Logging is one of the most important monitoring tools of a production server. A properly configured logging system is vital for identifying errors, security threats, and usage patterns. WSO2 ESB uses a log4j based logging mechanism through the Apache Commons Logging facade library. The log4j.properties file, which governs how logging is performed by the server, is in the ESB_HOME/lib directory. In general, you should not modify log4j.properties directly. Instead, you set up and modify logging using the ESB management console. The settings in the management console override the settings in log4j.properties.
A logger is used to log messages for a specific system or application component. Loggers are normally named using a hierarchical, dot-separated namespace and have a “child-parent” relationship. For example, the logger named "root.sv" is a parent of the logger named "root.sv.sf" and a child of “root.”
The following topics provide more information about logging: