Messages need to be bound to a WSDL document. If the payload is a SOAP message, then the soap:binding element is included within the WSDL binding element. The soap:binding element takes two attributes, transport and style.

In the syntax to include the soap:binding element within the WSDL binding element, the transport attribute indicates the transport protocol, such as HTTP or SMTP for each message, and the style attribute specifies the format of the message. It can take either of the two formats, RPC or document.

If the value of the style attribute is RPC, the request and response messages are exchanged in the form of function calls. If the value of the style attribute is document, then request and response messages consist of XML documents.

In the code snippet, the URL indicates that the transport protocol is HTTP and the format of the message is RPC.