Roll Your Own Appenders
Though it is beyond the scope of this article, Log4j allows you to write your own custom appenders. To do this, you need to derive from the org.apache.log4j.AppenderSkeleton class. This is precisely what Jamie Tsao did to create his JMSQueueAppender class, which we used on page 5 of this article.
So Popular, It Has Imitations
Version 1.3 of Log4j marked the 22nd major public release of Log4j. Log4j is continually and rigorously enhanced to optimize performance.
And it has gained a significant following among programmers. Before the advent of Java 1.4's innate logging facility (see the sidebar, "Log4j vs. the Java 1.4 Innate Language Logging Facility,"), Log4j was one of the most common logging facilities used by the Java programming community. Log4j has even been ported to the C, C++, C#, Perl, PHP, Python, Ruby, and Eiffel languages. And also be sure to read about the Performance Impact" of logging.
Check out some of these other articles on the Log4j site.