(1) In general, any online service delivered from a Web site. 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).|
(2) When mentioned in the plural ("Web services"), the term often refers to an interface for a service oriented architecture (SOA), in which Web-based applications dynamically interact with other Web applications using open standards that include XML running over HTTP, UDDI and SOAP. Such applications typically run behind the scenes, one program "talking to" another (server to server). Microsoft's .NET and Sun's Java System (J2EE) are the major development platforms that natively support these standards. See SOA.
Web services have been initially successful in private environments where large enterprises need to exchange data with their divisions and subsidiaries or with partners and clients. In such controlled situations, agreement on the data being passed between Web service components is more easily obtained. In addition, since Web services use open standards, vendors can supply customers with client side software to add to their applications no matter what the platform.
Web services over the public Internet are expected to materialize slowly. Using discovery systems such as UDDI, the goal is to register a service on the Internet, allow an application to search for and find the service and then to seamlessly exchange data with it. If the service is fee based, payment processing could be included. Before global Web services can be put into operation, there must be industry agreement on the functions each service component must provide.
CORBA and DCOM
Web services enable software components to interact with each other around the world. In the past, this has only occasionally been realized within private networks using the industry standard CORBA and Microsoft's DCOM distributed component platforms. However, because Web services use protocols that are open and easier to implement, they have a better chance of being widely implemented.
Although the term became the hot buzzword at the turn of the century, Web services still require cooperation and agreement among people to define business transactions and processes. Web services define only the format, transport and interface standards, not the meaning of the data to be exchanged (see ebXML). See SOA, SOAP, UDDI, Web services protocols and XML.
UDDI is used to register and discover Web services, typically described in WSDL. The UDDI transactions use SOAP to talk to the UDDI server, and then the application uses SOAP to request the Web service. SOAP messages are actually delivered by HTTP and TCP/IP.