MQTT 共享订阅
MQTT shared subscription
使用 MQTT 共享订阅，有关订阅主题的消息只会发送给 一个 订阅客户端。那么，同组的其他客户端也订阅了同一个主题，如何接收消息呢？
With a MQTT shared subscription, the message on the subscribed topic would only be sent to one of the subscribing clients.
正确。对于正常的（non‑shared) subscription the messages are sent to ALL subscribers; with shared 订阅，它们将发送给一个订阅者。
在引入共享订阅之前，很难处理需要多个服务器（用于容错、负载平衡等）但只想处理每条消息一次的情况。共享订阅提供了一种实现此目的的简单方法。
Then, how the other clients of the group receive the message as they also subscribe to the same topic?
如果他们订阅相同的共享订阅（具有相同的 ShareName），则只有一个人会收到消息；这是设计使然。如果您希望他们都收到消息，请不要使用共享订阅。或者，您可以根据 the spec:
建立多个订阅（这样所有订阅者都会收到消息，但只有一个订阅者会处理它 - 但请注意“可以”）
If a Client has a Shared Subscription and a Non‑shared Subscription and a message matches both of them, the Client will receive a copy of the message by virtue of it having the Non‑shared Subscription. A second copy of the message will be delivered to one of the subscribers to the Shared Subscription, and this could result in a second copy being sent to this Client.
使用 MQTT 共享订阅，有关订阅主题的消息只会发送给 一个 订阅客户端。那么，同组的其他客户端也订阅了同一个主题，如何接收消息呢？
With a MQTT shared subscription, the message on the subscribed topic would only be sent to one of the subscribing clients.
正确。对于正常的（non‑shared) subscription the messages are sent to ALL subscribers; with shared 订阅，它们将发送给一个订阅者。
在引入共享订阅之前，很难处理需要多个服务器（用于容错、负载平衡等）但只想处理每条消息一次的情况。共享订阅提供了一种实现此目的的简单方法。
Then, how the other clients of the group receive the message as they also subscribe to the same topic?
如果他们订阅相同的共享订阅（具有相同的 ShareName），则只有一个人会收到消息；这是设计使然。如果您希望他们都收到消息，请不要使用共享订阅。或者，您可以根据 the spec:
If a Client has a Shared Subscription and a Non‑shared Subscription and a message matches both of them, the Client will receive a copy of the message by virtue of it having the Non‑shared Subscription. A second copy of the message will be delivered to one of the subscribers to the Shared Subscription, and this could result in a second copy being sent to this Client.