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Chapter 20. Logging

20.1. Java EE containers
20.2. Servlet containers
20.3. Weld SE

Weld is using JBoss Logging, an abstraction layer which provides support for the internationalization and localization of log messages and exception messages. However, JBoss Logging itself does not write any log messages. Instead, it only constructs a log message and delegates to one of the supported logging frameworks.

The supported "back-end" frameworks include:

  1. jboss-logmanager
  2. Log4j
  3. SLF4J
  4. JDK logging

A system property org.jboss.logging.provider may be used to specify the logging framework directly. Supported values are jboss, jdk, log4j and slf4j. If this system property is not set, JBoss Logging will attempt to find the logging frameworks from the above-mentioned list on the classpath - the first one found is taken.

If using Weld with a Java EE container (e.g. WildFly) the logging configuration is under the direction of the container. You should follow the container-specific guides to change the configuration (e.g. WildFly - Logging Configuration).

Unlike the case of Java EE containers a web application deployed to a servlet container usually bundles a logging framework and possibly some configuration file. In this case, the configuration is in hands of the application developer (provided the bundled framework is supported by JBoss Logging).

If no logging framework is bundled follow the container-specific guides to change the configuration (e.g. Logging in Tomcat).

This is very similar to servlet containers except the class loading is usually even less complicated.


If you just want to see the debug log messages as quickly as possible in Weld SE try this:

  1. add org.slf4j:slf4j-simple on the classpath and remove other SLF4J bindings,
  2. set the "back-end" framework to slf4j,
  3. and change the level for org.jboss.weld, e.g.:

    mvn clean test -Dtest=MyWeldSETest -Dorg.jboss.logging.provider=slf4j -Dorg.slf4j.simpleLogger.log.org.jboss.weld=debug