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From Ceki Gülcü <>
Subject RE: [ApacheDS] JBoss compatibility?
Date Fri, 24 Feb 2006 16:44:42 GMT
At 04:49 PM 2/24/2006, Endi S. Dewata wrote:
>Hi Ceki,
> > Which version of NLOG4J and ApacheDS are you using? Versions of NLOG4J
> > prior to 1.2.16 did indeed have a runtime compatibility issue with log4j.
> > However, NLOG4J version 1.2.16 and later should not suffer from the
> > problem you describe. Thus, it is important to know the version of
> > ApacheDS and NLOG4j that you are using.
>I'm checking out the latest ApacheDS (version 1.0 RC1) from the svn trunk,
>the apacheds/core/pom.xml says that it's using nlog4j version 1.2.19.
>I also downloaded JBoss 4.0.3 SP1 source code, and there is a log4j.jar file
>in thirdparty/apache-log4j/lib directory which should be version 1.2.8
>according to component-info.xml.
>So I tried compiling a small program using Log4j API:
>   import org.apache.log4j.*;
>   public class Test {
>       public static void main(String args[]) {
>           Logger log = Logger.getLogger(Test.class);
>           log.debug("Test");
>       }
>   }
>I compiled it with nlog4j-1.2.19.jar, then I tried to run it with log4j.jar
>from JBoss, then I got this error:
>Exception in thread "main" java.lang.NoSuchMethodError:
>It looks like the nlog4j has a debug(String) but the log4j doesn't.
>I also tried the following program using SLF4J API:
>   import org.slf4j.*;
>   public class Test {
>       public static void main(String args[]) {
>           Logger log = LoggerFactory.getLogger(Test.class);
>           log.debug("Test");
>       }
>   }
>I compiled it with nlog4j-1.2.19.jar, then I tried running it with log4j.jar
>and nlog4j-1.2.19.jar in the class path in this order, then I got this
>   Exception in thread "main" java.lang.IncompatibleClassChangeError
>The error also occurs when executing log.debug(...) statement.
>If I reverse the order of the jar files, it will work fine because nlog4j
>will be loaded first. However in JBoss this is not possible because JBoss
>classes will be loaded first before the SAR files. Any suggestions? Thank
>you very much.


I think your description of the problem is quite valuable.

Compilation against NLOG4J is sticky, in the sense that you cannot later 
revert back to log4j. However, I think that this is not the problem you are 
facing. As far as I know ApacheDS does not invoke log4j directly, it 
invokes the SLF4J API instead. From what you describe, the mere presence of 
log4j in JBoss' class loader path, messes up SLF4J's NLOG4J binding.

As an immediate fix, you can just replace JBoss' copy of log4j with NLOG4J. 
This should fix the problem as far as you are concerned. Another perhaps 
better solution, is to replace nlog4j.jar which ships with ApacheDS with 
slf4j-log4j12.jar without replacing any jar files in JBoss. FYI, 
slf4j-log4j12.jar ships with the SLF4J distribution.

I guess that this should be added to ApacheDS documentation in order to 
avoid similar inconveniences to other JBoss+ApacheDS users. Maybe that is 
already the case?

>Endi S. Dewata

Ceki Gülcü

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