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Building a real-world Web service--part 3: putting the future in perspective. (Enterprise Solutions).

Article Excerpt
Web are the new "it" in the IT world, and vendors are rushing in to stake claims in this landscape, each with a different marketing spin on how they "do Web services." However, simply sending SOAP-based messages between machines is not really "doing Web services"; this is a limited view that obscures the bigger picture.

This series of articles demonstrates what a real-world Web service is and how to build one using features of Web services with components and knowledge of RosettaNet, an industry leader in e-business process standards. Having defined the WSDL definitions and constructed an abstract process in BPEL4WS in the first two installments, I now focus on implementation. This article is all about implementation and construction ... bring your hard hat along.

Using the Engine: BPWS4J

This installment demonstrates the creation and execution of a simple version of the e-business dialogues we've been building in this series. I'll create a bunch of BPEL, WSDL, and Java files using the BPEL4WS Editor, and Eclipse, and then execute them on the runtime engine, BPWS4J. I'll also show you how to install all the tools and components necessary to create and run e-business dialogues for yourself. The complete source code for this article is available at www.sys-con.com/xml/sourcec.cfm.

Setting up the Environment

Before I talk about the business dialogue we're constructing in this article, I want to dive right into setting up the environment. I encourage you to take a hands-on approach and experiment with the environment as you work through the article. The purpose is to set up an environment to develop and execute asynchronous business processes to perform the e-business dialogue we've been developing. Here is a list of requirements for this task:

* Java SDK from Sun Microsystems: http://java.sun.com/ j2se. I used J2SE 1.4.1.

* Eclipse, an open-source IDE from Eclipse.org: www.eclipse. org/downloads/index.php. I used version 2.0.2.

* Apache Tomcat 4.1, an open-source server solution for servlets and JSPs: http://jakarta.apache.org/tomcat/index.html

* BPEL4WS Engine and Editor from IBM alphaWorks: www.alphaworks.ibm.com/aw.nsf/download/bpws4j

* JavaBeans Activation activation.jar: http://java.sun.com/ products/javabeans/glasgow/jaf.html

* JavaMail mail.jar: http://java.sun.com/products/javamail

To run Eclipse, Tomcat, or the BPWS4J engine, we need the lava runtime. We'll use Eclipse to write, compile, and execute any lava classes that we build along the way. To create a process, we'll use the BPEL editor, which is available as an Eclipse plug-in. To run a business process we need the BPWS4J engine, which runs on Tomcat. Finally, the activation and mail APIs are used for communication between the engine and clients.

Installing the Components

The first step is to install the Java SDK; just click on the installer file you downloaded and follow instructions. Test the installation by typing java--version in a command/shell window. You should see:

java version "1.4.1" Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1-b21) Java HotSpot(TM) Client VM (build 1.4.1-b21, mixed mode)

The next step is to install the Java Activation Framework. I simply removed activation.jar from the jaf-1_0_2.zip file I'd downloaded and placed it in the jre/lib/ext directory. To install JavaMail, I opened up the javamail-1_3.zip file imap.jar, mail.jar, smtp.jar, pop3.jar, and mailapi.jar into/jre/lib/ext. These files are automatically picked up by the lava runtime.

Next we install Apache Tomcat. The installation is straightforward; just follow the steps in the installation wizard. To test the installation, start up Tomcat and type http://localhost:8080/in your Web browser. If the installation is working, you should see the Apache administration page.

Next we install...

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