Publish/Subscribe (Pub/Sub) Messaging

A messaging pattern in which publishers send messages to a topic without knowing the receivers, and every subscriber to the topic gets a copy. It decouples senders from receivers and supports fan-out.

In a queue each message is typically consumed by one worker, while in pub/sub each subscriber gets its own copy. Many products combine both, for example by attaching a queue to each subscriber. See the Message Queue Software page.

No. Redis documents Pub/Sub as channel-based delivery without persistence, so subscribers miss messages sent while they are offline. Redis Streams, Kafka or a managed service with retention suit durable needs.

Choose a managed service in your cloud when possible, such as Google Pub/Sub, Amazon SNS with SQS, or Azure Event Grid. Use MQTT brokers such as EMQX or HiveMQ for devices, Kafka or Pulsar for retained event streams, and Ably, Pusher or Centrifugo for browser and mobile clients.

MQTT is a lightweight publish/subscribe protocol designed for constrained devices and unreliable networks, while AMQP is a richer messaging protocol with queues and exchanges used by brokers such as RabbitMQ.

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