Jboss 4.0.4 has some feature which allows web service clients to be "deployed" into the container without too many hassles (See this).

That is apparently controlled by client-deployer-service.xml.

Now, here is something weird : I had an ear file that used to deploy fine under jboss-4.0.3. After upgrading to jboss 4.0.4 GA1, I get the following exception.

14:14:14,900 INFO  [EjbModule] Deploying FooBarBean
14:14:15,209 INFO  [EjbModule] Deploying BazHibernateSequenceBean
14:14:16,439 ERROR [XmlFileLoader] XmlFileLoader: File META-INF/application-client.xml process error. Line: 3. Error message: The content of element type "application-client" is incomplete, it must match "(icon?,display-name,description?,env-entry*,ejb-ref*,resource-ref*)".
14:14:16,440 ERROR [MainDeployer] Could not start deployment: file:/home/xxx/tools/java/jboss-4.0.4.GA/server/default/tmp/deploy/tmp19686xxx.ear-contents/my-module.jar
org.jboss.deployment.DeploymentException: Invalid XML: file=META-INF/application-client.xml; - nested throwable: (org.xml.sax.SAXParseException: The content of element type "application-client" is incomplete, it must match "(icon?,display-name,description?,env-entry*,ejb-ref*,resource-ref*)".)
        at org.jboss.metadata.XmlFileLoader.getDocument(XmlFileLoader.java:331)
        at org.jboss.metadata.XmlFileLoader.getDocument(XmlFileLoader.java:272)
        at org.jboss.deployment.ClientDeployer.start(ClientDeployer.java:143)

Initially I thought it had something to do with web services being exported by my ear file etc. but apparently it was this client deployer service that was causing the problem.

I simply removed the client deployer service (client-deployer-service.xml) from server/default/deploy directory : and the problem went away.