Add option to configure Application channels

As discussed in #1321, configurable channels for applications will allow
multiple applications to exist on the same page without picking up each
other's events.

docs/marionette.application.md

@@ -18,11 +18,11 @@ var MyApp = new Backbone.Marionette.Application();
 * [Adding Initializers](#adding-initializers)
 * [Application Event](#application-event)
 * [Starting An Application](#starting-an-application)
-* [The Global Channel](#the-global-channel)
+* [The Application Channel](#the-application-channel)
   * [Event Aggregator](#event-aggregator)
   * [Request Response](#request-response)
   * [Commands](#commands)
-  * [Accessing the Global Channel](#accessing-the-global-channel)
+  * [Accessing the Application Channel](#accessing-the-application-channel)
 * [Regions And The Application Object](#regions-and-the-application-object)
   * [jQuery Selector](#jquery-selector)
   * [Custom Region Class](#custom-region-class)
@@ -114,11 +114,17 @@ var options = {
 MyApp.start(options);
 ```
 
-## The Global Channel
+## The Application Channel
 
 Marionette Applications come with a [messaging system](http://en.wikipedia.org/wiki/Message_passing) to facilitate communications within your app.
 
-The messaging system on the Application is the global channel from Backbone.Wreqr, which is actually comprised of three distinct systems.
+The messaging system on the Application is the radio channel from Backbone.Wreqr, which is actually comprised of three distinct systems.
+
+Marionette Applications default to the 'global' channel, but the channel can be configured.
+
+```js
+var MyApp = new Marionette.Application({ channelName: 'appChannel' });
+```
 
 This section will give a brief overview of the systems; for a more in-depth look you are encouraged to read
 the [`Backbone.Wreqr` documentation](https://github.com/marionettejs/backbone.wreqr).
@@ -184,14 +190,15 @@ MyApp.commands.execute("fetchData", true);
 MyApp.execute("fetchData", true);
 ```
 
-### Accessing the Global Channel
+### Accessing the Application Channel
 
-To access this global channel from other objects within your app you are encouraged to get a handle of the systems
+To access this application channel from other objects within your app you are encouraged to get a handle of the systems
 through the Wreqr API instead of the Application instance itself.
 
 ```js
 // Assuming that we're in some class within your app,
-// it is preferable to access the global channel like this:
+// and that we are using the default 'global' channel
+// it is preferable to access the channel like this:
 var globalCh = Backbone.Wreqr.radio.channel('global');
 globalCh.vent;
 

spec/javascripts/application.spec.js

@@ -78,4 +78,55 @@ describe('marionette application', function() {
       expect(this.startStub).to.have.been.calledOnce.and.calledWith(this.fooOptions);
     });
   });
+
+  describe('radio channels', function() {
+    describe('when channelName is specified', function() {
+      beforeEach(function() {
+        this.channelName = 'foo';
+        this.App = Marionette.Application.extend({ channelName: 'foo' });
+        this.app = new this.App();
+        this.channel = Backbone.Wreqr.radio.channel(this.channelName);
+      });
+
+      it('should create a Wreqr channel on this.channel', function() {
+        expect(this.app.channel).to.deep.equal(this.channel);
+      });
+
+      it('should set the app EventAggregator to the channel vent', function() {
+        expect(this.app.vent).to.deep.equal(this.channel.vent);
+      });
+
+      it('should set the app Commands to the channel commands', function() {
+        expect(this.app.commands).to.deep.equal(this.channel.commands);
+      });
+
+      it('should set the app RequestResponse to the channel reqres', function() {
+        expect(this.app.reqres).to.deep.equal(this.channel.reqres);
+      });
+    });
+
+    describe('when channelName is set as function', function() {
+      beforeEach(function() {
+        this.channelName = 'foo';
+        this.channelNameStub = this.sinon.stub().returns(this.channelName);
+        this.App = Marionette.Application.extend({ channelName: this.channelNameStub });
+        this.app = new this.App();
+      });
+
+      it('should set the app channelName to the result of channelName', function() {
+        expect(this.app.channelName).to.equal(this.channelName);
+      });
+    });
+
+    describe('when no channelName is specified', function() {
+      beforeEach(function() {
+        this.channelName = 'global';
+        this.app = new Marionette.Application();
+      });
+
+      it('should set the app channelName to "global"', function() {
+        expect(this.app.channelName).to.equal(this.channelName);
+      });
+    });
+  });
 });

src/marionette.application.js

@@ -7,13 +7,9 @@
 Marionette.Application = function(options) {
   this._initializeRegions(options);
   this._initCallbacks = new Marionette.Callbacks();
-  var globalCh = Backbone.Wreqr.radio.channel('global');
-  this.vent = globalCh.vent;
-  this.commands = globalCh.commands;
-  this.reqres = globalCh.reqres;
   this.submodules = {};
-
   _.extend(this, options);
+  this._initChannel();
 };
 
 _.extend(Marionette.Application.prototype, Backbone.Events, {
@@ -143,6 +139,15 @@ _.extend(Marionette.Application.prototype, Backbone.Events, {
     });
   },
 
+  // Internal method to setup the Wreqr.radio channel
+  _initChannel: function() {
+    this.channelName = _.result(this, 'channelName') || 'global';
+    this.channel = _.result(this, 'channel') || Backbone.Wreqr.radio.channel(this.channelName);
+    this.vent = _.result(this, 'vent') || this.channel.vent;
+    this.commands = _.result(this, 'commands') || this.channel.commands;
+    this.reqres = _.result(this, 'reqres') || this.channel.reqres;
+  },
+
   // import the `triggerMethod` to trigger events with corresponding
   // methods if the method exists
   triggerMethod: Marionette.triggerMethod