Publish/Subscribe vs Producer/Consumer?

Question

From messaging point of view with systems like Kafka, RabbitMQ, HornetQ, ActiveMQ, etc. is there a difference between pub/sub and prod/con or are they used interchangeably?

Answer 1

There is a difference between the publish/subscribe and producer/consumer models.

Publish/Subscribe : Subscribers subscribe to the publisher. Each message the Publisher publishes is sent to all the subscribers. That is, all subscribers receive the same message. (Think of a newspaper or magazine subscription. All subscribers receive the same magazine or newspaper)

Producer/Consumer : Each message the producer produces will be consumed by a single consumer. This is a mechanism to distribute the work load to multiple consumers. (Think of the several cash registers at the supermarket. Each customer goes to a single cash register. The customers are like the messages that are produced and the cash registers are the consumers)

Answer 2

In producer consumer , message produced by producer is only consumed by one consumers . Even with n number of consumers each message will be consumed by only one consumer . Producing n messages to n consumers , each message will be produced by one consumer (round robin algorithm) .

In contrast in Publisher subscriber , message produced by publisher is consumed by all subscribers that have subscribed to specific queue . Publishers produce messages while subscriber consumes message . Messages are posted in subscription queue .

Answer 3

As per my understanding - Prod/Consu - Producer produces and Consumer consumes the produced task . - Publisher/Subscriber - Publisher produces and Subscriber consumes the produced task only if Subscriber is subscribed to Publisher.

Both can be interchanged but the later one makes sense in terms of Architectural real use cases .Produce and publish only if it is subscribed based upon subscription agreement .

Thanks