Integration / ActiveMQ Interview Questions Basics
What is a Durable Subscriber in ActiveMQ?
A Durable Subscriber is a Topic consumer that registers with a unique client ID and subscription name so the broker retains messages for it even while it is disconnected.
Regular topic subscribers only receive messages published while they are actively connected; a durable subscriber, by contrast, catches up on everything sent during its downtime once it reconnects. This is useful when a subscriber must never miss an event, such as an audit or billing service listening to a notifications topic.
Only one active connection may use a given durable subscription at a time, so restarting a durable subscriber client with the same identifiers simply resumes the same backlog rather than creating a second parallel subscription.
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