Integration / Apache Pulsar Interview questions
When should you use a Reader instead of a Consumer?
Use a Reader when you need direct, explicit control over the starting read position in a topic - for example replaying from a specific message ID or from the very beginning - without the subscription-based cursor tracking a Consumer relies on.
A Reader doesn't create a durable, named subscription that persists across restarts; it simply starts reading from wherever you tell it to (earliest, latest, or a specific message ID) each time it connects, which suits stateless replay tools or one-off inspection scripts.
A Consumer, by contrast, is the right choice for typical application workloads where you want Pulsar to durably track progress on your behalf so processing can resume exactly where it left off after a restart.
A Reader differs from a Consumer mainly by:
A Reader is well suited to:
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