classloaders, commons-logging, jmx, jboss and threads

[stevecoh1]

I am porting a web application from JRun to JBoss.
This application used commons-logging on top of log4j to do its logging. Part of this application included a thread that took in a data feed, used by another part of the application.

The port was made without too much difficulty but I wanted to use JBoss's JMX facilities to control the feed, which had previously been done by a kludgey HTTP interface. So I wrote a couple of MBeans to do that. There was a question of logging within the MBeans, I wasn't sure how to get the MBeans to see commons-logging so I let the logging be done by log4j in the MBeans. That was an acceptable compromise until I wrote the bean to control starting and stopping the feed from JMX console. I used an AttributeChangeNotification mechanism with my web-app being a listener for the notification. The stop button worked like a charm. But the start button caused a new, and unforeseen problem.

When the feed thread was started from within the web app there was no problem and stopping that thread posed none either. However restarting the feed thread from the JMX console meant that the feed thread was now originating from JMX, and errors were thrown indicating that no classloader for commons-logging could be found there?

So my question is how can commons-logging be put into the JBoss server's classpath - or alternatively, is there a better way of implementing JMX for this function that doesn't have these problems.

[stevecoh1]

I tell ya, in two weeks of messing with JBoss I've learned more java than I have in the last two years. I managed to solve the problem above by saving at startup time the ClassLoader with which the application was invoked
and setting it into any new feed Thread created by the application whenever one is created. Solves the problem very nicely. Prior to this I never knew the methods
Thread.getContextClassLoader() and
Thread.setContextClassLoader() existed or what they were for.

Does anyone see any problems with this approach?

[adrian.brock]

Sounds a bit complicated.
I hope you documented what you are doing
in the source:-)

Regards,
Adrian

[stevecoh1]

I think it's much less complicated than it sounds :-)
Nonetheless, I'm open to any suggestions of simpler methods.