JMS Topic vs Queues

Question

That means a topic is appropriate. A queue means a message goes to one and only one possible subscriber. A topic goes to each and every subscriber.

Topics are for the publisher-subscriber model, while queues are for point-to-point.

It is simple as that:

Queues = Insert > Withdraw (send to single subscriber) 1:1

Topics = Insert > Broadcast (send to all subscribers) 1:n

A JMS topic is the type of destination in a 1-to-many model of distribution. The same published message is received by all consuming subscribers. You can also call this the 'broadcast' model. You can think of a topic as the equivalent of a Subject in an Observer design pattern for distributed computing. Some JMS providers efficiently choose to implement this as UDP instead of TCP. For topic's the message delivery is 'fire-and-forget' - if no one listens, the message just disappears. If that's not what you want, you can use 'durable subscriptions'.

A JMS queue is a 1-to-1 destination of messages. The message is received by only one of the consuming receivers (please note: consistently using subscribers for 'topic client's and receivers for queue client's avoids confusion). Messages sent to a queue are stored on disk or memory until someone picks it up or it expires. So queues (and durable subscriptions) need some active storage management, you need to think about slow consumers.

In most environments, I would argue, topics are the better choice because you can always add additional components without having to change the architecture. Added components could be monitoring, logging, analytics, etc. You never know at the beginning of the project what the requirements will be like in 1 year, 5 years, 10 years. Change is inevitable, embrace it :-)

Queues

Pros

• Simple messaging pattern with a transparent communication flow
• Messages can be recovered by putting them back on the queue

Cons

• Only one consumer can get the message
• Implies a coupling between producer and consumer as it’s an one-to-one relation

Topics

Pros

• Multiple consumers can get a message
• Decoupling between producer and consumers (publish-and-subscribe pattern)

Cons

• More complicated communication flow
• A message cannot be recovered for a single listener