Subscriptions in Pulsar
Subscriptions in Pulsar describe which consumers are consuming data from a topic and how they want to consume that data.
Subscription metadata
Subscriptions are managed in the broker as a collection of metadata about a topic and its subscribed consumers. This metadata includes:
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Topic name: The topic the consumer wants data from
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Subscription name: A string representing a qualified name for the subscription
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Subscription type: The type of subscription being used
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Subscription cursor: A representation of the consumer’s current place in the subscribed topic log
For example, the Pulsar consumer below has a Shared subscription to my-topic that starts at the Earliest cursor position in my-subscription:
pulsarConsumer = pulsarClient.newConsumer(Schema.BYTES)
.topic("my-topic")
.subscriptionName("my-subscription")
.subscriptionType(SubscriptionType.Shared)
.subscriptionInitialPosition(SubscriptionInitialPosition.Earliest)
.subscribe();