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From "Bill Schneider" <bschnei...@vecna.com>
Subject log4j writing to ServletContext.log()
Date Fri, 17 Jan 2003 18:30:32 GMT
To get around the problems I was having with log4j in a clustered
environment (multiple processes on one filesystem), I wrote a new appender
that writes to the servlet log as if you called servletContext.log(...).
Has anyone thought of doing this before?  Hadn't seen much on the lists
about it.  I can submit the code if anyone is interested.

The catch is, somehow you have to initialize the appender with the
ServletContext objcet.  I arrived at a method "static public void
setServletContext".  Since we're already initializing log4j from a
ServletContextListener, it's fairly trivial to call
ServletLogAppender.setServletContext(...) from the context listener
immediately after initializing log4j.

[[Speaking of which, it might be nice to have a standard log4j context
loader that you can just dump into web.xml and point at a properties file.
We've implemented one trivially, but I'm sure lots of other folks already
rolled their own too.]]

Benefits: only one log file to worry about rolling and archiving; log4j
events go right alongside app server events; and the app server should take
responsibility for synchronizing writes or separating logs by process.

Problems: Assumes a one-to-one mapping between classloaders and servlet
contexts.  It won't work inside EJBs, since EJBs are in a different

The JMSAppender is the real long-term solution, although that requires
someone to be listening for and recording the messages.  But a
ServletLogAppender will work nicely in a cluster of "pure" (non-EJB-ified)

-- Bill

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