Using Apache Axis version 1 to build Web Services
by Keld H. Hansen
Introduction
The other day I was discussing Web Services with one of my Java-colleagues,
and he made this comment, "Web Services, that’s nothing more than a method call
that uses XML". I must admit that this was the shortest definition of Web
Services I’d ever heard! Despite its brevity it still describes what Web
Services is all about: a client and a server exchanging data in XML--or more
correctly--SOAP-format. What can make Web Service programming difficult is if
you have to encode and decode your data in SOAP format, or do low-level
programming of the data transport. Luckily there are many Web Service tool kits
on the market--also in the Open Source area—which greatly simplifies Web Service
development. One such tool kit is Apache Axis.
Apache Axis version 1 was announced on October 7th this year (2002). If
you’re not familiar with Axis I’d recommend you read my article "Web Services with
Axis", which was based on the first beta version of Axis. In that article I
presented a few simple examples, and also introduced you to some of the very
useful utilities in Axis.
In the present article I’ll go a step further and build a more realistic
Swing application that utilizes web services through Axis. We’ll start by doing
some "business analysis" and then build the server part of the web service. To
test this service we actually don’t need a client--Axis has a nice feature for
client-less testing which I’ll show you. Finally we’ll build and test the Swing
client. All the programs can be downloaded as a
complete working application in zip format.
If you’re interested in further reading you’ll find several very good
articles in the resources section at the end of my article.
Axis Installation
Before we look at the application I’ll give you a few tips on how to install
Axis on Tomcat.
The download is found on the Apache Axis Releases page.
In the download you’ll find an Installation
Guide. Please be sure to get the latest Installation Guide, which is of much
better quality than the ones that accompanied the Axis betas and the first drop
of version 1.
The basic purpose of the installation is to make the Axis servlet run, and
the thing that can be a challenge here is where to place the jar-files that come
with Axis. Placement depends on which JDK you’re running. Read "Step 2" from the
Installation Guide carefully.
To test the installation you enter http://localhost:8080/axis which
should bring up the following page (if it doesn’t then check "Step 2" again. Did
you remember to restart Tomcat?):
First of all you should click on "Validate" to run the "Happy" program that
shows you if the installation is OK. This verification program is a brilliant
idea. If you ever run into problems with Axis then always try the Happy page as
part of your debugging. See more details in "Step 3" in the Installation Guide.
Now click on "View" to see the web services installed per default:
Now we’re ready to explore Axis.
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