Publish and subscribe

• Publishing and subscribing are a message communication pattern.
• Pros: Reduce the coupling between the message subscriber and the message Publisher, similar to the Observer pattern in design mode.
• Publications and subscriptions for Redis

Publish and subscribe

The commands for subscribing are as follows:

// subscribe to one or more channels Subscribe  channel1  channel2  channel3 ... // mode subscription, channel parameters similar to regular expressions psubscribe abc*  xyz* ...  

The Publish command is as follows:

Publish Channel MSG

Start a Subscriber client X

subscription Cctv-1 returns three parameters: Subscribe subscription succeeded, The subscribed channel is Cctv-1, the number of channels currently subscribed is 1;

Subscription Cctv-2 returns three parameters: Subscribe subscription is successful, the subscribed channel is Cctv-2 and the number of channels currently subscribed is 2.

Start a Subscriber client Y

Subscription cctv-* returns three parameters: Psubcribe subscription succeeded, subscribed channel cctv-*, number of channels subscribed by current client 1.

Start a publisher client, Publish channel Cctv-1 message

Subscriber Client X receives subscription information, returns three parameters: Received message success, channel, received message

Subscriber Client Y receives subscription information, returns four parameters: Received message success, mode subscription channel, received message channel, received message

Cancel Subscription

Unsubscribe  cctv-1punsubscribe  CCTV-*

The unsubscribe is not emulated on the official client.

View Subscriptions

// View all channels subscribed to pubsub  channels;pubsub  channels  msg*; // View the number of subscribers to this channel pubsub  numsub  channel1 channel2 ...;

• Programming to showcase Redis publications and subscriptions

1  Public classMySubextendsjedispubsub{2 3 @Override4      Public voidonMessage (String channel, String msg) {5System.out.println ("onMessage-" + Channel + "-" +msg);6     }7 8 @Override9      Public voidonpmessage (string pattern, string channel, String msg) {TenSystem.out.println ("onpmessage-" + Pattern + "-" + Channel + "-" +msg); One     } A  - @Override -      Public voidOnpsubscribe (String Channel,intmsg) { theSystem.out.println ("Onpsubscribe-" + Channel + "-" +msg); -     } -  - @Override +      Public voidOnpunsubscribe (String arg0,intarg1) {} -  + @Override A      Public voidOnsubscribe (String Channel,intNumber ) { atSystem.out.println ("Onsubscribe-" + Channel + "-" +Number ); -          -     } -  - @Override -      Public voidOnunsubscribe (String arg0,intarg1) {} in}

Subscriber Client A

 1  public  class   subclient { 2  public  static  void   main (string[] args) { 3  mysub sub = new   mysub ();  4  Jedis Jedis = new  Jedis ("127.0.0.1", 6 379 5  jedis.subscribe (Sub, "Cctv-1"  6   7  }

subscriber client B (modal subscription)

 1  public  class   Psubclient { public  static  void   main (string[] args) { 3  mysub sub = new   mysub ();  4  Jedis Jedis = new  Jedis ("127.0.0.1", 6 379 5  jedis.psubscribe (Sub, "cctv*"  6   7  }

Publisher Client C

1  Public class pubclient {2      Public Static void Main (string[] args) {3         New Jedis ("127.0.0.1", 6379); 4         Jedis.publish ("Cctv-1", "Hello,this is Cctv-1"); 5     }6 }

Run client ABC in turn

A-Terminal output

Onsubscribe-cctv-1-1onmessage-cctv-1-Hello,this is Cctv-1

B-Terminal output

onpsubscribe-cctv*-1onpmessage-cctv*-Cctv-1-Hello,this is Cctv-1

Learn more and remember more.

Publish and subscribe