3. Directories and repositories

3.1 Dynamic discovery of Web services

The architecture of communications between Web services would be incomplete without a mechanism for dynamic discovery of services at runtime. As with linkers in traditional programming, we can distinguish between a form of static linking between Web services and dynamic discovery, comparable to the "late binding" characteristic of object-oriented programming languages.

In the static link, the client application or Web service knows the URL of the WSDL file describing the remote service. In this case, the client application simply downloads the WSDL document and decodes it, then calls the operations offered by the service in question. In fact, in today's integrated programming environments, this static link is often made...