Programming Web Services with SOAP

Chapter 6. Discovering SOAP Services

Once a WSDL description of a web service has been created, a service consumer must be able to locate it in order to be able to use it. This is known as discovery , the topic of this chapter. In particular, we look at the Universal Description, Discovery, and Integration (UDDI) project and the new Web Services Inspection Language.

WSDL provides a service consumer with all the information they need to interact with a service provider. But how can a consumer learn of services to use? The UDDI project is an industry effort to define a searchable registry of services and their descriptions so that consumers can automatically discover the services they need.

UDDI has two parts: a registry of all a web service's metadata (including a pointer to the WSDL description of a service), and a set of WSDL port type definitions for manipulating and searching that registry.

The latest UDDI specification is Version 2.0. In this book, however, we focus completely on Version 1.0. Version 2.0 has not yet been widely implemented and there is very little support available for it.

UDDI is not the only option for service discovery. IBM and Microsoft have recently announced the Web Services Inspection Language (WS-Inspection), an XML-based language that provides an index of all the web services at a given web location.

The first part of this chapter will focus primarily on UDDI. The last half will briefly introduce WS-Inspection and demonstrate its role inService Discovery. ...