Reconnect Websocket after connection loss

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Reconnect Websocket after connection loss

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#1 by (3 votes)

1

I use this code to connect to my server with WebSockets :

(function(nameSpace) {
  function createMethod(method, options, stateCallback) {
    var that = this;
    this[method] = function() {
      if (stateCallback && stateCallback.apply) {
        stateCallback(method);
      }
      console.info(method);
      if (options[method] && options[method].apply) {
        options[method].apply(that, arguments);
      }
    };
  }

  function SocketWrapper(options) {
    var ws,
      events = ['onopen', 'onmessage', 'onclose', 'onerror'],
      i, len, prop = {
        opened: false,
        closed: false,
        error: false
      },
      method;

    if (typeof options === 'undefined' || !options) {
      throw 'ArgumentException: please add default constructor options';
    }

    this.queue = [];

    this.onEventTrigger = function(eventName) {
      var i, len;
      if (eventName === 'onopen') {
        prop.opened = true;
        prop.closed = false;
        // openend send queue
        if (this.queue.length > 0) {
          for (i = this.queue.length; --i >= 0;) {
            this.send.apply(this, this.queue[0]);
            this.queue.splice(0, 1);
          }
        }
      }
      if (eventName === 'onerror') {
        prop.error = true;
      }
      if (eventName === 'onclosed') {
        prop.opened = false;
        prop.closed = true;
      }
    };

    this.init = function() {
      var cb = this.onEventTrigger.bind(this);
      ws = new WebSocket(options.url);

      for (i = 0; i < events.length; i++) {
        method = events[i];
        createMethod.apply(ws, [method, options, cb]);
      }
    };

    this.send = function() {
      if (prop.closed) {
        throw 'InvalidOperation: Cannot send messages to a closed Websocket!';
      }
      if (!prop.opened) {
        this.queue.push(arguments);
      } else {
        ws.send.apply(ws, arguments);
      }
    };

    this.init();
    return this;
  }

  window.SocketWrapper = SocketWrapper;
}(window));

var socket = new window.SocketWrapper({
  url: 'ws://127.0.0.1:1805',
  onopen: function() {
    this.send('message', 'hi');
  },
  onmessage: function() {
    console.log(arguments);
  },
  onclose: function() {
    socket = null;
  },
  onerror: function() {
    console.log('error occured, oh no!');
    console.error(arguments);
  }
});
socket.send('i am message send to soon, but since i check the state of the ws object, i will be queued and send when appropriate');

This code suits me, it was the solution that I found for my case, but I wanted it to reconnect as soon as the connection was lost, it would try to reconnect until I can. I do not know much how to adapt because it is not mine , how to proceed?

javascript websocket

asked by anonymous 20.03.2015 / 23:01

1 answer

Select field not empty How to get the name of the parent object of the Javascript property

score 3 · Accepted Answer

When the connection is lost the event onclose is triggered, to reconnect you must work on that event.

One way you can use to connect again is through the setTimeout , it will perform an action every n seconds.

Instead of declaring the variable socket with all that code, do this in a function:

function CreateSocketWrapper(){
    return new window.SocketWrapper({
      url: 'ws://127.0.0.1:1805',
      onopen: function() {
        this.send('message', 'hi');
      },
      onmessage: function() {
        console.log(arguments);
      },
      onclose: function() {
        setTimeout(function(){CreateSocketWrapper()}, 5000); // 5 segundos
      },
      onerror: function() {
        console.log('error occured, oh no!');
        console.error(arguments);
      }
    });
}

And to use it:

var socket = CreateSocketWrapper();
socket.send('i am message send to soon, but since i check the state of...');