Redis Publish Subscriptions

A Redis Publish Subscription (PUB/SUB) is a message communication pattern: the Sender (pub) sends a message and the Subscriber (sub) receives the message.

Redis clients can subscribe to any number of channels.

Shows the relationship between channel Channel1 and the three client--client2, CLIENT5, and client1 subscribing to this channel:

When a new message is sent to channel Channel1 via the PUBLISH command, the message is sent to the three clients subscribed to it:

Instance

The following example shows how a publish subscription works. In our example we created a subscription channel named Redischat:

2. Redis 127.0. 0.1:6379> SUBSCRIBE redischat
6. Reading Messages... (press Ctrl-C to quit)
8. 1) "Subscribe"
10. 2) "Redischat"
12. 3) (integer) 1

Now, we re-open a Redis client and then publish two messages on the same channel Redischat, and the Subscriber can receive the message.

2. Redis 127.0. 0.1:6379> PUBLISH redischat "Redis is a great caching technique" /c2>
6. (integer) 1
10. Redis 127.0. 0.1:6379> PUBLISH redischat "Learn Redis by w3cschool.cc"
14. (integer) 1
18. # The subscriber's client will display the following message
20. 1) "message"
22. 2) "Redischat"
24. 3) "Redis is a great caching technique"
26. 1) "message"
28. 2) "Redischat"
30. 3) "Learn Redis by w3cschool.cc"

Redis Publish Subscription commands

The following table lists the common commands for Redis publish subscriptions:

Serial Number	Command and Description
1	Psubscribe pattern [pattern ...] subscribes to one or more channels that match a given pattern.
2	PUBSUB subcommand [argument [argument ...]] View subscription and release system status.
3	The PUBLISH channel message sends information to the specified channel.
4	Punsubscribe [pattern [pattern ...]] unsubscribe from all channels of a given pattern.
5	SUBSCRIBE Channel [Channel ...] subscribe to the information given for one or more channels.
6	unsubscribe [Channel [channel ...]] means to unsubscribe from a given channel.

Redis Publish Subscriptions