In general, any online service delivered from a website. Since there are countless applications and services that emanate from the Web, such usage of the term is commonplace in articles from non-IT publications. Although the term may also appear in technical journals to refer to any offering on the Web, the astute journalist avoids such usage because "Web services" has a very specific definition (see #2). This is another example of generic names coined for specific technologies (see naming fiascos
When mentioned in the plural ("Web services"), the term often refers to an interface for a service oriented architecture (see SOA
), in which Web-based applications dynamically interact with each other using open standards that include XML, HTTP, UDDI and SOAP. Such applications typically run behind the scenes, one program "talking to" another, server to server or client to server.
Services are registered on the Internet so that applications can search for, find and seamlessly exchange data with them. Both desktop and mobile devices can use them, and if the service is fee based, payment processing is included. For mobile Web services protocols, see DPWS
Web services are also used when large enterprises need to exchange data with their divisions, subsidiaries or clients. In such controlled situations, the data being passed are easily defined. In addition, since Web services use open standards, vendors can supply customers with client-side software no matter what the platform.
CORBA and DCOM
In the past, the Web services style of architecture was occasionally realized within private networks using the industry standard CORBA and Microsoft's DCOM distributed component platforms. See CORBA
It's Just a Protocol
Web services define the format, transport and interface standards, not the meaning of the data exchanged. Before any Web service can be put into operation, there must be industry agreement on the vocabulary and functions each service component must provide (see ebXML
). See Web services protocols
Web Services Protocol Stack
UDDI is used to register and discover the service described in the Web Services Description Language (WSDL). UDDI transactions use SOAP to talk to the UDDI server, and the application uses SOAP to request the service. SOAP messages are delivered by HTTP over TCP/IP. See SOAP