CODEWITHSUNDEEP
node.jssocketswebsocketsocket.iochat
Bitsian
Bitsian

Reputation: 2258

How to make the client disconnect immediately on network loss in socket.io?

I am developing a chat application using socket.io for iOS app and androdi app. And the issue am facing is when network connection is suddenly lost on client, it takes 25 secs(default heartbeat interval) for the disconnect event on the socket.io server to get called. I am removing the socket.id/username from my db when the disconnect event is called. But since during this 25 secs the socket.id/username still exists on my db, when some other user sends a message to this user who lost network connection, it will be shown as sent even though it was never delivered. The solution would probably be to reduce the Heartbeat interval to maybe 1 or 2 secs. I have tried that but strangely its not being set, it still takes 25 secs approx. Below is my code

var app = require('express')()
 , server = require('http').createServer(app)
 , sio = require('socket.io')
 , redis = require('redis');

var client = redis.createClient();
var io = sio.listen(server, { origins: '*:*' });

io.set("store", new sio.RedisStore);

io.set("heartbeat interval", 2);    

var azure = require('azure');

server.listen(4002);

But even if i get the heartbeat interval set to 2secs, i think there might be a downside to it. If the mobile apps send acknowledgement to the server's heartbeat every 2secs then taht would probably drain the app's battery if the app is left idle for a long time. So I would appreciate any solutions at all that would work best in my case.

Thanks

Upvotes: 1

Views: 1098

Answers (1)

Gntem
Gntem

Reputation: 7165

there are many variables to consider, when to disconnect a client , since 25secs is a way to small interval to check something especially if you application has say 100.000 users.

Things you could try

  • client side control, to see if a user is typing or even touching the device to get user status idle|active|zombie.

  • don't remove user from redis, immediately after client emit disconnect, instead you could place the user , into a toDisconnect queue list, or set an additional variable, if the same user is connected again then you can simply move the object, instead of querying again for creating the object.

  • if still not satisfied with result, try binary websockets, at least it will remove some overhead from packets and they will be delivered a bit faster, since the size is a smaller.

  • bottom line, don't rely on redis, you could easily remove it from structure, and apply a custom websocket server, and all user management build in node.js

Upvotes: 1

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