Web Services Building Blocks: WSDL and UDDI

Chapter 16

Web Services Building Blocks: WSDL and UDDI

IN THIS CHAPTER

•        Introduction to WSDL

• Basic WSDL Syntax

• SOAP Binding

• WSDL Implementations

•        Introduction to UDDI

• The UDDI API

•        Vendor Implementations

•        The Future of UDDI

The Web Services Description Language (WSDL) and Universal Description, Discovery, and Integration (UDDI), along with SOAP, form the essential building blocks for Web Services. Each one, taken separately, serves its own particular purposes, but taken together, they provide the foundation for the just-in-time, Service-Oriented Architecture detailed in Chapter 14, “Architecting Web Services.”

WSDL (often pronounced wiz-dill) is an XML-based format for describing Web Services. It describes which operations Web Services can execute and the format of the messages Web Services can send and receive. UDDI (pronounced, unfortunately, U-D-D-I ) is a pro-tocol that describes a standard way of setting up registries of Web Services, along with the methods of querying such registries for information about the Web Services they contain. Each UDDI registry’s response to a query contains a WSDL message, which instructs the requester on how to interact with the desired Web Service. (Refer to Figure 14.2 in Chapter 14 for a picture of how these operations fit together.)

In this chapter, you will learn

   The basics of WSDL syntax

   How WSDL and SOAP work together

   How to use popular WSDL implementations

   The elements of UDDI and how they work together

   How to use the UDDI API

   How to use UDDI implementations to interact with existing UDDI registries

   The future of UDDI