DurableSubscribers

Question

Hi All,
I am creating DurableSubscribers on a remote JMS topic. Here code snippet
public void connect(){
tcf = new STCTopicConnectionFactory(RibHost, rib_port);
          topicConnection = tcf.createTopicConnection();
          logger.debug(" topicConnection Created "+topicConnection);
          //Stop the connection if
          topicSession = topicConnection.createTopicSession(false,
          Session.AUTO_ACKNOWLEDGE);
          logger.debug(" TopicSession Created "+topicSession);
//           temporarly stop the connection for incomiing messages
          if(topicConnection!=null)topicConnection.stop();
          topic = topicSession.createTopic(TMP_PRC_TOPIC);
          logger.debug("Topic Created >>>>> "+topic);
          try{
               topicSubscriber = topicSession.createDurableSubscriber(topic, "SH_CLR_PRC_CHG");
          }catch(Exception e){
               System.out.println(" Exception Creating DurableSubscriber SH_CLR_PRC_CHG "+e.getMessage());
          logger.debug("Subscriber Created >>>>> "+topicSubscriber);
          topicSubscriber.setMessageListener(this);
          topicConnection.setExceptionListener(this);
          topicConnection.start();
Topic being created on subscription name SH_CLR_PRC_CHG and messages are comming. But When i restart my application,
1) If no messages are there on the subsction in remote jms server, the connection is created fine
2) If there are some messages are already in the subscription, the connection() throws exception saying the subsctiption already exists.
How do solve this problem. Before the creating topicSession.createDurableSubscriber(), is there any way i can check if the subsription name exists or not
Any advises please?

Answer 1

Well Aoifek this is how well i have understood things...
For the first question no... There is no such tool available with JMS
For the second one.....Client ids and durable subscriber names are essential in one way. PubSub domain with normal subscribers can work i.e receive messages provided only when the TopicSubscriber is active. Since it has this limitation maybe on creating a durable subscriber using createDurableSubscriber() the status of the created TopicSubscriber is maintianed by the provider so that any messages to the Topic with which this TopicSubscriber is associated to can receive the messages... I know this is not convincing but .... i have convinced myself with this explaination i got from someone.....
Well as per the reference implementation this setting of clientid should throw InvalidClientID exception.... and as for the duplicate messages received... i am too having the same problem... the behaviour is very ambigouous....
if any new findings please let me know...
Thanks