JMS distrubuted topic and jms inbound adapter

Question

Hi,
We are building a HA application using precise recovery using JMS. FOr that we want to create a distributed JMS Topic (ckustered JMS Topic). As we understand things, when a JMS subscriber subscribes to a distributed Topic it is actually wired to a sopecific server (a specific fisical JMS Topic). When this JMS server fails the connection is dropped and the JMS subscriber needs to reconnect.
1. Is our understanging correct?
2. If yes and we need to reconnect to the surviving JMS Topic, is there a way to "tell" the JMS Inbound adapter to do so? Is it done automatically by the adapter?
Thanks,

Answer 1

There are a few different things you should be considering when configuring JMS for precise recovery, so I'm afraid this is going to be a long response.
* The precise recovery feature may not work correctly in the case where JMS output messages are lost. Avoiding message loss in the case of a JMS failure involving topics requires the use of persistent messages and durable subscribers. This is true regardless of whether you're using Distributed Topics or a Topic hosted by a single server. So use of durable subscribers is highly recommended when using CEP precise recovery.
* The CEP JMS input adapter won't actually support durable subscriptions until the upcoming 11.1.1.6 (PS5) release. So if you want to use durable subscriptions to avoid problems with precise recovery in the case of JMS server failure you would need to be on this release of CEP (at least for production).
* If you're using the CEP JMS inbound adapter with a distributed topic and a non-durable subscription, you can configure the adapter destination-jndi-name with the logical name of the topic and if the topic member servicing a given consumer fails, the consumer will reconnect to a surviving topic member. This works because you're using a logical destination name (not a physical host name or IP address), so the adapter is able to determine the surviving servers associated with the logical topic and reconnect to one of them. However since you'd be using non-durable subscriptions in this case to achieve failover/reconnect, you can have the problem described above with message loss and precise recovery (non-durable subscribers/non-persistent messaging can lose messages during the actual failover/reconnect).
* Unfortunately, WLS doesn't support durable subscriptions to distributed topics using the logical destination name. When using distributed topics you can only create durable subscriptions on specific topic members, and since these are subscriptions to a specific physical member these subscribers won't failover to another topic member if the server hosting their subscription fails.
So given all of the above you can see that the use of distributed topics with CEP precise recovery may not provide the ideal level of HA (the ability to handle combinations of JMS and CEP failures). You might want to consider using a non-distributed (single server) topic with persistent messaging and durable subscriptions as an alternate approach for precise recovery. In this configuration JMS server failure would require restarting the failed server, but once the JMS server is restarted there should be no message loss and CEP precise recovery should work correctly.
If you're determined to use distributed topics you might want to try posting to the JMS forum to see if anyone there has ideas for other solutions. Just let them know that CEP in this case is essentially acting as a vanilla JMS client (not MDB based) that can't tolerate message loss:
WebLogic Server - JMS