Basic mode and HPEL mode

Two modes of logging and tracing exist in the product, which are basic mode and High Performance Extensible Logging (HPEL) mode. Use this topic to understand the differences between these modes.

Note: This topic references one or more of the application server log files. As a recommended alternative, you can configure the server to use the High Performance Extensible Logging (HPEL) log and trace infrastructure instead of using SystemOut.log , SystemErr.log, trace.log, and activity.log files on distributed and IBM® i systems. You can also use HPEL in conjunction with your native z/OS® logging facilities. If you are using HPEL, you can access all of your log and trace information using the LogViewer command-line tool from your server profile bin directory. See the information about using HPEL to troubleshoot applications for more information on using HPEL.

Basic mode, the default mode, is the existing log and trace framework from prior releases of WebSphere® Application Server. Any existing scripts and tools you have that use logs and trace might need minor modifications to work with HPEL mode.

To take advantage of the new log and trace framework, HPEL mode must be enabled. Once HPEL mode is enabled the JVM logs (typically SystemOut.log and SystemErr.log), the trace log (typically trace.log), and the service log (typically activity.log) are no longer written to. Instead, log and trace content is written to a log data or trace data repository in a proprietary binary format and, if configured, to a text log file. Disabling the writing of the text log file results in the largest possible performance benefit of HPEL. A log viewing tool, LogViewer, is provided to allow for viewing, filtering, monitoring, and formatting the log and trace data in the repositories.

The following figure shows the files used by the basic mode and HPEL mode log and trace facilities. When enabled, the HPEL text log file stores content from Java™ trace (optional), Java logs, System.out, and System.err. You can disable the HPEL text log in cases where it is not needed as indicated by the dotted lines.

Basic mode and HPEL mode event storage. — Figure 1. Log and trace files

Table 1. Basic mode and HPEL mode files . This table shows where each of the application and application server log, trace, JVM log, and native JVM log content is routed and how to view that content.
Source	Basic mode files	HPEL mode files	How to view the HPEL files
System.out	SystemOut.log trace.log (when trace enabled)	logdata/*.wbl TextLog_<timestamp>.log (when text log enabled)	logdata - use LogViewer, with optional filtering, to render log data repository as readable text, then use any text editor TextLog - any text editor
System.err	SystemErr.log	Same as System.out	Same as System.out
java.util.logging (levels DETAIL and higher)	SystemOut.log activity.log trace.log (when trace enabled)	Same as System.out	Same as System.out
java.util.logging (levels beneath DETAIL)	trace.log	tracedata/*.wbl TextLog_<timestamp>.log (when text log enabled)	tracedata - use LogViewer, with optional filtering, to render trace data repository as readable text, then use any text editor TextLog - any text editor
native cout	native_stdout.log	native_stdout.log	Any text editor
native cerr	native_stderr.log	native_stderr.log	Any text editor

The following table describes the MBean services:

Table 2. Basic mode and HPEL mode MBeans . This table shows the JMX MBeans that are associated with the basic mode and HPEL mode log and trace frameworks.
Basic mode MBeans	HPEL mode MBeans	HPEL MBean Descriptions
RasLoggingServiceMBean	RasLoggingServiceMBean	Provides JMX Notification
	HPELLogDataServiceMBean	Configures the log repository such as location, retention policy, out of space behavior, buffering, and file switching
	HPELTraceDataServiceMBean	Configures the trace repository such as location, retention policy, out of space behavior, buffering, and file switching
	HPELTextLogServiceMBean	Configures the text log such as location, retention policy, out of space behavior, buffering, file switching, and SystemErr or SystemOut format
TraceServiceMBean	HPELControlServiceMBean	Configures trace specification levels, and provides access to log and trace repository content