[slf4j-user] Per-web-app logging with jars on the server's classpath

[Mark Stralka]

Jacob Kjome <hoju <at> visi.com> writes:

> 
> 
> Your repository selector is based on classloader, right?  Doesn't 
> JBoss use a "Unified Classloader" strategy?  That is, every app 
> running on the server uses the same classloader?  That is, unless it 
> is configured otherwise.  If this is truly the case, then you 
> repository selector will not separate logger repositories under 
> JBoss.  And I strongly recommend you avoid Classloader-based 
> repository selectors.  You'd be better off using a JNDI-based 
> repository selector.  If you use Log4j 1.3, one is already available 
> [1].  If not, you can grab the one from the sandbox [2].  Note that a 
> Classloader-based version exists there, but you should ignore that 
> and look at the ContextJNDISelector.  Can you try this out and see if 
> it works for you?
> 
> [1] 
>
http://logging.apache.org/log4j/docs/api-1.3/org/apache/log4j/selector/ContextJNDISelector.html
> [2] 
>
http://svn.apache.org/viewvc/logging/sandbox/log4j/log4j_sandbox/tags/LOG4J_SANDBOX_ALPHA3/src/java/org/apache/log4j/selector/
> 
> Jake
> 

Hi Jake, 
I upgraded to 1.3alpha8 and implemented the ContextJNDISelector as you suggested
but I'm still having problems.  To clarify, we're using Weblogic 8.1 SP4, not
JBoss - I only named the file JbossAppRepositorySelector because that was the
name of the file I got from their wiki.  

I think the challenge with the way we're implementing logging is that most of
our JAR files are loaded on Weblogic's classpath, and we need each web app to be
able to write log entries for classes in those JARs to its own log file.

The LogManager.repositorySelector is a static variable, which I think is only
loaded once by Weblogic since it's on the server's classpath

Weblogic classpath:
myframework.jar (our custom code)
--Includes:
----com.myframework.web.StartupListener (extends Spring's ContextLoaderListener) 
----com.myframework.web.UserFormController (and other various classes)
----com.myframework.service.XyzManager (business layer)
----com.myframework.dao.XyzDao (data layer)
spring.jar
log4j.jar (now v1.3alpha8)
slf4j*.jar
jcl104-over-slf4j-1.3.0.jar
other JARs

Each Web App (appA, appB, etc - we have dozens of WAR files):
Uses Spring to configure the classes from myframework.jar (which is NOT in
WEB-INF/lib)
Uses com.myframework.web.UserFormController and needs to write log entries to
its own file (appA.log, appB.log, etc)
Each WAR has its own "log4j_webapp.properties" in WEB-INF/classes

web.xml:
<listener>
  <listener-class>
     com.myframework.web.StartupListener
  </listener-class>
</listener>
...
<env-entry>
	<description>Logging Setup</description>
	<env-entry-name>log4j/context-name</env-entry-name>
	<env-entry-value>appA (or appB, appC, etc)</env-entry-value>
	<env-entry-type>java.lang.String</env-entry-type>
</env-entry>
<env-entry>
	<description>Logging Setup</description>
	<env-entry-name>log4j/configuration-resource</env-entry-name>
	<env-entry-value>log4j_webapp.properties</env-entry-value>
	<env-entry-type>java.lang.String</env-entry-type>
</env-entry>

When I start Weblogic with several WARs deployed, all the log entries for the
common classes from myframework.jar (which is most of them) only get written to
the log file for the WAR that was loaded first alphabetically (appA.log
usually).  appB.log, appC.log, etc get created but they're always empty.

I guess an alternative to separate log files would be to somehow inject the
webapp's name into any logging message that is written to one common log file -
I'm not sure how to do that given that most of the classes are in
myframework.jar and would have to somehow lookup the webapp that is currently
using it.
Thanks again for any suggestions or insight