I´ve been developing Entreprise Apps for some time now and I´ve never had any problems to run multiple ears in the same JBoss instance. What i usually do is I add/modify the following code in JBOSS_HOME/server/default/conf/jboss-service.xml:
<mbean code="org.jboss.deployment.EARDeployer" name="jboss.j2ee:service=EARDeployer">
  <attribute name="Isolated">true</attribute>
</mbean>

And in JBOSS_HOME/server/default/deploy/jbossweb-tomcat50.sar/META-INF/jboss-service.xml:

<attribute name="UseJBossWebLoader">false</attribute>

However, I have to use the same jar versions in all apps. Now, I´ve switched to MyEclipse IDE and the EAR structure is a little different since the IDE handles automatically jar versions and all. It deploys fine until I made those changes in the JBoss 3.2.6 configuration. When I change the files above I get the following exception:

java.lang.NoSuchMethodException:
org.jboss.ejb.StatelessSessionContainer.removeHome(javax.ejb.Handle)

I have no idea what that is... when i set UseJBossWebLoader to true, which means that the jboss classloader should override all other jars and the isolated attr is set to false, it deploys fine, but when i try to deploy multiple ears, i get the exception above. I dont have any libs that could compromise the application, just the usual ones that exist in all my other apps:

activation.jar (Impl version 1.0.2)
commons-logging.jar (1.0.2)
commons-beanutils.jar (1.5)
commons-collections.jar (2.1)
commons-digester.jar (1.3)
commons-fileupload.jar
commons-lang.jar (1.0.1)
commons-validator.jar (1.0.2)
jakarta-oro.jar
jaxen-full.jar (1.0 FCS)
jstl.jar (1.1.2)
saxpath.jar (1.0)
standard.jar (1.1.2)
struts-legacy.jar (1.0)
display.jar
iText.jar
jaxb-rt-1.0-ea.jar (1.0-ea)
jaxb-xjc-1.0-ea.jar (1.0-ea)
log4j-1.2.9.jar
mail.jar (1.3.1)
md5.jar
rowset.jar
struts.jar (1.1)
xalan.jar (impl vers. xalan-j_2_5_2)
xercesImpl.jar (Xerces-J_2_3_0)

Is there any jar in the list above that might be conflicting with JBoss 3.2.6?

I have no idea what Im doing wrong, could somebody please help me? Thanks!

Luiz.

Did you ever solve that problem? I have the same trouble now (with v. 4.0.0).
Kind regards Jesper

It had to do with the libraries (.jar files) packaged in my .ear file.

I found the following links that were useful to me.

http://www.jboss.org/wiki/Wiki.jsp?page=ClassLoadingConfiguration

http://www.jboss.org/wiki/Wiki.jsp?page=JBossClassLoadingUseCases

I hope that you find it helpful.