When you start working with the Web services space, you quickly realize that so much in this space resolves completely around SOAP and WSDL. SOAP, or Simple Object Access Protocol, is the language that Web services speak to transmit messages over the wire. WSDL, or Web Services Description Language, is the XML structure used to describe the SOAP messages involved in the request/response process.
This chapter investigates both of these technologies and how to use them to your advantage in the applications you are building today. It reviews the basics of SOAP and WSDL, as well as how you can go about extending both these technologies using various tools and technologies that are at your disposal in the industry today.
SOAP is an XML-based technology. It is an agreed-upon standard of XML markup used in the transmission of messages across a corporate network or the public Internet. SOAP is the most important pillar in the Web services model.
The proposed Web services model is presented in Figure 20-1 and involves a process of search, discovery, definition, and communication. The first three steps in this process are one-time steps, but these steps are required to get to where you really want to go — the communication step. This step is the step that deals with SOAP. Web service communication is done through the use of SOAP.
As you look over this diagram, notice that not every step mentioned is required to participate in the Web services world. Also, in ...