A Web Service is the provision of one or more methods that can be invoked by some external site. The external site contacts the webserver of the site providing the Web Service to get a method of the Web Service executed. It is usually a program running on the external site that wants the result of a call of the method. A website might be providing Web Services in several different areas.

Although some people assume that Web Services requires you to use Microsoft's .NET Framework, there are many rival products. In this document, we will look at Axis, a Web Services product from Apache. This product is targetted at Java programmers.

The main aim of this document is to demonstrate how easy it is for any Java programmer:

• to provide Web Services;
• to run Java programs that access Web Services provided on computers around the world.

Besides demonstrating this, the document will also look at some other topics:

• In order to provide Axis Web Services, it is necessary to have a webserver program capable of running servlets. So we will look at the installation and use of a program called tomcat.
• In order to communicate with a Web Service, it is necessary to use two XML languages: WSDL and SOAP. We will briefly look at these languages.
• As has already been mentioned, Microsoft's .NET Framework can be used for Web Services. We will look at whether it is easy to interoperate Axis and .NET for Web Services.

Although the instructions given in this document assume you are using Windows, Linux could be used instead. The document also assumes that the Java 2 SDK has been installed.