AngularJS: combine REST with Socket.IO

client-side-pseudo-code.js

'use strict';
 
angular.module('app.api.entities.task', ['app.api.rest.task'])
    .factory('Task', ['$rootScope', '$q', 'TaskApi', 'Socket', function($rootScope, $q, TaskApi, Socket) {
        // here we use a simple in memory cache in order to keep actual data
        // you can make it in any other way
        var cache = {};
 
        var initObject = function(data) {
            if (cache[data._id]) {
                // only extend existed object!!! in order to keep bindings
                angular.extend(cache[data._id], new Task(data));
            } else {
                cache[data._id] = new Task(data);
            }
            return cache[data._id];
        };
 
        var Task = function(data) {
            angular.extend(this, data);
        };
 
        Task.getAll = function(options) {
            var apiResult = TaskApi.getAll(options).then(function(tasks) {
                angular.copy({}, cache);
                _.map(tasks, function(task) { return initObject(task); });
                return cache;
            });
 
            if(_.isEmpty(cache)) {
                return apiResult;
            } else {
                return $q.when(cache);
            }
        };
        
        Task.getOne = function(id) {
            return TaskApi.getOne(id).then(function(task) {
                return initObject(task);
            });
        };
 
        Task.create = function(data) {
            return TaskApi.create(data).then(function(task) {
                return initObject(task);
            });
        };
        
        Task.prototype.remove = function() {
            var self = this;
            TaskApi.remove(self._id).then(function() {
                delete cache[self._id];
            });
        };
        
        // incluse SocketIO notifications service that will fire all the listeners on specified evnts
        // register listener for NewTask event
        Socket.on('NewTask', function(newTask) {
            // as we already have new task we just add it to cache with
            // initObject call
            initObject(newTask);
        });
        
        Socket.on('UpdateTask', function(updatedTask) {
            // as we already have new task we just add it to cache with
            // initObject call
            initObject(updatedTask);
        });
        
        Socket.on('DeleteTask', function(id) {
            // here we can find the task in the cache by its ID and remove it
            // this code is good for cache in object
            delete cache[id];
            // if we cache in array we should do something like
            var index = _.findIndex(cache, {_id: id});
            cache.splice(index, 1);
        });
 
        return Task;
    }]);

server-side-pseudo.js

var express = require("express");
var app = module.exports = express();
 
var Task = require('./task');
 
// some wrapper for SocketIO lib
var Pusher = require('pusher');
 
/**
 * Create new task from data in request body.
 */
app.post('/task', function(req, res, next) {
    Task.create(req.body)
      .then(function(task) {
        res.data = task;
        // emit SocketIO event with the _id of created resource:
        // req.body.to - is the _id of the user
        // task._id - is the _id of the newly created task
        Pusher.event('NewTask').send(req.body.to, task);
        return next();
      })
      .catch(next);
    );
});

app.put('/task', function(req, res, next) {
    Task.update(req.body)
      .then(function(task) {
        res.data = task;
        Pusher.event('UpdateTask').send(req.body.to, task);
        return next();
      })
      .catch(next);
    );
});