Chapter 5. Describing a SOAP Service
Having seen the basic steps in implementing web services, you're now ready to explore technologies that make it easier to use web services that have already been deployed. Specifically, this chapter focuses on the Web Service Description Language (WSDL), which makes possible automated code-generation tools to simplify building clients for existing web services. WSDL also forms an integral component of the discovery process we'll see in Chapter 6.
Describing Web Services
The introduction of web services in Chapter 1 mentioned that one of the key things that sets web services apart from other types of applications is that they can be made self-describing. Here, we describe what that means.
Every application exposes some type of functionality; you invoke that functionality through various types of operations. Those operations require you to provide specific pieces of information. Once the operation is complete, the application may return information back to you. This entire exchange must be conducted using some agreed upon protocol for packaging the information and sending it back and forth. However, most applications typically require you, the developer, to describe how all of this is supposed to happen. The specific details of how a service is implemented become entrenched in the application. If any changes need to be made, the application must be changed and recompiled. These applications are not very flexible.
With web services, though, it is ...
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