Web services

A web service is an interface that describes a collection of operations that are accessible through the network by using standardized XML messaging.

A web service is described by using a standard, formal XML notation, called a service description, where:
  • The service description includes all the details necessary to interact with the service, including its message formats (that detail the operations), transport protocols, and location.
  • The interface hides the implementation details of the service, allowing it to be used independently of the hardware or software platform on which it is implemented. The interface can also be used independently of the programming language in which it is written.
  • The foundations for web services are standards such as Simple Object Access Protocol (SOAP), the Web Services Description Language (WSDL), and the Universal Description, Discovery, and Integration (UDDI) registry.

Web services are self-contained, self-describing, modular web applications that can be published, located, and invoked across the web. Web services perform functions that can be invoked, ranging from a simple request to complicated business operations. If a web service is deployed and registered, other applications can discover and invoke it.

Web services allow applications to be integrated more rapidly, easily, and less expensively than ever before. Integration focuses on the XML messages that define the services rather than the protocol used to relay these messages. These characteristics are ideal for connecting business functions across the web, both between multiple enterprises and within a single enterprise. They provide a unifying programming model, so that application integration, both inside and outside the enterprise, can be done with a common approach, by using a common infrastructure. The integration and application of web services can be done in an incremental manner, by using existing languages and platforms and by adopting existing applications.