In WAS, why TOPIC and QUEUE are used together?

In websphere app server 6.1, when i want to set up JMS, I need to set up a topic, and i need to set up queues and then in MQ explorer I create a subscription between the topic and the queues. Now this configuration is for a publish /subscribe model. If something is published to the topic, all queues will pick up the message.

So how do we do point to point messaging in websphere? I ask this question because I thought topic is for publish subscribe model. And queue is for point to point messaging. But in WAS, the two are mixed up.

The two aren't mixed up. There's no contradiction here, really.

• The publish/subscribe model uses a topic (to which "things" are published), and a set of queues that are set to consume that topic.
• The point-to-point model uses a queue; the "producing" application puts messages in the queue, and the "consuming" application gets messages from that queue.

Therefore, there's no contradiction. Remember, topics and queues are just "tools" to implement publish/subscribe or point-to-point topologies.