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Wrap a Stateless Session EJB as a Web Service with Apache Axis
by Alexander Prohorenko and Olexiy Prohorenko
Though Web Services is now more than just a buzzword, not too many developers are utilizing them in enterprise applications. This article will help to get some hands-on experience by showing you how to wrap a session stateless EJB as a Web service and deploy it with Apache Axis. You will be able deploy this EJB on virtually any application server, with only few minor changes to the deployment descriptors.
What You Will Need
You'll be using the following software:
All code in this article was compiled and run on Windows XP, but tt should work on any operating system with only minor changes to the path names.
The Benefits of Web Services
Suppose you have an enterprise application with numerous EJB's—an e-commerce site, with different products and prices. You want some of your customers to interact with your business logic, with the help of your EJBs. But having all your business logic in EJB limits you to Java-based clients.
This is where Web services can help. Of course, EJB is not a Web Service, but with the help of Apache Axis, you can wrap it into a Web service. Axis comes with a general Web service provider implementation that can wrap any stateless enterprise-session EJB that is individually deployed within the J2EE container. This means your client can be almost any application and you don't need to do a single code line change to your business component.
You may be wondering why you need to have an EJB at all, if a Web service can consist of a simple Java class? Firstly, using EJB lends flexibility and scalability to your enterprise application—and not just for a Web service. Secondly, why bother re-writing code or adding additional classes if you can simply wrap existing components? EJB components beginning were created for distributed computing and are perfectly suited for exposure as Web Services. Features like declarative transactions and security can also be leveraged if you decide to use EJB components as Web services. J2EE 1.4 allows exposing only stateless session beans, but isn't that exactly the EJB you're using for
your session facade pattern?
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