说明
bool 
is_soap_fault ( mixed obj )
   This function is useful when you like to check if the SOAP call failed, but
   don't like to use exceptions. To use it you must create a 
   SoapClient object with the exceptions
   option set to zero or FALSE.
   In this case, the SOAP method will return a special 
   SoapFault object which encapsulates the fault 
   details (faultcode, faultstring, faultactor and faultdetails).
  
   If exceptions is not set then SOAP call will throw
   an exception on error.
   is_soap_fault() checks if the given
   parameter is a SoapFault object.