multiple SLF4J bindings Error with activemq-all-5.6.0.jar

Question

When I upgrade to activemq-all-5.6.0

I get this error during server startup

SLF4J: Class path contains multiple SLF4J bindings

I don't have this issue when using activemq-all-5.5.1

On checking I do find that there StaticLoggerBinder.class in both activemq-all-5.6.0.jar and slf4j-log4j12-1.5.10.jar which is causing the issue

Please do help in debugging this issue

My pom.xml is as follows

<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-api</artifactId>
    <version>1.5.10</version>
</dependency>
<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>jcl-over-slf4j</artifactId>
    <version>1.5.10</version>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-log4j12</artifactId>
    <version>1.5.10</version>
    <scope>runtime</scope>
</dependency>

The active mq dependency is like this

Old Version 5.5.1 (This works)

<dependency>
    <groupId>org.apache.activemq</groupId>
    <artifactId>activemq-all</artifactId>
    <version>5.5.1</version>
</dependency>

New Version 5.6.0 (This gives the error)

<dependency>
    <groupId>org.apache.activemq</groupId>
    <artifactId>activemq-all</artifactId>
    <version>5.6.0</version>
</dependency>

Thanks in advance.

Answer 1

The ActiveMQ guys use the Maven Shade Plugin to create the activemq-all "ueber" jar. Somewhere between version 5.5.1 and 5.6.0 they added the org.slf4j:slf4j-log4j12 dependency - hence your problem.

Unfortunately because they used the shade plugin you can not use exclusions in your activemq-all dependency definition in your POM.

Instead you will need to completely replace the activemq-all dependency with all the required individual dependencies (except of course the org.sl4j-log4j12 one).

The following page details all the required dependencies: http://activemq.apache.org/initial-configuration.html#InitialConfiguration-RequiredJARs

Alternatively the following is the list of all dependencies (required and optional) included in the activemq-all jar (taken from the configuration of the shade plugin in the activemq-all pom):

org.apache.activemq:activemq-camel
org.apache.activemq:activemq-core
org.apache.activemq:activemq-console
org.apache.activemq:activemq-jaas
org.apache.activemq:activemq-optional
org.apache.activemq:kahadb
org.apache.geronimo.specs:geronimo-jms_1.1_spec
org.apache.geronimo.specs:geronimo-jta_1.0.1B_spec
org.apache.geronimo.specs:geronimo-j2ee-management_1.1_spec
org.apache.geronimo.specs:geronimo-annotation_1.0_spec
org.slf4j:slf4j-api
org.slf4j:slf4j-log4j12
log4j:log4j

Hope that helps.