Trace and log configuration


 

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We can only enable trace for an application client or standalone process at process startup.

In WAS, V6 and later, a logging infrastructure, extending Java Logging, is used. This results in the following changes to the configuration of the logging infrastructure in WAS:

Java Logging does not distinguish between tracing and message logging. However, previous versions of WAS have made a clear distinction between those kind of messages. In WAS V6 and later, the differences between tracing and message logging are as follows:

 

Trace and logging strings

In WAS, V5.1.1 and earlier, trace strings were used for configuring tracing only. Starting in WAS, V6 and later, the "trace string" becomes a "logging string"; it is used to configure both tracing and message logging.

In WAS V5.1.1 and earlier, the trace service for all WAS components is disabled by default. To request a change to the current state of the trace service, a trace string is passed to the trace service. This trace string encodes the information detailing which level of trace to enable or disable and for which components.

In all versions of WAS, the tracing for all components is disabled by default. To change to the current state of the tracing and message logging, a logging string must be constructed and passed to the server. This logging string specifies what level of trace or logging to enable or disable for specific components.

We can type in trace strings (or logging strings), or construct them using the admin console. Trace and logging strings must conform to a specific grammar.

For WAS V5.1.1 and earlier, the spec of this grammar is as follows:

TRACESTRING=COMPONENT_TRACE_STRING[:COMPONENT_TRACE_STRING]*
COMPONENT_TRACE_STRING=COMPONENT_NAME=LEVEL=STATE[,LEVEL=STATE]*
LEVEL = all | entryExit | debug | event
STATE = enabled | disabled
COMPONENT_NAME = COMPONENT | GROUP

For WAS, V6 and later, the previous grammar is supported. However a new grammar has been added to better represent the underlying infrastructure:

LOGGINGSTRING=COMPONENT_LOGGING_STRING[:COMPONENT_LOGGING_STRING]*
COMPONENT_TRACE_STRING=COMPONENT_NAME=LEVEL
LEVEL = all | (finest | debug) | (finer | entryExit) | (fine | event ) | detail | config | info | audit | warning | (severe | error) | fatal | off
COMPONENT_NAME = COMPONENT | GROUP

The COMPONENT_NAME is the name of a component or group registered with the trace service logging infrastructure. Typically, WAS components register using a fully qualified Java class name, for example...

com.ibm.servlet.engine.ServletEngine

In addition, we can use a wildcard character of asterisk (*) to terminate a component name and indicate multiple classes or packages.

For example, use a component name of com.ibm.servlet.* to specify all components whose names begin with com.ibm.servlet. Use a wildcard character of * at the end of the component or group name to make the logging string applicable to all components or groups whose names start with specified string.

For example, a logging string specifying "com.ibm.servlet.*" as a component name will be applied to all components whose names begin with com.ibm.servlet. When an * is used by itself in place of the component name, the level the string specifies, will be applied to all components.

The following are examples of using an * in logging strings. Note that the * in the logging string does not need to have a period (.) in front of it. The period (.) can be used anywhere in the logging string.

In WAS V5.1.1 and earlier, you could set the level to "all=disabled" to disable tracing. This syntax, beginning with V6.0, will result in LEVEL=info; tracing will be disabled, but logging will be enabled.

In WAS V6 and later, "info" is the default level. If the specified component is not present (*=xxx is not found), *=info is always implied. Any component not matched by the trace string will have its level set to info.

If the logging string does not start with a component logging string specifying a level for all components, using the "*" in place of component name, one will be added, setting the default level for all components.

  • STATE = enabled | disabled is not needed in V6 and later. However, if used, it has the following effect:

    • "enabled" sets the logging for the component specified to the level specified

    • "disabled" sets the logging for the component specified to one level above the level specified.

      Logging string Resulting logging level Notes
      com.ibm.ejs.ras=debug=disabled com.ibm.ejs.ras=finer debug (version 5) = finest (version 6)
      com.ibm.ejs.ras=all=disabled com.ibm.ejs.ras=info "all=disabled" will disable tracing; logging is still enabled.
      com.ibm.ejs.ras=fatal=disabled com.ibm.ejs.ras=off  
      com.ibm.ejs.ras=off=disabled com.ibm.ejs.ras=off off is the highest severity

     

    Proceed from broad to specific trace specifications in the trace string

    Best practice: Start the trace string from the most broad component groups and then select more specific traces. The advantage to this approach is that the trace settings for classes or packages that are contained in a larger group are specified correctly by including them later in the trace string

    The logging string is processed from left to right. During the processing, part of the logging string might be modified or removed if the levels they configure are overridden by another part of the logging string. Groups that contain packages that disable traces disable any packages that are enabled previously on the same line. For example:

    *=off : MyGroup1=info : MyGroup2=finest : com.mycompany.mypackage.*=info : com.mycompany.mypackage.MyClass=finest

    This trace string indicates that the only tracing should come from the MyGroup1 group, the MyGroup2 group, and the com.mycompany.mypackage.* package with more specific tracing for MyClass class. If we reverse this string, all tracing is disabled.

     

    Examples of legal trace strings

    Version 5 syntax Version 6 syntax
    com.ibm.ejs.ras.ManagerAdmin=debug=enabled com.ibm.ejs.ras.ManagerAdmin=finest
    com.ibm.ejs.ras.ManagerAdmin=all=enabled,event=disabled com.ibm.ejs.ras.ManagerAdmin=detail
    com.ibm.ejs.ras.*=all=enabled com.ibm.ejs.ras.*=all
    com.ibm.ejs.ras.*=all=enabled:com.ibm.ws.ras=debug= enabled,entryexit=enabled com.ibm.ejs.ras.*=all:com.ibm.ws.ras=finer




     

    Related tasks

    Enable trace on client and stand-alone applications
    Enable trace at server startup
    Enable trace on a running server
    Manage the appserver trace service