The idea behind web services is to expose an application as a service for clients over the web independently of the application and clients' execution environments. The application may be fine grained, such as a mathematical calculation, or coarse grained, such as processing an order. Interoperability is an important goal of web services and all leading technology providers, including Microsoft, have subscribed to web services standards. This means a C# client running under .NET can invoke a web service implemented as a Java EJB in a Java EE environment and vice-versa. The interoperability goal of web services means that such services are more loosely coupled than EJBs.

There are two main organizations which develop web service standards: The World Wide Web Consortium (W3C) and The Organization for the Advancement of Structured Information Standards (OASIS). The key web service standards are SOAP and WSDL, maintained by W3C, and UDDI maintained by OASIS....