A little bit more informations.
It seems that the class loader does not find the org.jboss.ws.core.soap.SOAPHeaderImpl class when the code is in a JAR file deployed in the webapp.
When code is directly in a class of the web app, the class loader find the SOAPHeaderImpl...
Another strange thing is that we do not have ClassNotFoundException or NoClassDefFoundError. The app "seems" to search for the class and memory grow slowly until crashing.
A last information, when searching for the class, we have found it under the jboss-5.1.0.GA\client folder in the jbossws-native-core.jar file.
So can it be possible that a class in the webapp is able to get the library that comes from the client folder of the server ? And not a JAR in this same webapp ?
Do we have a design issue ?
Another thing ?
Thanks a lot for your help !