Web services overview

Web services overview

A typical Web services scenario is a business application requesting a service from a given URL using Simple Object Access Protocol (SOAP) over a HyperText Transport Protocol (HTTP) or Java Messaging Service (JMS) transport. The service receives the request, processes it, and returns a response. Examples of a simple Web service include weather reports and 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 or purchase orders.

The key components of a Web service are:

Simple Object Access Protocol (SOAP)

WSDL

Universal Description, Discover and Integration Protocol (UDDI)

You can review the Web services client programming model in the Web services for J2EE specification available in the Web services resources topic. The programming model is similar to the EJB client programming model. There is a remote interface that the client uses to interact with the service. A Java Naming and Directory Interface (JNDI) lookup method can locate the service for a client running in a Web container, EJB container, or client container. The client obtains a stub that implements the remote interface and makes calls to invoke operations on the remote service.

There are four locations where a Java Web services client can reside:

As an unmanaged stand-alone Java application.

Within an application client container.

As a Java bean or a servlet running in a Web container that is acting as a client.

As a Java bean or enterprise bean running in an EJB container that is acting as a client.

These topics describe further concepts of Web services:

Web services architecture
This topic discusses how Web service providers, brokers, and requesters interact to provide and run Web services.

Web services operations
This topic discusses the life cycle of a Web service, and the roles played by providers, brokers, and requesters in that cycle.

IBM's AlphaWorks provides tools for creating WSDL files and Simple Object Access Protocol (SOAP) clients and describes working examples. For more information, see http://www.alphaworks.ibm.com/tech/webservicestoolkit .