CODEWITHSUNDEEP
node.jswebsocketipc
Kamil Jaśkiewicz
Kamil Jaśkiewicz

Reputation: 33

Nodejs websocket communication with external system

I'm new to nodejs and I'm trying to solve communication issue with external system.

There is a gateway to external system which can handle websocket requests on port 5000. In the example below, when you request homepage, the nodejs opens websocket connection, then on websocket open event it sends request and waits for response which is used for the HTTP response.

Do you know how to open websocket to external system only once and handle requests based on request id?

var ws = require('ws');
var express = require('express');
var async = require('async');
var uuid = require('node-uuid');

app = express();

app.get('/', function (req, res) {
    var webSocket = new ws('ws://localhost:5000/');
    async.series([
        function (callback) {
            webSocket.on('open', function () {
                webSocket.send(JSON.stringify({query:'data query', requestid: uuid.v4()}));
                callback(null, 'data query');
            });            
        },
        function (callback) {
            webSocket.on('message', function (data, flags) {
                callback(null, data);
            })
        }
    ], function (err, results) {
        res.setHeader('content-type', 'text/javascript');
        res.send(results[1]);
        webSocket.terminate();
    });
});

var server = app.listen(3000, function () {
    var port = server.address().port
    console.log('Listening at %s', port)
});

Upvotes: 0

Views: 2641

Answers (1)

Kamil Jaśkiewicz
Kamil Jaśkiewicz

Reputation: 33

Thanks for the hints. I ended with the following solution which does what I expect:

var ws = require('ws');
var express = require('express');
var uuid = require('node-uuid');

var requests = {};

app = express();

var webSocket = new ws('ws://localhost:5000/');
webSocket.on('open', function () {
    console.log('Connected!');
});            

webSocket.on('message', function (data, flags) {
    var json = JSON.parse(data);
    console.log(json.requestId);
    var res = requests[json.requestId];
    res.setHeader('content-type', 'text/javascript');
    res.send(json.data);
    delete requests[json.requestId];
});


app.get('/', function (req, res) {
    var rid = uuid.v4();
    requests[rid] = res;
    webSocket.send(JSON.stringify({query:'data query', requestId: rid}));
});

var server = app.listen(3000, function () {
    var port = server.address().port
    console.log('Listening at %s', port)
});

Upvotes: 1

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