> java.lang.ClassNotFoundException: org.jnp.interfaces.MarshalledValuePair
It looks like this class is not in the classpath of your HelloClient program.
Verify that you have all necessary jars in your classpath.
org.jnp.interfaces.MarshalledValuePair is in JBOSS/server/default/lib/jnpserver.jar.
to add jnpserver.jar to the place of jnp-client.jar in the classpath (in the case, or you use jboss and tomcat separately, not when you use tomcat-service).