Choosing a Message Broker: Queue, Topic, or Log Defines Your Delivery Contract

Many teams pick a messaging broker based mainly on throughput or cost, but the real decision is about contracts: who owns a message after delivery, how consumer progress is tracked, and whether past events remain available. Queues delete messages once consumed and suit competing workers, topics fan out copies to each subscription, and logs retain events so consumers can replay them by rewinding offsets. Failure handling also differs, since a failing message in a log can stall its partition unless retry mechanisms are built manually. Cloud services map to these primitives differently, for example SNS and Azure Service Bus topics behave unlike each other, and the article recommends publishing once to a topic with a dedicated queue per consumer for isolation.