Websocket (WS) cluster solution

WebSocket(ws) Clustering solutions

1： Preface

In a particular scenario , It is necessary to realize the purpose that the server actively pushes data to the client , Now ws It's coming out. . The following model

however This kind of existence, this single point problem , So how to solve this single point problem , It's simple , We go straight through nginx Just configure the cluster , as follows （nginx It's supporting ws Clustered ）

The configuration is as follows

 map $http_upgrade $connection_upgrade {
    
    default upgrade;
    '' close;
  }

2： problem

Now the project has been deployed , Is there a problem ？ Next, let's analyze

because Load balancing Why , The following may occur

client1 adopt http Request server A, Then you need the server to pass ws Push data to client2, But at this point ,client2 Connected to another server B, Due to server A and client2 There is no maintenance between ws, So the data cannot pass through the server A Push to client2 Of , Or through the server B Push the data over , We need a bridge to connect , Let the server B Know you want to push data to client2

3： Solutions

3.1：jvm Communication problems between

By what means can we achieve notification ,http？tcp？ Or something like a message queue

3.2： Convention on data format of communication

stay jvm Data transmission before ,jvm2 Received on jvm1 When the data in , You should agree on a data format （ agreement ）, How to analyze , How to send , The message sent specifies the machine name , To every one. jvm Match a message queue

{
    "to":"serverB",
 "data": " How are you? ~"
}

3.3：client2 Which server to connect to

Can pass client2 When connecting to the server redis Go and get a registry ,<client2, jvmName>

3.4：client2 Is it in me http On the requested machine

Can pass client2 When connecting to the server, at present jvm Add a key value pair to the cache <client2, wsclient>

3.5： Overall flow chart

4： summary

If you can't solve the problem in a certain dimension , Can we go up a dimension to think , Generally speaking, it is OK , Many problems are solved in this way , For example, the classic distributed lock , It is solved through dimension upgrading .