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From Ceki Gülcü <c...@qos.ch>
Subject Re: Standalone instance with multiple log4j setting
Date Wed, 31 Mar 2010 22:40:26 GMT
Nice summary of the problem. Funny you should mention logback in
relation to the longstanding logging separation problem for static
logger references in shared libraries. As of v0.9.19 released last
week, logback provides an answer. See the chapter entitled "Logging
Separation" in the logback manual. The approach is a little convoluted
but should work assuming you can follow the reasoning behind it.


On 31/03/2010 6:49 PM, Jacob Kjome wrote:
> For applications deployed as EAR files, you can't expect a webapp's
> WEB-INF/lib/log4j.jar to be picked up by EJB's deployed outside that
> webapp.  In that case, you'd need to place it in some common upper level
> (not at all in WEB-INF/lib) where both the webapp and EJB can see it.
> Of course, unless you have a server that allows you to manage the
> classloading behavior of an EAR file (i.e., set parent-last on the EAR
> as a whole), not just a WAR file, then you can't depend on classloading.
> This is where logger repository selectors come in.  You can have a
> global log4j.jar file (i.e. in the server's global classpath) and still
> separate logger repositories.  You just need to use some environmental
> value as the key to the logger repositories in the selector, such as
> thread, classloader, or JNDI.  I think you might benefit from the
> latter.  One already exists in the log4j-sandbox tagged as Alpha3.  See
> the article I pointed to in my previous response for details.
> There are caveats and you may find that shared libraries using
> statically defined loggers (e.g., 'static final Logger logger =
> Logger.getLogger("MyLoggerName")') end up logging to a different logger
> repository than you expected.  This occurs because the logger is only
> looked up once, so the logger repository used will be the first one
> looked up.  If one webapp looks it up first, it's logger repository will
> be used for the life of the library (i.e., until server restart).  Other
> apps using the library will have that library's logs going to the first
> application's logger repository.
> I know of no good way around this that I know of.  Maybe Ceki has come
> up with a better way over the years in his work with Logback?  You might
> ask on that mailing list.
> Jake
> On Wed, 31 Mar 2010 10:35:23 +0800
> WM YEOH <spinergywmy@gmail.com> wrote:
>> Hi Jake,
>> Thank you for the article.
>> I tried to put the log4j jar under application classloader level as well
>> as war WEB-INF/lib, and set the delegate to false in sun-web.xml, and
>> that
>> works fine. However, I got class not found exception when came across EJB
>> classes. I even specified the log4j jar in manifest file but no luck.
>> I couldn't find any useful information how to configure sun apps to load
>> parent-last. I am wondering is it no other way to have EJB classes
>> reference
>> log4j? Appreciate if you can again point me to the right direction.
>> Thank you.
>> Regards,
>> Wooi Meng
>> On Mon, Mar 29, 2010 at 10:57 PM, Jacob Kjome <hoju@visi.com> wrote:
>>> Research Logger Repository Selectors. Here's a resource to get you
>>> started....
>>> http://wiki.apache.org/logging-log4j/AppContainerLogging
>>> Jake
>>> On Mon, 29 Mar 2010 17:51:56 +0800
>>> WM YEOH <spinergywmy@gmail.com> wrote:
>>>> Hi there,
>>>> Current setup,
>>>> - App server - Sun Java System Application Server 9.1_01
>>>> - deploy one ear(own war) and another war applications in the same
>>>> stand
>>>> alone instance
>>>> I have setup in a way that each application has its own log4j.xml but
>>>> assign
>>>> to different log files, for instance, log4jA.xml -> A.log and
>>>> log4jB.xml
>>>> ->
>>>> B.log. However, the debug message only written into one log file
>>>> instead
>>>> of
>>>> its designated log file. I could not package the log4j jar into the
>>>> war as
>>>> other classes in separate jar (within ear) used logger. Therefore, I
>>>> have
>>>> to
>>>> specified log4j jar in the server classpath. Which I believed that
>>>> would
>>>> be
>>>> the issue that causing the debug message not written to the correct log
>>>> file.
>>>> I am wondering is there any settings to solve the problem that I
>>>> faced. Or
>>>> is there any alternatives to solve the problem.
>>>> Appreciate anyone help me to solve the problem as soon as possible.
>>>> Please
>>>> let me know if you need further information.
>>>> Thank you.
>>>> Regards

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