Web services
Web services are self-contained, modular applications that one can describe, publish, locate, and invoke over a network.
WebSphere Application Server supports Web services that are developed and implemented based on the Web Services for J2EE specification.
A typical Web services scenario is a business application requesting a service from another existing application. The request is processed through a given Web address using SOAP messages over a HTTP, Java Message Service (JMS) transport or invoked directly as Enterprise JavaBeans (EJB). The service receives the request, processes it, and returns a response. Examples of a simple Web service include weather reports or getting stock quotes. The method call is synchronous, that is, it waits until the result is available. Transaction Web services, supporting quotes, business-to-business (B2B) or business-to-client (B2C) operations include airline reservations and purchase orders.
Web services can include the actual service or the client that accesses the service.
Web services are Web applications that help you be more flexible in your business processes by integrating with applications that otherwise do not communicate. The inner-library loan program at your local library is a good example of the Web services concept and its evolution. The Web service concept existed even before the term; the concept became widely accepted with the creation of the Internet. Before the Internet was created, you visited your library, searched the collections and checked out your books. If you did not find the book that you wanted, the librarian did a search for you by computer or phone and located the book at a nearby library. The librarian ordered the book for you and you picked it up after it was delivered to your local library. By incorporating Web services applications, one can streamline your library visit.
Now, one can search the local library collection and other local libraries at the same time. When other libraries provide your library with a Web service to search their collection (the service might have been provided through UDDI), your results yield their resources. Another Web service application might enable you to check the book out and get it sent to your home. Using Web services applications saves time and provides a convenience for you, as well as freeing the librarian to do other business tasks.
Web services reflect the service-oriented architecture (SOA) approach to programming. This approach is based on the idea of building applications by discovering and implementing network-available services, or by invoking the available applications to accomplish a task. Web services deliver interoperability, for example, Web services applications provide components created in different programming languages to work together as if they were created using the same language. Web services rely on existing transport technologies, such as HTTP, and standard data encoding techniques, such as XML, for invoking the implementation.
The key components of Web services include:
- Web Services Description Language (WSDL)
WSDL is the XML-based file that describes the Web service. The Web service request uses this file to bind to the service.
- SOAP
SOAP is the XML-based protocol that the Web service request uses to invoke the service.
- Universal Description, Discovery and Integration Protocol (UDDI)
UDDI is the registry that hosts the service broker. UDDI is similar to the Yellow Pages in a phone book.
For a more detailed scenario, see Web services scenario: Overview, which tells the story of a fictional online garden supply retailer named Plants by WebSphere, and how this retailer incorporated the Web services concept.
See Also
SOAP
Overview: Online garden retailer Web services scenarios
WSDL
Web Services for J2EE specification
Related Tasks
Using the UDDI Registry
See Also
Web services: Resources for learning