Omni.js is a framework designed to make building real-time apps with Backbone.js extremely easy. Simply define models, collections, and events on the server, and when a client connects it will automatically be given all of the information it has permission to see. Using Backbone.js from the client, you can then update the models and collections directly (i.e. Omni.collections.players.findWhere({name: "Jim"}).set("x", 10);, and all of the new information will be propagated by the server to any other clients who have permission to see these changes. You can define who has permission to read and write to models, and who has permission to add and remove models from collections.

Installation

npm install omni

Example Apps

• https://github.com/Mashlol/omni-chat-example - a very simple of example of how to use Omni.js effectively. - Demo: http://chat.kevinbedi.com
• https://github.com/Mashlol/omni-arena - a much more complex usage of Omni.js, building a realtime HTML5 arena game. - Demo: http://arena.kevinbedi.com
• https://github.com/jasmeeto/sketch-server - an online canvas-based sketch pad that syncs to all users in real-time. - Demo: http://sketch-server.herokuapp.com/

Usage

var Omni = require("omni");
var collection = new Omni.Collection([
    new Omni.Model({
        name: "foo",
        bar: "baz"
    })
]);
Omni.listen(3000, {
    collection: collection
});

The .listen(port, collections, events, options) method takes in a port, a list of instantiated collections, and a list of event objects. It returns a hash containing webSocket and express which contain the raw webSocket and express servers. The options parameter can take the following options:

• static - boolean, defaults to true. If false, Omni.js will not serve your /public folder automatically.
• development - boolean, defaults to false. If true, Omni.js will serve the client javascript unminified.

There is also a list of collections available on the Omni object, Omni.collections, which should work the same on both the client and the server. This way, within models and collections, you can use Omni.collections to keep code working on both the client and server. The Omni.collections object is only set after you have called Omni.listen().

Connection Properties

connection.sync() - This method can be called on any connection object that is passed between the permissions and event methods, and will run through each collection and each model and check if there are any changes in the permissions, and push the changes to the client. This is useful for instances where a change in one model might trigger some permission changes in another model or collection. For example, if a user has permission to read all other users in the same "room" as them, and you change that users room, you need to call this event to propagate all the new players they might be able to see, and remove all the old players they can no longer see. Note that this is a relatively intense method, use it wisely.

connection.socket - The raw socket.io socket object associated with this connection.

connection.connections - Returns an object containing all of the other connection objects, where the key is the socket ID. You can do things like:

for (var x in connection.connections) {
    connection.connections[x].socket.emit("myCustomEvent", {some: args});
}

Models

var Omni = require("omni");
 
var Player = Omni.Model.extend({
    defaults: {
        online: false,
        x: 0,
        y: 0,
        name: "name",
        password: "hash"
    },
 
    readPermission: function (connection, property) {
        if (property != undefined && property != "password" && this.get("online") || property == undefined) {
            return true;
        } else if (connection.player != null && connection.player == this) {
            return true;
        }
        return false;
    },
 
    writePermission: function (connection, property, value) {
        if  (connection.player != null && connection.player == this) {
            return true;
        }
        return false;
    }
});

A model is essentially the same as a model in Backbone, however a readPermission(connection, property) and writePermission(connection, property, value) method can be supplied to determine whether or not there is permission to read or write to this model.

The readPermission() method should return a value even if the property parameter is not passed in. The result of the method should be whether or not ANY attributes will be available. The method is called with only the connection parameter before checking each property individually, as if it returns false we won't need to iterate over all of the parameters. The connection parameter should be always be passed in, however.

All of the methods and properties you define in a model will also be propagated to the client. Prefix properties with an "_" if you wish to keep them on the server only. The readPermission and writePermission methods are kept on the server only. All of the backbone methods are also kept on the server, so overriding native Backbone methods is currently not possible on the client, but should still work on the server. If you wish to access or modify collections, use Omni.collections as this will work on both the client and the server.

Collections

var Omni = require("omni");
 
var Players = Omni.Collection.extend({
    model: Player,
    createPermission: function(connection) {
        return true;
    },
    destroyPermission: function(connection) {
        if (connection.player.get("admin")) {
            return true;
        }
        return false;
    }
});

A collection is essentially the same collection as Backbone, however a createPermission(connection) and destroyPermission(connection) method can be supplied to determine whether or not there is permission to add or remove models to/from this collection.

All of the methods and properties you define in a collection will also be propagated to the client. Prefix properties with an "_" if you wish to keep them on the server only. The createPermission and destroyPermission methods are kept on the server only. All of the backbone methods are also kept on the server, so overriding native Backbone methods is currently not possible on the client, but should still work on the server. If you wish to access or modify collections, use Omni.collections as this will work on both the client and the server.

Events

var loginEvent = {
    run: function (connection, collections, data) {
        if (connection.player) {
            return {error: "Already logged in."};
        }
        if (data.name && data.password) {
            var player = collections.players.findWhere({name: data.name, password: data.password});
            if (player) {
                connection.player = player;
                console.log(player.get("name") + " logged in.");
                return {success: "Logged in."};
            }
        }
        return {error: "Incorrect username or password."};
    }
}

Events allow for custom code to be run on the server when the client triggers the event.

Events are passed into the listen method of Omni as a hash, such as Omni.listen(1337, {collection: new Omni.Collection()}, {loginEvent: loginEvent});.

Predefined Events: connect, and disconnect. Any event passed in with these keys will be called automatically, and ignored in your Omni.trigger() calls on the client. The third (data) parameter will not be passed in for these events.

Client

Everything you should need should be readily available to access on the client. Right now, Omni.js automatically serves the public folder of your app at the port you specify. It also serves a client file (omni.js) at /omni.js. The client requires socket.io and Backbone, and Backbone requires Underscore, so your index.html head might look something like:

<head>
    <script src="/socket.io/socket.io.js"></script> 
    <script src="http://underscorejs.org/underscore-min.js"></script> 
    <script src="http://backbonejs.org/backbone-min.js"></script> 
    <script src="/omni.js"></script> 
 
    <script src="./your-custom-script.js"></script> 
</head>

The omni.js file automatically gives you the following:

Omni.collections (alias: window.Collections) - All the collections you defined on the server and passed into the listen method are automatically available in the global Collections object on the client, provided they have permission to see it. If I passed in a collection to the server with Omni.listen(1337, {messages: new Omni.Collection()});, I'd be able to access this collection on the client with Collections.messages. Then I can do things like Collections.messages.add({message: "Hello!"}) and the server will propagate this new message to all clients who have permission to see it.

Omni.trigger(eventName, args, callback) - This is how you trigger custom events. Once you trigger this custom event, the server will execute the code that you wrote inside the event hash with the name eventName. For example, with the loginEvent defined above, if the client sends Omni.trigger("loginEvent", {name: "foo", password: "bar"});, assuming a user with the name "foo" and password "bar" exists, it will set connection.player to that player model. This allows for the server to change the permissions of this user now, maybe to allow them to modify their own model more freely, or grant admin access, or other actions. The callback takes in a single parameter, which is the response hash.

Omni.ready(callback) - You can call Omni.ready() any number of times, providing callbacks. When Omni has downloaded the initial data from the server, these callbacks will be executed. If you call Omni.ready() after Omni has already initialized, your callback will be called immediately.

Omni.on(eventName, callback) - Add a callback for a certain client sided event. Currently the only event is sync, triggered when the server calls connection.sync() on this client's connection.

A note on persistance

Omni.js does nothing to interface with any databases, and so there is currently no persistance by default. You can, however, use Backbone's methods just like you would normally to persist objects. Unfortunately Backbone relies on jQuery or Zepto for this, using $.ajax to fetch information from the server. In order to get the Backbone methods that use $.ajax to work with Omni.js, you need to set Backbone.$ to an object with has an ajax method. E.g. require("backbone").$ = require("jquery"); Then you can use methods like Collection.fetch() or Model.save(), or any other persistance method just like normal.

Contributing

Feel free to contribute fixes, features or refactors. Just fork & submit a pull request. Please make sure the tests pass, and to update them if need be.

IRC

Hop on #omni.js on irc.freenode.net to discuss Omni.js, or to ask questions.

Testing

Run make test or npm test to run the tests.

Changelogs

v0.2.6

• Fix server listeners for model changes not triggering client updates for the client who triggered the server update

v0.2.5

• Fix removing models from collections

v0.2.4

• Quick bugfix

v0.2.3

• Fix client bug on sync which was adding listeners multiple times
• make sure change event is not triggered on the client when an objects oid and defaults are set by the server

v0.2.2

• Fix typo/bug causing sync() to be called every connect.

v0.2.1

• Add tests
• Add alias for recheckAllPermissions() to be sync() or resync()
• Add Omni.collections on the server.

v0.2.0

• Add the concept of OIDs, which are used internally by Omni to keep objects in sync with clients. This way, when clients add new models, they can still update their attributes without having to assign an ID. The server can also assign an ID after saving to a database, and the client will be updated based on the models OID.
• No longer reset collections when connection.recheckAllPermissions() is called. This way there is no need for updating references on the client every time the permissions are rechecked.

v0.1.1

• Add new option development which if true will serve the client javascript unminified.
• The url property for collections and models is now hidden from the client, defaults from models are now shown to the client.

v0.1.0

• Methods and properties from models and collections now propagate to the client. This does not include overridden Backbone methods. Any method prefixed with "_" is kept private to the server.
• Fixed serving of /public with no options param - Thanks to @evanbarter for this fix!

v0.0.11

• Remove leaked events on client
• Fix leak on server
• Add options parameter to Omni.listen(), currently with just the static option.

v0.0.10

• Lock versions for dependencies
• No longer use EJS to render the port into the client file, instead just use javascript to find the port.

v0.0.9

• The client.js file is now served minified.
• Added Omni.on(eventName, callback) on the client side. Currently the only event is recheckPermissions, triggered when the server calls connection.recheckAllPermissions() on this client's connection.
• Added connection.connections to the connection object so you can access other connections within events or permission methods.

v0.0.8

• Add connection.recheckAllPermissions() method to recheck permissions and propagate all data for that connection.
• Move connect event trigger to occur before Omni.js sends any data to the client. This way you can modify the connection object to change the outcome of the data that ends up being propagated.

License - MIT

Copyright © 2013 Kevin Bedi

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.