Primer on Web Service Protocols

Web services introduce a host of new acronyms and terms. To understand them, it is useful to divide the process of delivering Web services into four layers: representing data, transmitting data, describing Web services, and discovering Web services. The sections below identify the Internet protocols Microsoft uses for each of these layers.

It is important to note that the set of protocols associated with Web services will undoubtedly expand in the future. For example, protocols to handle security and remote management issues are in the works, but haven’t yet been finalized. For this reason, all vendors’ implementations of Web services, whether they be Microsoft’s .NET or IBM’s WebSphere, are still works in progress.

(For further information on Web services standards, see “Web Services Built on Cooperation and Competition” on page 16 of the May 2001 Update.)

Data Representation

Data sent to and received from Web services need to be represented in a mutually recognizable format. Extensible Markup Language (XML) is used for this purpose. XML is a set of rules for creating structured text documents using tags similar to those in HTML. An XML-formatted purchase order might include elements such as “customer name,” “item quantity,” or “price.” Tags (e.g., <CustomerName>) specify where elements begin and end within the document.