When WebSphere Application Server is run, it records information about its activities in its message log. The message log on each host captures events that show a history of the activities on that host. Some of the entries in the log are informational and others report system exceptions, such as returned CORBA exceptions.
If you encounter run-time errors, it is often useful to read the message log and try to diagnose the problem yourself. If you still need assistance from IBM to help you diagnose problems, you can provide the message log to your IBM service personnel.
There is one message log for each host machine. The file is called activity.txt by default, and it resides in the WebSphere Application Server service subdirectory. You can set the com.ibm.CORBA.logger.directoryName run-time property to specify an alternate location. You can also specify the maximum size of the message log with the com.ibm.CORBA.logger.maxLogFileSize run-time property. The message log file is automatically created when the first log entry needs to be written.
Because the message log is an accumulation of information, it always contains extraneous data. Some message log entries report serious failures, but many of them only report on the execution of activities, expected exceptions, or warnings of potentially dangerous situations. For example, in most instances, lower level components write an entry in the message log when they decide to throw an exception, even when the caller of the lower level component is prepared to handle the exception and continue processing on a normal code path. Although all of these entries on activities, handled exceptions, and warnings can make it difficult to read the log, sometimes they provide useful data to help you determine the exact cause of the problem that you are diagnosing.
If you need to do low-level debugging of problems identified in the message log, you can turn on tracing for appropriate components and then study the detailed information generated. For more information about setting trace-related run-time properties, see "Specifying properties for CORBA C++ clients and servers" and "Run-time properties for CORBA clients and servers".
Note: tracing must be used only in situations where you need to diagnose a problem or otherwise capture very detailed information about the operation of the ORB and the application. The use of the trace capabilities result in performance degradation, so they should not be used during normal operation.
If you turn on tracing for a component type, extra detailed information is recorded in one or more trace logs for the host. Multiple trace files can be generated if needed. The trace log files are stored in the WebSphere Application Server's service subdirectory by default. Set the com.ibm.CORBA.logger.directoryName run-time property to specify an alternate location. Trace log files are automatically created and given unique names that are determined by using the process id, thread id, and current time stamp.