I have figured the root of the problem for both the issues. in case if this helps some newbie with the same kind of trouble im posting the solution here.
First thing is every time I ran the client, Jboss is treating the durable subscriber as from a new client, so in reality we need to create one durable subscriber, and this subscriber can be re-used any number of times(creating it and closing it) in the same run. and this solved the other problem too.
I am working on jboss publisher - durable subscribers . I made the necessary configuration . Able to publish messages succesfully to topic but the subscriber fails to read the messages. Could you please provide more information on this?
If I use the same client id more than once , I am being thrown with Client Id already exists.