Web services (sometimes called application services) are services (usually including some combination of programming and data, but possibly including human resources as well) that are made available from a business’s Web server for Web users or other Web-connected programs. Providers of Web services are generally known as application service providers. Web services range from such major services as storage management, enterprise resource planning (ERP) and customer relationship management ( CRM ) down to much more limited services such as the furnishing of a stock quote and the checking of bids for an auction item. The accelerating creation and availability of these services is a major Web trend.
Users can access some Web services through a peer-to-peer arrangement rather than by going to a central server. Some services can communicate with other services and this exchange of procedures and data is generally enabled by a class of software known as middleware . Services previously possible only with the older standardized service known as Electronic Data Interchange ( EDI ) increasingly are likely to become Web services.
Besides the standardization and wide availability to users and businesses of the Internet itself, Web services are also increasingly enabled by the use of the Extensible Markup Language ( XML ) as a means of standardizing data formats and exchanging data. XML is the foundation for the Web Services Description Language ( WSDL ).
As Web services proliferate, concerns include the overall demands on network bandwidth and, for any particular service, the effect on performance as demands for that service rise. A number of new products have emerged that enable software developers to create or modify existing applications that can be “published” (made known and potentially accessible) as Web services.