Control io heartbeat interval and timeout via server configuration

[vstirbu]

I would like to be able to configure the interval and the timeout of the underlying socket.io to accommodate scenarios with stricter requirements than the default values.

I have noticed that there is an undocumented configuration option logLevel that allows controlling the socket.io logging behaviour: https://github.com/incompl/cloak/blob/master/src/server/cloak/index.js#L93

However, I have noticed also #69 where the idea is not to have socket.io specific configurations.

So, what do you say about extending the server configuration with socket.io specific parameters, although heartbeat is not particularly tight to the specific transport...

My quick and dirty proposal is to add

io.set('heartbeat interval', config.heartbeatInterval);
io.set('heartbeat timeout', config.heartbeatTimeout);

right after logLevel.

[incompl]

Does it work to do this?

cloak.run('http://localhost:8090', {
  'socket.io': {
    'heartbeat interval': 123,
    'heartbeat timeout', 456
  }
});

If so, I will update the documentation at https://github.com/incompl/cloak/wiki/ClientConfiguration accordingly.

[vstirbu]

The option for controlling the heartbeat on the client that I found in the socket.io documentation that works with cloak is the following:

cloak.run(url, {
   'socket.io': {
      heartbeatTimeout: 10000 // the value in ms
   }
});

However I'm not that familiar with how socket.io handles the heartbeat and if you can control the server behaviour from the client.

[incompl]

I'm not clear on the details (seems like heartbeat settings are not in the latest version of Socket.io so they weren't in the documentation anymore) but I found this on Stackoverflow:

By default, a Socket.IO client will send a heartbeat to the server every 15 seconds (heartbeat timeout), and if the server hasn't heard from the client in 20 seconds (heartbeat interval) it will consider the client disconnected.

[vstirbu]

There is also this in the documentation on migrating to 1.x.

BTW, I have this branch with cloak running over socket.io 1.x, but don't know yet how to handle the heartbeat issue before making a PR.

[incompl]

Implemented by #88