| 1 | --- |
| 2 | id: java-application |
| 3 | since: 2.4 |
| 4 | --- |
| 5 | |
| 6 | LTTng-UST provides a _logging_ back-end for Java applications using |
| 7 | either |
| 8 | <a href="http://docs.oracle.com/javase/7/docs/api/java/util/logging/Logger.html" class="ext"><code>java.util.logging</code></a> |
| 9 | (JUL) or |
| 10 | <a href="http://logging.apache.org/log4j/1.2/" class="ext">Apache log4j 1.2</a>. |
| 11 | This back-end is called the _LTTng-UST Java agent_, and it is responsible |
| 12 | for the communications with an LTTng session daemon. |
| 13 | |
| 14 | From the user's point of view, once the LTTng-UST Java agent has been |
| 15 | initialized, JUL and log4j loggers may be created and used as usual. |
| 16 | The agent adds its own handler to the _root logger_, so that all |
| 17 | loggers may generate LTTng events with no effort. |
| 18 | |
| 19 | Common JUL/log4j features are supported using the `lttng` tool |
| 20 | (see [Controlling tracing](#doc-controlling-tracing)): |
| 21 | |
| 22 | * listing all logger names |
| 23 | * enabling/disabling events per logger name |
| 24 | * JUL/log4j log levels |