Is there any way to handle websocket onmessage handler just like done method handlers attached to XHR deferred objects in jQuery

Question

I'm currently doing this hack to handle the websocket's onmessage.

$scope.wsCon.onMessage = function(result) {
    $scope.wsCon.trigger(result.handler, result.data);
};

Problem here is that, onmessage is handling all the incoming requests through websocket.

But I need something like this:

$scope.wsCon.
    .send(data)
    .done(data, function (result) {
        // Deal with the result here
    })
    .fail(data, function() {
        // Show the error message
    })
    .complete(data, function() {
        // Do this always
    });

I know this is not achievable in websocket on single connection. But still, is there any way to produce effect something like the way jQuery does?

You just need a function that relates every answer to the request that triggered it. Then you can resolve your deferred with it. — Bergi, Feb 20 '15 at 09:22
Currently I'm doing the same thing right? I'm sending the handler name in send function like this: send({data:"", handler:"handlerName"}); — Sandesh Damkondwar, Feb 20 '15 at 09:31

score 1 · Accepted Answer · edited May 23 '17 at 12:10

WebSockets are not request/response based, so since there is no response required when you send a message, what do you expect to happen to finish that promise? the socket flushing the buffer? :) If the browser fails to send the message because the socket is dead, you will get an "onerror" message.

If you need confirmation of the message, or awaiting a response, you need to implement it yourself.

Please take a look at this answer : AngularJS and WebSockets beyond About this $connection service declared in this WebSocket based AngularJS application

Basically it is an example about creating a WebSocket service in AngularJS that can be used to request/response and publish/subscribe.

Basically you can listen for messages:

   $connection.listen(function (msg) { return msg.type == "CreatedTerminalEvent"; }, 
        function (msg) {
            addTerminal(msg);
            $scope.$$phase || $scope.$apply();
   });

Listen once (great for request/response):

$connection.listenOnce(function (data) {
    return data.correlationId && data.correlationId == crrId;
}).then(function (data) {
    $rootScope.addAlert({ msg: "Console " + data.terminalType + " created", type: "success" });
});

And send messages:

$connection.send({
    type: "TerminalInputRequest",
    input: cmd,
    terminalId: $scope.terminalId,
    correlationId: $connection.nextCorrelationId()
});

Is there any way to handle websocket onmessage handler just like done method handlers attached to XHR deferred objects in jQuery

1 Answers1