Short example of how to declare services in AngularJS.

angularServices.js

//from most to least verbose, but it is all the same in the end. 

(function() {

    var module = angular.module("myApp.myModel", []);
    
    var MyModel = function MyModel() {
        this.asyncService = null;

        this.someApi = function() {
            return this.asyncService.getStuff(); //promise?
        }

    }

    var myModelProvider = Class.extend({
        model: new MyModel();
        $get: ['asyncService', function (asyncService) {
            model.asyncService = asyncService; //dependency injection
            return model; //resolved for the lifetime of app
        }]
    });

    modules.provider('myModel', myModelProvider);
}())

// or

(function() {

    var module = angular.module("myApp.myModel", []);
    
    var MyModel = function MyModel(asyncService) {
        this.asyncService = null;

        this.someApi = function() {
            return this.asyncService.getStuff(); //promise?
        }

    }

    module.factory('myModel', ['asyncService', function (asyncService) {
        //could do some stuff here
        return new MyModel(asyncService); 
    }]);

}())

// or

(function() {

    var module = angular.module("myApp.myModel", []);
    
    var MyModel = function MyModel(asyncService) {
        this.asyncService = null;

        this.someApi = function() {
            return this.asyncService.getStuff(); //promise?
        }

    }

    module.service('myModel', ['$asyncService', MyModel]); //most simple option
}())

@netpoetica -

$asyncService is another instance (of a Class, object, function) that was

1. registered with Angular (via .service() or .factory(), and then later...
2. instantiated by the Angular engine during the app bootstrapping processes

// register AsyncService to create instance of $asyncService
angular.module( "myApp.myModel", [ ])
          .service( "$asyncService", AsyncService)
          .service('myModel', MyModel);

This instance $asyncService is then injected as an parameter to the function MyModel( ) invocation; which creates an instance of myModel.

See how Angular allows you to create beans/services, define dependencies, and auto-injects those as needed?

@netpoetica -

angular.run() tells the NG engine to start

1. Processing the html to determine which Angular construction is needed
2. Instantiating all the required, registered services, values, and factories.

It uses ng-app, ng-controller etc in the HTML to determine what to load/instantiate at what time.

Thanks @ThomasBurleson. These were thrown together as a quick example for somebody and I never actually ran them (or even studied them more than a moment). Munged together from three code bases on my hard drive with names change to protect the innocent :>

@netpoetica Class is John Resig's simple class inheritance. http://ejohn.org/blog/simple-javascript-inheritance/

@joelhooks
Just working for you as a second pair of eyes ;-).

BTW, rumour/documentation implies that a factory creates a singleton. Since a service (which uses new) does not necessarily create a singleton, here is a way to easy force/manage singletons regardless of .factory() or .service() instantiations.

(function(angular) {
    "use strict";

    var _service    = null,
          _singleton = {
            asyncService : function() { return _service              },
            someApi      : function() { return _service.getStuff();  }
        };

        /**
         * MyModel constructor function
         */
        MyModel = function ($asyncService) {
            _service =  $asyncService || _service;
            return _singleton;
        };
    },


    // Redefine for minification...
    MyModel = [ '$asyncService', MyModel ];


    // Register `myModel` as an instance of the MyModel service or factory.
    angular.module( "myApp.myModel", [])
           .service('myModel', MyModel); 

}(angular));