3. 3 Setting up a development environment
Before we can build our first tag, we need to configure our development environ-ment.
This development environment should at least make it possible to:
- Compile the tags with the servlet, JSP, and JSP custom tags API 1
- Test the developed tags
- Browse the JSP custom tags API documentation.
1 We will take a look at the JSP custom tag API in chapter 4.
There are several Java IDEs in today's market, some of which provide fine support
for servlet and JSP development; however, we are not going to work with any par-ticular IDE
because it is highly unlikely that you would have the same one that we
select. Also, IDEs are notorious for lagging behind the leading edge of the Servlet
and JSP API. Instead we explain how to fetch all the ingredients for a minimal devel-opment
environment and how to set them up so that you may start developing tags
immediately. This development environment will be concentrated around Tomcat, 2
the reference implementation of the servlet API, and the JDK1.2.2 or above (as
available to most operating systems).
3.3.1 Installing the JDK
The first step in setting up the development environment is to install JDK1.2.2 (or
higher) on your development system. More than two years since its first appearance, JDK1.
2 can be found in a matured state on most operating systems, and this book
uses many of its new classes and interfaces, such as java.util.Iterator.
Although
JDK1.2 is recommended for tag development, a JDK1.1. x version should suffice.
Installing the JDK is an operating system-dependent task and will not be covered
here, so we'll assume that you have a JDK installed and that you point into the
installation directory with an environment variable named JAVA_HOME.
3.3.2 Installing Tomcat
Tomcat is the reference implementation of the Servlet and JSP API. It is easy to use
and install, has a very small footprint (both on the hard drive and in memory), and
is Open Source— all of which makes it a perfect learning tool. Installing Tomcat with
the basic functionality of a stand-alone servlet and JSP container is really a cinch:
- Extract the Tomcat binary distribution archive 3 (available as either .zip or
tar.gz archives).
- Define an environment variable named
TOMCAT_HOME to point to Tomcat's
installation root directory.
- Make sure that the environment variable
JAVA_HOME is defined and points
to the directory wherein you installed your JDK.
2 Tomcat's home on the web is at http://www/jakarta.apache.org
3 You can download the binary distribution directly from Tomcat's web site. The installation directives supplied
in this book apply to Tomcat versions 3.1 and 3.2.
3.3.3 Testing your Tomcat installation
To test-drive Tomcat, change the directory to TOMCAT_HOME and execute the
startup script in Tomcat's bin directory. Tomcat should start running in the back-ground
and you can test it by issuing an HTTP request (i.e., http://your.machine.name:8080/).
Once Tomcat is running, the installation of the development
environment is complete and you may start immediately to develop tags;
but first, let's look at the Tomcat distribution.
servlet. jar
The .jar file is where you find the interfaces and classes constituting the Servlet and JSP API.
This file is named servlet. jar and is located in Tomcat's Lib directory. When
compiling a servlet or JSP custom tag, you should make sure that this file is in your
compilation CLASSPATH definition.
webapps directory
Where to place your web applications for Tomcat is the next consideration. Tomcat
can generally be configured to take applications from any place you choose, but
why bother configuring individual applications when you can simply drop your
application into a single directory for deployment? The one directory approach will
prove much simpler for your first applications. Under TOMCAT_HOME there is a
subdirectory named webapps; and whenever Tomcat starts to run, it inspects this
subdirectory, searches for web-application archive files (.war), and automatically
deploys them. Moreover, if Tomcat finds subdirectories under webapps, it will
assume that these directories contain web applications. Deployment to this direc-tory
is thus a simple task.
Javadoc documentation
One last thing to consider with Tomcat is the location of the Javadoc documents for
the Servlet and JSP API. These documents are located in an application bundled
with the Tomcat samples. In the webapps directory, there's a directory named
ROOT, the home of Tomcat default root application. The root application has a
subdirectory path named docs/api where you can find the Javadoc documents for
the Servlet and JSP API (start with the file index.html). 4
With the environment configured and a basic understanding of the deployment
picture, it's time to build our first custom tag.
4 You can also browse these documents by starting Tomcat and referring to http://your.ma-chine.name: 8080/docs/api/index.html.
Stop by in one week for the next installment!
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