SOAP RPC Representation

The SOAP standard defines how SOAP messages are constructed; however, it doesn't stipulate how such SOAP messages are to be utilized in the pursuit of an extended conversation. One can surmise, however, that the cardinality of the set of possible conversational formats is, well, infinite. So, we won't cover them all here! We'll concentrate our feeble efforts on elucidating a single conversational format, that of the SOAP RPC Representation, in which the client and server's discourse has as its end allowing the client to call a method on the server.

For a client to invoke a remote procedure call on a server using the SOAP RPC representation at minimum the following information is required

1. The URI of ultimate SOAP receiver.
2. The name of the remote procedure to be called.
3. The identities and types of any arguments to be passed to the remote procedure along with the procedure's return value.
4. The conversational format for calling the remote procedure.

Cleansing the dingy windows of perception with a little soap, one can recall that long ago in the stone age of section we looked at WSDL documents. Upon reviewing that section one finds that a WSDL document specifies all the information required to call a remote procedure using the SOAP RPC representation. The service description component specifies the URI of the ultimate SOAP receiver. The porttype description component provides the name of the remote procedure to call. The porttype description component in cahoots with the message description component and the type description component furnish all the data required by the third item above. Finally, the porttype description component nails down the conversational format for calling the remote procedure. WSDL is where it's all at.