ActiveMQ 5.5 and SLF4J 1.6

Working on a simple Hello World example for ActiveMQ, I bumped in a conflict between this Apache Message-Oriented-Middleware (MOM) and the SLF4J logging system. It is nothing serious, but I guess it is worth to enter in some detail on this issue.

SLF4J is the used as logger by ActiveMQ. Unfortunately, still in version 5.5, the SLF4J bundled version is 1.5, that's a pity, because starting from SLF4J version 1.6 if you place no binder in your application classpath, the NOP logger is assumed. The effect is that all your log goes to a logical respective of /dev/null, as to say, it disappears in thin air. That's no fun, but better than the behavior of 1.5: crashing miserably with an error like this:

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for
 further details.
Exception in thread "main" java.lang.NoClassDefFoundError: 
    org/slf4j/impl/StaticLoggerBinder
        at org.slf4j.LoggerFactory.getSingleton(LoggerFactory.java:230)
...

So, you really have to plug in a binder. I already had at hand a 1.6 plugin, I tried to used it, but I got another error:

SLF4J: The requested version 1.6 by your slf4j binding is not compatible
 with [1.5.5, 1.5.6, 1.5.7, 1.5.8, 1.5.9, 1.5.10, 1.5.11]

No compatibily.

There are a couple of solution to this issue. Or you use a plugin for that specific version, or you put the SLF4J API jar of your choice in your classpath before the ActiveMQ full jar.

I opted for the second choice, and my classpath is now referring to these jar - in this order:

• slf4j-api-1.6.4.jar
• activemq-all-5.5.1.jar
• slf4j-simple-1.6.4.jar

Actually, the SLF4J plugin could be in any place, but it is crucial that the API SLF4J jar is before the ActiveMQ one.