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Java and XML: SOAP
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There are two forms of installation with regard to SOAP. The first is running a SOAP client, using the SOAP API to communicate with a server that can receive SOAP messages. The second is running a SOAP server, which can receive messages from a SOAP client. I cover installation of both cases in this section.

The client

To use SOAP on a client, you first need to download Apache SOAP, available online at http://xml.apache.org/dist/soap. I've downloaded version 2.2, in the binary format (in the version-2.2 subdirectory). You should then extract the contents of the archive into a directory on your machine; my installation is in the javaxml2 directory (c:\javaxml2 on my Windows machine, /javaxml2 on my Mac OS X machine). The result is /javaxml2/soap-2_2. You'll also need to download the JavaMail package, available from Sun at http://java.sun.com/products/javamail/. This is for the SMTP transfer protocol support included in Apache SOAP. Then, download the JavaBeans Activation Framework (JAF), also from Sun, available online at http://java.sun.com/products/beans/glasgow/jaf.html. I'm assuming that you still have Xerces or another XML parser available for use.

NOTE: Ensure your XML parser is JAXP-compatible and namespace-aware. Your parser, unless it's a very special case, probably meets both of these requirements. If you have problems, go back to using Xerces.

Use a recent version of Xerces; Version 1.4 or greater should suffice. There are a number of issues with SOAP and Xerces 1.3(.1), so I'd avoid that combination like the plague.

There's a lot of talk about running SOAP over other protocols, like SMTP (or even Jabber). This isn't part of the SOAP standard, but it may be added in the future. Don't be surprised if you see it discussed.

Expand both the JavaMail and JAF packages, and then add the included jar files to your classpath, as well as the soap.jar library. Each of these jar files are either in the root directory or in the lib/ directory of the relevant installation. At the end, your classpath should look something like this:


On Windows, it should look like:

c:\>echo %CLASSPATH%

Finally, add the javaxml2/soap-2_2/ directory to your classpath if you want to run the SOAP samples. I cover setup for specific examples in this chapter as I get to them.

The server

For building a SOAP-capable set of server components, you first need a servlet engine. As in earlier chapters, I'll use Apache Tomcat throughout this chapter for examples, which is available from http://jakarta.apache.org/. You'll then need to add everything needed on the client to the server's classpath. The easiest way to do that is to drop soap.jar, activation.jar, and mail.jar, as well as your parser, in your servlet engine's library directory. On Tomcat, this is simply the lib/ directory, which contains libraries that should be autoloaded. If you want to support scripting (which is not covered in this chapter, but is in the Apache SOAP samples), you'll also need to put bsf.jar, available online at http://oss.software.ibm.com/developerworks/projects/bsf, and js.jar, available from http://www.mozilla.org/rhino/, in the same directory.

NOTE: If you are using Xerces with Tomcat, you'll need to perform the same renaming trick I talked about in Chapter 10. Rename parser.jar to z_parser.jar and jaxp.jar to z_jaxp.jar, to ensure that xerces.jar and the included version of JAXP is loaded prior to any other parser or JAXP implementation.

Now restart your servlet engine, and you're ready to write SOAP server components.

The router servlet and admin client

In addition to basic operation, Apache SOAP includes a router servlet as well as an admin client; even if you don't want to use these, I recommend you install them so you can test your SOAP installation. This process is servlet-engine-specific, so I just cover the Tomcat installation here. However, installation instructions for several other servlet engines are available online at http://xml.apache.org/soap/docs/index.html.

Installation under Tomcat is a piece of cake; you simply need to take the soap.war file located in the soap-2_2/webapps directory, and drop it in your $TOMCAT_HOME/webapps directory. That's it! To test the installation, point your web browser to http://localhost:8080/soap/servlet/rpcrouter. You should get a response like that shown in Figure 12-2.

Screen shot.
Figure 12-2. The RPC router servlet.

Although this looks like an error, it does indicate that things are working correctly. You should get the same response pointing your browser to the admin client, at http://localhost:8080/soap/servlet/messagerouter.

As a final test of both the server and client, ensure you have followed all the setup instructions so far. Then execute the following Java class as shown, supplying your servlet URL for the RPC router servlet:

C:\>java org.apache.soap.server.ServiceManagerClient http://localhost:8080/soap/servlet/rpcrouter list Deployed Services:

You should get the empty list of services, as shown here. If you get any other message, consult the long list of possible errors at http://xml.apache.org/soap/docs/trouble/index.html. A fairly complete list of problems that you can run into is there. If you do get the empty list of services, then you're set up and ready to continue with the examples in the rest of this chapter.

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