Redis's pub/sub command

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:

Redis 127.0.0.1:6379> SUBSCRIBE redischatreading messages ... (Press Ctrl-c to quit) 1) "Subscribe" 2) "Redischat" 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.

Redis 127.0.0.1:6379> PUBLISH redischat "Redis is a great Caching technique" (integer) 1redis 127.0.0.1:6379> PUBLISH Redischat "Learn Redis by w3cschool.cn" (integer) # Subscriber will display the following message 1) "Message" 2) "Redischat" 3) "Redis is a great caching Technique "1)" "Message" 2) "Redischat" 3) "Learn Redis by w3cschool.cn"

The Psubscribe command subscribes to one or more channels that match a given pattern. Each pattern takes a * as a match, for example it* matches all channels that start with it (It.news, It.blog, It.tweets, and so on). News.* matches all with news. The first channel (news.it, News.global.today, etc.), and so forth.

Redis 127.0.0.1:6379> psubscribe pattern [pattern ...]

return value
The information received.

Instance
Redis 127.0.0.1:6379> Psubscribe MyChannel
Reading messages ... (Press Ctrl-c to quit)
1) "Psubscribe"
2) "MyChannel"
3) (integer) 1

The Pubsub command is used to view the status of the subscription and publishing system, which consists of several sub-commands in different formats.

Redis 127.0.0.1:6379> PUBSUB <subcommand> [argument [argument ...]

return value
A list of active channels.

Instance
Redis 127.0.0.1:6379> PUBSUB CHANNELS
(empty list or set)

The Publish command is used to send information to the specified channel.

Redis 127.0.0.1:6379> PUBLISH Channel message

return value
The number of subscribers who received the information.

Instance
Redis 127.0.0.1:6379> PUBLISH mychannel "Hello, i m here"
(integer) 1

Iv. The Punsubscribe command is used to unsubscribe from all channels of a given pattern.

Redis 127.0.0.1:6379> Punsubscribe [pattern [pattern ...]]

return value
This command has different performance on different clients.

Instance
Redis 127.0.0.1:6379> Punsubscribe MyChannel
1) "Punsubscribe"
2) "A"
3) (integer) 1

V. The Subscribe command is used to subscribe to information for a given channel or channels.

Redis 127.0.0.1:6379> SUBSCRIBE Channel [channel ...]

return value
Received information

Instance
Redis 127.0.0.1:6379> SUBSCRIBE MyChannel
Reading messages ... (Press Ctrl-c to quit)
1) "Subscribe"
2) "MyChannel"
3) (integer) 1
1) "Message"
2) "MyChannel"
3) "A"

Vi. The unsubscribe command is used to unsubscribe information for a given channel or channels.

Redis 127.0.0.1:6379> unsubscribe Channel [channel ...]

return value
This command has different performance on different clients.

Instance
Redis 127.0.0.1:6379> Unsubscribe MyChannel
1) "Unsubscribe"
2) "A"
3) (integer) 0

Redis's pub/sub command