The SOAP Model
Web services are an instance of the service-oriented architecture pattern that use SOAP as the (logical) transport mechanism for moving messages between services described by WSDL interfaces. This is a conceptually simple architecture, as shown in Figure 3-1, where SOAP messages are propagated via some underlying transport protocol between Web services.
Figure 3-1. The logical Web services network.
A SOAP message is an XML document whose root element is called the envelope. Within the envelope, there are two child elements called the header and the body. Application payloads are carried in the body, while the information held in ...