71
LowPrice 87.04
Range 0.77%
BuyPrice 87.08
SellPrice 87.12
ChangeColor Green
DataTime 16:57:54
Code
CHF
Currency 瑞郎
ClosePrice 1.0552
DiffPercent 0.16%
DiffAmount 0.0017
OpenPrice 1.054
HighPrice 1.0552
LowPrice 1.0498
Range 0.51%
BuyPrice 1.0552
SellPrice 1.0556
ChangeColor Red
DataTime 16:57:52
http://blog.csdn.net/yui/archive/2010/07/26/5767494.aspx