Lotus Instant Messaging/ Web Conferencing ... - IBM Redbooks

On the server side, a Web server and, for Java-based Web services, a servletengine is all that is required. On the client side, a programming language withXML and HTTP client support is all that is needed. It is possible to create a Webservice from an existing application without writing a single line of code, as 4.4,“Creating the UserStatus Web service” on page 97 illustrates.Web services are self-describing: neither the client nor the server needs to knowanything besides the format and content of the request and response messages.How the actual service works at the application level is irrelevant to the client,and how the client generates the request and what it does with the response isirrelevant to the server.You can generate an XML-based description of the Web service that explainshow it can be accessed. The Web Services Description Language (WSDL)allows Web services-enabled systems to tell each other what capabilities theyhave, and how to programmatically interact with them. Once a Web service isdescribed in WSDL, developers can create Web service clients to interact with it.You can also publish the Web service to a directory of Web services so that itcan be discovered by other Web service clients. Universal Description,Discovery, and Integration (UDDI) is an XML-based directory or registry of Webservices. UDDI provides a place for you to list your Web service and to find outabout others. The combination of WSDL and UDDI means Web servicedescription and discovery can be automated, allowing clients to bind todynamically-discovered services.With SOAP, you can send a request to another application, for example, to returnthe status of an item from a shipping system. You get the results back in a setformat that you can then process. To publish the shipping system as a Webservice, you register the application with an application server that supports theSOAP protocol (which runs as an HTTP extension). You can generate a WSDLdescription of the application that explains how it can be accessed. You can thenpublish that description to a UDDI directory.This section has been deliberately brief: we encourage you to gain a morein-depth understanding of Web services by consulting the Redbooks WebSphereVersion 5 Web Services Handbook, SG24-6891 and Web Services Wizardry withWebSphere Studio Application Developer, SG24-6292.4.2 Sametime Web servicesA Sametime Web service is simply a Web service layer that exposes thefunctionality of a Sametime application. Once you expose a Sametimeapplication as a Web service, you give any client capable of submitting an HTTPChapter 4. Web services 85