Jakarta jmeter is an awesome tool. I deeply encourage to experiment with it. If you want to see more details on how it is implemented or write your extension it may be worth compiling it from sources on your machine.

Here is a quick guide how to setup a eclipse project and what to do to build jmeter from sources and run it locally.

Steps to compile

• Download eclipse and latest java jdk 6, edit eclipse properties to select jdk as default jre
• Download jmeter sources
• Unpack jmeter sources into your workspace folder
• Create "New Java Project" not project from ant file or anything
• Paste name of the folder you unpacked the sources to
• Once project is created you add an ant view Window > Show View > Ant
• Add build file and point to jmeter's build.xml
• Now for the tricky bit, you have to run target named download_jars as this is how jmeter will download its dependencies
• Now you are ready to run any of the targets, especially install

Enabling jMeterPlugins

Now get the set of latest jmeter plugins from google code. Unpack the bundle and drop the JMeterPlugins.jar into /lib/ext folder of your sources of jmeter.

This way you can recompile jmeter with jmeterplugins jar already in place.

Increase log level

To make it easier to debug issues and see what does happen in your suite execution edit bin/jmeter.properties and make sure you have something like:

log_level.jmeter=DEBUG
log_level.jmeter.junit=DEBUG
log_level.jmeter.control=DEBUG
log_level.jmeter.testbeans=DEBUG
log_level.jmeter.engine=DEBUG
log_level.jmeter.threads=DEBUG
log_level.jmeter.gui=WARN
log_level.jmeter.testelement=DEBUG
log_level.jmeter.util=WARN
log_level.jmeter.util.classfinder=WARN
log_level.jmeter.test=DEBUG
log_level.jmeter.protocol.http=DEBUG
# For CookieManager, AuthManager etc:
log_level.jmeter.protocol.http.control=DEBUG
log_level.jmeter.protocol.ftp=WARN
log_level.jmeter.protocol.jdbc=DEBUG
log_level.jmeter.protocol.java=WARN
log_level.jmeter.testelements.property=DEBUG
log_level.jorphan=DEBUG

log_file=jmeter.log

Now you are ready to modify jmeter code and play around.