“If you want to manage it, you have to define it,” says Luc LeBlanc who chairs the Web Services sub-group at PWGSC. LeBlanc has his work cut out for him; web services is a frequently misunderstood technical term that seems to imply anything that is available over the Web. LeBlanc finds that even the techies often get it wrong. “People believe that a CORBA app is web services, or an HTML applet is web services.”
Here are some of the aspects of web services that are frequently misunderstood:
In the pure sense, web services does not denote services themselves, but the means for publishing and accessing them. Therefore, a program component made available through web services is not a web service, but a service.
Web Services Description Language (WSDL) is a protocol for describing, discovering and calling services. The services themselves can be written on a variety of platforms, but they all use XML tags to describe the transmitted data.
Services can be delivered from a central provider or peer to peer, over an internal network or the Web.
Services are catalogued on central directories where they can be discovered by various applications. The most common directory format is called Universal Description Discovery and Integration (UDDI), but there are others.
Messages are sent through a messaging “envelope” according to the SOAP protocol.
From a big picture scenario, web services fits into Service Oriented Architecture (SOA), a framework within which services exchange data and execute coordinated activity.