Pulsar订阅模式类型SubscriptionType

Posted 2022-11-23 抓手

 Pulsar订阅模式类型SubscriptionType枚举源码

public enum SubscriptionType 
    /**
     * There can be only 1 consumer on the same topic with the same subscription name.
     */
    Exclusive,

    /**
     * Multiple consumer will be able to use the same subscription name and the messages will be dispatched
     * according to a round-robin rotation between the connected consumers.
     *
     * <p>In this mode, the consumption order is not guaranteed.
     */
    Shared,

    /**
     * Multiple consumer will be able to use the same subscription name but only 1 consumer will receive the messages.
     * If that consumer disconnects, one of the other connected consumers will start receiving messages.
     *
     * <p>In failover mode, the consumption ordering is guaranteed.
     *
     * <p>In case of partitioned topics, the ordering is guaranteed on a per-partition basis.
     * The partitions assignments will be split across the available consumers. On each partition,
     * at most one consumer will be active at a given point in time.
     */
    Failover,

    /**
     * Multiple consumer will be able to use the same subscription and all messages with the same key
     * will be dispatched to only one consumer.
     *
     * <p>Use ordering_key to overwrite the message key for message ordering.
     */
    Key_Shared

独占模式（Exclusive）

只允许有一个Consumer加入Subscription ，有其他Consumer试图订阅都会报错，如果该Consumer出现故障了就会停止消费。
Pulsar默认是独占模式（Exclusive）。

共享模式（Shared）

允许多个Consumer加入同一个Subscription，如果Consumer连接异常，就由其他Consumer来接受消息。

灾备模式（Failover）

当存在多个Consumer时，按字典顺序排序，第一个Consumer被初始化为唯一接受消息的消费者。当第一个Consumer断开时，所有被发送给他，但没有被确认的消息将会被分发给队列中的下一个Consumer。

KEY共享模式（Key_Shared）

当存在多个Consumer时，根据消息的key进行分发，key相同的消息只会被分发到同一个消费者。