Used for
The SOAP frameworks allows an application to send and receive Soap messages and to integrate them with the rest of the application. Most frameworks can be extended to provide additional services like reliable messaging, security etc.
Function
To send a message the payload has to be assembled into a bona-fide SOAP-message, the recipient has to be located and the assembled message physically forwarded to the recipient.
The message assembly is handled by one or more of the frameworks data bindings which typically accept the payload as a data structure in the programing language of the application. When the payload is assembled into a message, the recipient is located using the ws-address endpoint address provided and the message is sent using a transport. HTTP is probably the most common transport but others like SMTP can be used.