Logging System for Developing in Windchill 8.0

By Dmitry Tkach, isLaNd Inc.

In software development, logging is the process of inserting statements into the program that provide some kind of output information that is useful to the developer. Examples of logging are trace statements, dumping of structures and the familiar System.out.println or printf debug statements.

Log4j is a popular logging package written in Java. One of its distinctive features is the notion of inheritance. Using a logger hierarchy, it is possible to control which log statements are output at what granularity. This helps reduce the volume of logged output and minimize the cost of logging.

One of the advantages of the log4j API is its manageability. Once the log statements are inserted into the code, you can control them with configuration files. They can be selectively enabled or disabled, and sent to multiple output targets in different formats. The log4j package is designed so that log statements can remain in shipped code without reducing performance.

In the following example, we use log4j in Windchill to eliminate the headache of maintaining thousands of System.out.println statements. But first we need to do some customization. 

Setup

To use the tools we are about to install, you must set up the operating environment so that the tools know where to find what they need and the operating system knows where to find the tools.

1. Download the log4j distribution from http://jakarta.apache.org/log4j/docs/download.html. (During installation, Windchill 8.0 loj4j.jar is already there.)

2. Extract the archived files to some suitable directory. 

The Logger

The Logger is the core component of the logging process. In log4j, there are five normal levels of logger available (not including custom levels). The following descriptions are borrowed from the log4j API (http://jakarta.apache.org/log4j/docs/api/index.html).

·       Static Level DEBUG. Designates fine-grained informational events that are most useful to debug an application.

·       Static Level INFO. Designates informational messages that highlight the progress of the application at coarse-grained level.

·       Static Level WARN. Designates potentially harmful situations.

·       Static Level ERROR. Designates error events that might still allow the application to continue running.

·       Static Level FATAL. Designates very severe error events that will presumably lead the application to abort. 

In addition, there are two special levels of logging available. (Descriptions borrowed from the log4j API http://jakarta.apache.org/log4j/docs/api/index.html.)

·       Static Level ALL. Has the lowest possible rank and is intended to turn on all logging.

·       Static Level OFF. Has the highest possible rank and is intended to turn off logging.

You can use any of seven levels: Level.DEBUG, Level.INFO, Level.WARN, Level.ERROR, Level.FATAL, Level.ALL and Level.OFF.

For our example here, we created the package in src/ext folder and called – logging.

src/ext/logging/LoggingService.java

src/ext/logging/LoggingServiceFwd.java

src/ext/logging/LogginServiceHelper.java

src/ext/loggin/StandardLoggingService.java

src/ext/logging/LoggingUtils.java 

To check the loading process using log files, we need to configure Log4j for Windchill Server. Log4j is initialized via a property file. Two configuration files exists. The primary one is <i>PDM.lsf</i> in the codebase directory of the Windchill server. For development purposes, a developer may create a <i>PDMdev.lcf</i> exists. <i>PDM.lsf</i> will not be used.

The Appender

The Appender controls how the logging is output. The available appenders are as follows. (Descriptions borrowed from the log4j API http://jakarta.apache.org/log4j/docs/api/index.html.)

·       ConsoleAppender: Appends log events to System.out or System.err using a layout specified by the user. The default target is System.out.

·       FileAppender. Appends log events to a file.

·       DailyRollingFileAppender. Extends FileAppender so that the underlying file is rolled over at a user chosen frequency.

·       RollingFileAppender. Extends FileAppender to back up the log files when they reach a certain size.

·       WriterAppender. Appends log events to a Writer or an OutputStream depending on the user's choice.

·       SMTPAppender. Sends an email when a specific logging event occurs, typically on errors or fatal errors.

·       SocketAppender. Sends LoggingEvent objects to a remote a log server, usually a SocketNode.

·       SocketHubAppender. Sends LoggingEvent objects to a set of remote log servers, usually  SocketNodes.

·       SyslogAppender Sends messages to a remote syslog daemon.

·       TelnetAppender. Specializes in writing to a read-only socket.

You can also implement the Appender interface to create your own ways of outputting log statements.

PDM-Wide Log4j Configuration

Here is a sample PDM.lsf configuration file that would go in the Windchill logs folder.

Appenders

Stdout is set to be a ConsoleAppender that outputs to System.out.

log4j.appender.stdout=org.apache.log4j.ConsoleAppender

log4j.appender.stdout.layout=org.apache.log4j.PatternLayout

log4j.appender.stdout.threshold=WARN

The method server adds a timestamp to every line, so don't do it via log4j too.

log4j.appender.stdout.layout.ConversionPattern=%-5p %c{1} - %m%n

Send Deere messages to $WT_HOME/logs/test.log

log4j.appender.test=org.apache.log4j.RollingFileAppender

log4j.appender.test.File=${deere.logs.dir}/test.log

log4j.appender.test.MaxFileSize=6MB

log4j.appender.test.MaxBackupIndex=0

log4j.appender.test.layout=org.apache.log4j.PatternLayout

log4j.appender.test.layout.ConversionPattern=%d{DATE} %-5p %c{1} - %m%n

Loggers

By default, everything goes to the stdout appender.

log4j.rooLogger=WARN, stdout

For third-party packages, we only want priority WARN or above. Some of these packages use Jakarta Commons Logging wrapper which, when log4j is found on the classpath, routes the logs through log4.

log4j.logger.org.apache=WARN

log4j.logger.org.apache.commons.httpclient=WARN

log4j.logger.httpclient.wire=WARN

log4j.logger.ext.cf.loaders.Test=DEBUG, deere

log4j.additivity.ext.cf.loaders.Test=false

Setup for Windchill

So now, to configure several log files at once for each module, you need to set up log4j for Windchill Server.

1. Copy the log4j.jar archive to the Windchill codebase directory.

2. Create the PDM.lcf (production servers) or PDMDev.lcf (development servers)

3. Initialize the log4j in the new sources code files if you need.

4. Restart the Tomcat and Method Server.

Dmitry Tkach is software architect at isLaNd Inc.(www.ittechstar.com). He can be reached by email at dmitrytkach1@hotmail.com.