Troubleshooting mule

1. Troubleshooting Mule

2. • With so many integration points and applications of Mule,
troubleshooting issues can be a daunting task for those just starting
out with Mule. This post will provide a few tips on how to get to the
root of issues you may encounter.

3. Set up your IDE for debugging
• One of the “biggest bang for the buck” things you can do is to take a
few minutes to set up your favorite IDE for Mule debugging. My IDE
of choice is Eclipse, but there are also directions on setting up IntelliJ
here. I would highly recommend installing the MuleIDE eclipse
plugin. It allows you to quickly create new Mule projects and to run
Mule configurations against an installation with a few clicks of the
mouse.

4. Log4J settings
• In addition to attaching a debugger for troubleshooting, you can
bump up the logging level in order to dig deeper into what’s going on
inside of Mule. If you are running Mule standalone, there is a log4j
configuration file located at MULE_HOME/conf/log4j.properties. If
you have narrowed down your issue to a certain package, you can
enable debug logging just for that package so you are not
overwhelmed by a barrage of non-related logging messages. For
instance, if you just want to get more logging for the http transport,
you can add the following line to your log4j.properties file:
• log4j.logger.org.mule.transport.http=DEBUG

5. Check your environment
• If you are like me, you have several JVMs installed on your system and
they can easily get mixed up when executing Mule on the command
line, from an IDE, from an application server, etc. It is especially
important to know which jvm you are using when you are building
Mule code as the jvm needs to have JAXP implementation jars under
the jre/lib/endorsed directory.
• I run on Linux and for working on the command line I set up an
environment file which gets automatically sourced when I log in. I put
this at the end of my ~/.bashrc file:

6. • export M2_HOME=~/apache-maven-2.0.9
• export ANT_HOME=~/apache-ant-1.7.1
• export JAVA_HOME=/usr/lib/jvm/java-1.5.0-sun-1.5.0.16
• #export JAVA_HOME=/usr/lib/jvm/java-6-sun-1.6.0.10
• export
PATH=$JAVA_HOME/bin:$M2_HOME/bin:$ANT_HOME/bin:$PATH

7. • In an IDE such as Eclipse, you can add additional JREs under Window -
> Preferences -> Java -> Installed JREs.
• In an application server, there are usually shell files which you can
edit to add the appropriate environment settings to. For example, in
Tomcat you can specify your jvm and jvm options in the
TOMCAT_HOME/conf/catalina.sh file.

8. Peel back the layers; take a step back
• It’s very easy to lose site of the forest for the trees when running
Mule. For example, take a configuration file which you embed in a
war file and deploy it to an application server. When the app server
starts up, it may simply log that it cannot deploy the war. In some
cases you can start your troubleshooting by trying to run your
configuration file in a standalone Mule installation so you can rule out
your application server configuration as the culprit. When that’s not
an option such as when your mule configuration is tightly integrated
with app server resources or the war file, try changing the logging
levels and make sure that the necessary ports are open. The key is to
try and simplify your environment so you can quickly get to the root
of the issue.

9. Check Jira for known issues
• Sometimes an issue you are encountering has already been reported
by someone else. Make use of the Jira search function to see if you
can find your issue and if it’s already been fixed in a later version. Jira
can be accessed here. The ‘Quick Search’ tool at the top right of the
page works very well to search for exception messages or keywords.

10. When all else fails, don’t be afraid to ask for
help!
• If you find yourself struggling with an issue, remember that this is a
community project. There are lots of experienced people reading the
mailing lists ready to help out. This includes both community
members and MuleSource engineers who constantly monitor and
respond to posts on the mailing lists. Here are a few tips before you
post