Redis publishes subscriptions

Redis publishes subscriptions

Redis publishing subscriptions (pub/sub) are a mode of message communication: the sender (pub) sends a message and the subscriber (sub) receives the message.

The Redis client can subscribe to any number of channels.

The following illustration shows the relationship between channel 1 and the three clients that subscribe to the channel - client2, client5, and client1:

When a new message is sent to channel 1 via the PUBLISH command, the message is sent to the three clients that subscribe to it:

The following example shows how a publishing subscription works. In our example, we created a subscription channel called redisChat :

redis 127.0.0.1:6379> SUBSCRIBE redisChat

Reading messages... (press Ctrl-C to quit)
1) "subscribe"
2) "redisChat"
3) (integer) 1

Now, let's re-open the redis client, and then publish the message twice on the same channel, redisChat, and the subscriber will receive the message.

redis 127.0.0.1:6379> PUBLISH redisChat "Redis is a great caching technique"

(integer) 1

redis 127.0.0.1:6379> PUBLISH redisChat "Learn redis by w3cschool.cn"

(integer) 1

# 订阅者的客户端会显示如下消息
1) "message"
2) "redisChat"
3) "Redis is a great caching technique"
1) "message"
2) "redisChat"
3) "Learn redis by w3cschool.cn"

Redis publishes subscription commands

The following table lists common commands for redis publishing subscriptions: