Why my TomEE/Tomcat doesn’t start because of listener?

Sometimes Tomcat (or TomEE) doesn’t start saying something like:

SEVERE: Skipped installing application listeners due to previous error(s)
Nov 26, 2012 9:22:46 AM org.apache.catalina.core.StandardContext startInternal
SEVERE: Error listenerStart
Nov 26, 2012 9:22:46 AM org.apache.catalina.core.StandardContext startInternal
SEVERE: Context [/demo] startup failed due to previous errors

So great our code doesn’t work…but we don’t know why. Since that’s often while the class is instantiated that’s hard to debug your own code.

LogSql flag in OpenEJB and TomEE

Getting SQL queries is particularly important to identify potential bottlenecks and understand what is doing an application.

We often use external tools like jamon, slf4j-jdbc and so on to get this information.

There are two main drawbacks:

• it often breaks a bit the configuration since you replace your driver by the library one and your jdbc url by another one (or at least your original one with some additional information)
• You need another library (find it, learn it etc…)

That’s why in OpenEJB and TomEE we added a property LogSql which simply logs all queries, no need of hard configuration, that’s just a boolean.

OpenEJB, TomEE and log framework

OpenEJB and TomEE allows you to switch logging framework pretty easily if you prefer log4j, slf4J or any other library for that purpose.