Every SOAP package in YAZ is represented as follows:
#include <yaz/soap.h>
typedef struct {
    char *fault_code;
    char *fault_string;
    char *details;
} Z_SOAP_Fault;
typedef struct {
    int no;
    char *ns;
    void *p;
} Z_SOAP_Generic;
#define Z_SOAP_fault 1
#define Z_SOAP_generic 2
#define Z_SOAP_error 3
typedef struct {
    int which;
    union {
        Z_SOAP_Fault   *fault;
        Z_SOAP_Generic *generic;
        Z_SOAP_Fault   *soap_error;
    } u;
    const char *ns;
} Z_SOAP;
      
      The fault and soap_error
      arms represent both a SOAP fault - struct
      Z_SOAP_Fault. Any other generic
        (valid) package is represented by Z_SOAP_Generic.
    
      The ns as part of Z_SOAP
      is the namespace for SOAP itself and reflects the SOAP
      version. For version 1.1 it is
      http://schemas.xmlsoap.org/soap/envelope/,
      for version 1.2 it is
      http://www.w3.org/2001/06/soap-envelope.
    
int z_soap_codec(ODR o, Z_SOAP **pp,
                 char **content_buf, int *content_len,
                 Z_SOAP_Handler *handlers);
    
      The content_buf and content_len
      is XML buffer and length of buffer respectively.
    
      The handlers is a list of SOAP codec
      handlers - one handler for each service namespace. For SRU SOAP, the
      namespace would be http://www.loc.gov/zing/srw/v1.0/.
    
      When decoding, the z_soap_codec
      inspects the XML content
      and tries to match one of the services namespaces of the
      supplied handlers. If there is a match a handler function
      is invoked which decodes that particular SOAP package.
      If successful, the returned Z_SOAP package will be
      of type Z_SOAP_Generic.
      Member no is
      set the offset of handler that matched; ns
      is set to namespace of matching handler; the void pointer
      p is set to the C data structure assocatiated
      with the handler.
    
      When a NULL namespace is met (member ns bwlow),
      that specifies end-of-list.
    
Each handler is defined as follows:
typedef struct {
    char *ns;
    void *client_data;
    Z_SOAP_fun f;
} Z_SOAP_Handler;
      
      The ns is namespace of service associated with
      handler f. client_data
      is user-defined data which is passed to handler.
    
The prototype for a SOAP service handler is:
int handler(ODR o, void * ptr, void **handler_data,
            void *client_data, const char *ns);
      
      The o specifies the mode (decode/encode)
      as usual. The second argument, ptr,
      is a libxml2 tree node pointer (xmlNodePtr)
      and is a pointer to the Body element
      of the SOAP package. The handler_data
      is an opaque pointer to a C definitions associated with the
      SOAP service. client_data is the pointer
      which was set as part of the Z_SOAP_handler.
      Finally, ns the service namespace.