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Yet Another Example of WebSockets, Socket.io and AngularJs Working With a Silex Backend

· Java Zone

Check out this 8-step guide to see how you can increase your productivity by skipping slow application redeploys and by implementing application profiling, as you code! Brought to you in partnership with ZeroTurnaround.

Remember my last post about WebSockets and AngularJs? Today we’re going to play with something similar. I want to create a key-value interface to play with websockets. Let me explain it a little bit.

First we’re going to see the backend. One Silex application with two routes: a get one and a post one:

include __DIR__ . '/../../vendor/autoload.php';
include __DIR__ . '/SqlLiteStorage.php';
use Silex\Application;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Silex\Provider\DoctrineServiceProvider;
$app = new Application([
    'debug'      => true,
    'ioServer'   => 'http://localhost:3000',
    'httpServer' => 'http://localhost:3001',
$app->after(function (Request $request, Response $response) {
    $response->headers->set('Access-Control-Allow-Origin', '*');
$app->register(new G\Io\EmitterServiceProvider($app['httpServer']));
$app->register(new DoctrineServiceProvider(), [
    'db.options' => [
        'driver' => 'pdo_sqlite',
        'path'   => __DIR__ . '/../../db/app.db.sqlite',
$app->register(new G\Io\Storage\Provider(new SqlLiteStorage($app['db'])));
$app->get('conf', function (Application $app, Request $request) {
    $chanel = $request->get('token');
    return $app->json([
        'ioServer' => $app['ioServer'],
        'chanel'   => $chanel
$app->get('/{key}', function (Application $app, $key) {
    return $app->json($app['gdb.get']($key));
$app->post('/{key}', function (Application $app, Request $request, $key) {
    $content = json_decode($request->getContent(), true);
    $chanel = $content['token'];
    $app->json($app['gdb.post']($key, $content['value']));
    $app['io.emit']($chanel, [
        'key'   => $key,
        'value' => $content['value']
    return $app->json(true);

As we can see we register one service provider:

$app->register(new G\Io\Storage\Provider(new SqlLiteStorage($app['db'])));

This provider needs an instance of StorageIface

namespace G\Io\Storage;
interface StorageIface
    public function get($key);
    public function post($key, $value);

Our implementation uses SqlLite, but it’s pretty straightforward to change to another Database Storage or even a NoSql Database.

use Doctrine\DBAL\Connection;
use G\Io\Storage\StorageIface;
class SqlLiteStorage implements StorageIface
    private $db;
    public function __construct(Connection $db)
        $this->db = $db;
    public function get($key)
        $statement = $this->db->executeQuery('select value from storage where key = :KEY', ['KEY' => $key]);
        $data      = $statement->fetchAll();
        return isset($data[0]['value']) ? $data[0]['value'] : null;
    public function post($key, $value)
        $statement = $this->db->executeQuery('select value from storage where key = :KEY', ['KEY' =>; $key]);
        $data      = $statement->fetchAll();
        if (count($data) > 0) {
            $this->db->update('storage', ['value' => $value], ['key' => $key]);
        } else {
            $this->db->insert('storage', ['key' => $key, 'value' => $value]);
        return $value;

We also register another Service provider:

$app->register(new G\Io\EmitterServiceProvider($app['httpServer']));

This provider’s responsibility is to notify to the websocket’s server when anything changes within the storage:

namespace G\Io;
use Pimple\Container;
use Pimple\ServiceProviderInterface;
class EmitterServiceProvider implements ServiceProviderInterface
    private $server;
    public function __construct($url)
        $this->server = $url;
    public function register(Container $app)
        $app['io.emit'] = $app->protect(function ($chanel, $params) use ($app) {
            $s = curl_init();
            curl_setopt($s, CURLOPT_URL, '{$this->server}/emit/?' . http_build_query($params) . '&_chanel=' . $chanel);
            curl_setopt($s, CURLOPT_RETURNTRANSFER, true);
            $content = curl_exec($s);
            $status  = curl_getinfo($s, CURLINFO_HTTP_CODE);
            if ($status != 200) throw new \Exception();
            return $content;

The Websocket server is a simple socket.io server as well as a Express server to handle the backend’s triggers.

    express = require('express'),
    expressApp = express(),
    server = require('http').Server(expressApp),
    io = require('socket.io')(server, {origins: 'localhost:*'})
expressApp.get('/emit', function (req, res) {
    io.sockets.emit(req.query._chanel, req.query);

Our client application is an AngularJs application:

<!doctype html>
<html ng-app="app">
    <script src="//localhost:3000/socket.io/socket.io.js"></script>
    <script src="assets/angularjs/angular.js"></script>
    <script src="js/app.js"></script>
    <script src="js/gdb.js"></script>
<div ng-controller="MainController">
    <input type="text" ng-model="key">
    <button ng-click="change()">change</button>
angular.module('app', ['Gdb'])
    .run(function (Gdb) {
            server: 'http://localhost:8080/gdb',
            token: '4b96716bcb3d42fc01ff421ea2cfd757'
    .controller('MainController', function ($scope, Gdb) {
        $scope.change = function () {
            Gdb.set('key', $scope.key).then(function() {
                console.log("Value set");
        Gdb.get('key').then(function (data) {
            $scope.key = data;
        Gdb.watch('key', function (value) {
            console.log("Value updated");
            $scope.key = value;

As we can see the AngularJs application uses one small library called Gdb to handle the communications with the backend and WebSockets:

angular.module('Gdb', [])
    .factory('Gdb', function ($http, $q, $rootScope) {
        var socket,
            watches = {};
        var Gdb = {
            init: function (conf) {
                gdbServer = conf.server;
                token = conf.token;
                $http.get(gdbServer + '/conf', {params: {token: token}}).success(function (data) {
                    socket = io.connect(data.ioServer);
                    socket.on(data.chanel, function (data) {
                        watches.hasOwnProperty(data.key) ? watches[data.key](data.value) : null;
            set: function (key, value) {
                var deferred = $q.defer();
                $http.post(gdbServer + '/' + key, {value: value, token: token}).success(function (data) {
                return deferred.promise;
            get: function (key) {
                var deferred = $q.defer();
                $http.get(gdbServer + '/' + key, {params: {token: token}}).success(function (data) {
                return deferred.promise;
            watch: function (key, closure) {
                watches[key] = closure;
        return Gdb;

And that’s all. You can see the whole project at github.

The Java Zone is brought to you in partnership with ZeroTurnaround. Check out this 8-step guide to see how you can increase your productivity by skipping slow application redeploys and by implementing application profiling, as you code!


Published at DZone with permission of Gonzalo Ayuso, DZone MVB. See the original article here.

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