Specifying the version of dependent jar file?

Question

Hi all
At the moment I am fighting with some class loading issues in a J2EE Appcontainer... Acutally the app server uses a different version of a jar file than my application.. Now the classloader always uses
the already loaded classes of the AppServers jar Version instead of those that I want..
I have my application together with the dependent jar packaged together into one jar file... In the manifest I lsit the dependency...
Now my question is if its possible to explicitly state the version of the package that my jar is dependent of...
Any help would be appreciated
regards
tom

Answer 1

Vijay
Acutally I just read through the thread. Actually what I am working on is an J2EE App Containing a couple of EJB (2.0) components in different jars, some utility jars and 2 Wars. All this is packaged together into an ear.
Now Actually the basic structure is like:
Ear
--> WAR1
--> webinf containing classes and manifest with dependent jars
--> War2
--> EJB Jar
--> metinf containing deployment desc and manifest where the manifest references JDom-b10.jar on the classpath
--> Also conatiner JDom-b10.jar
Acutally the JDom.jar is already loaded by the Application Server (Jboss 3.2.3) in its bootstrap loader... I need to have the b10 as otherwise some other 3rd Party stuff of the Ejb is not running...
Now I expected the classloader to prefer the direct deployment unit against all parents and delegating loader... but it doesnt:
15:17:04,011 INFO [STDOUT]
org.jdom.Document(1bb8ea).ClassLoader=org.jboss.system.server.NoAnnotationURLClassLoader@e3b895
..org.jboss.system.server.NoAnnotationURLClassLoader@e3b895
..sun.misc.Launcher$AppClassLoader@e80a59
....file:/C:/Entwicklungstools/jboss-3.2.3_tomcat-4.1.24/bin/
....file:/C:/Entwicklungstools/abaXX/components36/lib/3rdparty/oracle9iR2.jar
....file:/C:/Entwicklungstools/j2sdk_1.4.2_03/lib/tools.jar
....file:/C:/Entwicklungstools/jboss-3.2.3_tomcat-4.1.24/bin/run.jar
..sun.misc.Launcher$ExtClassLoader@1ff5ea7
....file:/C:/Entwicklungstools/j2sdk_1.4.2_03/jre/lib/ext/dnsns.jar
....file:/C:/Entwicklungstools/j2sdk_1.4.2_03/jre/lib/ext/ldapsec.jar
....file:/C:/Entwicklungstools/j2sdk_1.4.2_03/jre/lib/ext/localedata.jar
....file:/C:/Entwicklungstools/j2sdk_1.4.2_03/jre/lib/ext/sunjce_provider.jar
++++CodeSource: (file:/C:/Entwicklungstools/jboss-3.2.3_tomcat-4.1.24/lib/jdom.jar <no certificates>)
Implemented Interfaces:
++interface java.io.Serializable(f62373)
++++ClassLoader: null
++++Null CodeSource
++interface java.lang.Cloneable(13e8d89)
++++ClassLoader: null
++++Null CodeSource
This above is a small JBoss utility acutally printing out the watched URLs of the CL and the Codesource of a class... .. Now actually the classloader shouldn't use the Jdom.jar mentioned as source but the one listed here:
15:16:24,308 INFO [EJBDeployer] nested deployment: file:/C:/Entwicklungstools/jboss-3.2.3_tomcat-4.1.24/server/tebs/tmp/deploy/tmp27652tebs-0.1-SNAPSHOT.e
ar-contents/tebs-migration-0.1-SNAPSHOT.jar-contents/jdom-b10.jar
Actually I think the problem is pretty close to the thread you mentioned before... AFAIK the classloaders in J2EE Containers have to prefer the direct deployment unit (in this case the jar and its content) to any other parent class loaders files... I also thought that there can be mulitple versions of a class file in one VM an that the appserver has to preserve every app from using a class of another app... So that there is some housing principles....
As I could not figure out how to solve this I came to the question regarding versioning... As both JDom.jars contain version information this would solve my probem... But as you already mentioned AFAIK there is only support to give some verision informationen about a jar in the manifest but nothing mentions that you can explicitely request a specific version.
So If anyone has a clou how I get that crapp working I would be very thankful
Tom