Java and XML

The Real World

We conclude this chapter with a short look at some important details of using XML-RPC in the real world. This continues the focus on allowing you to use XML not because it is the newest and neatest technology, but because it is the best for solving certain situations. All of the knowledge within this book, all the XML specifications, and other XML books will not make your application operate as well as it could, if you do not know when and how to use XML and XML-RPC correctly! This section, then, highlights some of the common issues that arise in using XML-RPC.

Where’s the XML in XML-RPC?

After working through this chapter, you may have been surprised that we didn’t write any SAX, DOM, or JDOM code. In fact, we used very little XML directly at all. This is because the XML-RPC libraries were responsible for the encoding and decoding of the requests that our client sent to and from the server. While this may seem a little bit of a letdown, as you didn’t write any code that directly manipulates XML, you are definitely using XML technology. The simple request to the sayHello( ) method was actually translated to an HTTP call that looks like Example 10.10.

Example 10-10. XML-RPC Request After Encoding

POST /RPC2 HTTP/1.1 User-Agent: Tomcat Web Server/3.1 Beta (Sun Solaris 2.6) Host: newInstance.com Content-Type: text/xml Content-length: 234 <?xml version="1.0"?> <methodCall> <methodName>hello.sayHello</methodName> <params> <param> <value><string>Brett</string></value> </param> ...