@ngdoc overview
@name Cookbook: Deep Linking
@description

Deep linking allows you to encode the state of the application in the URL so that it can be
bookmarked and the application can be restored from the URL to the same state.

While <angular/> does not force you to deal with bookmarks in any particular way, it has services
which make the common case described here very easy to implement.

# Assumptions

Your application consists of a single HTML page which bootstraps the application. We will refer
to this page as the chrome.
Your application is divided into several screens (or views) which the user can visit. For example,
the home screen, settings screen, details screen, etc. For each of these screens, we would like to
assign a URL so that it can be bookmarked and later restored. Each of these screens will be
associated with a controller which define the screen's behavior. The most common case is that the
screen will be constructed from an HTML snippet, which we will refer to as the partial. Screens can
have multiple partials, but a single partial is the most common construct. This example makes the
partial boundary visible using a blue line.

You can make a routing table which shows which URL maps to which partial view template and which
controller.

# Example

In this example we have a simple app which consist of two screens:

* Welcome: url `welcome` Show the user contact information.
* Settings: url `settings` Show an edit screen for user contact information.


The two partials are defined in the following URLs:

* <a href="./examples/settings.html" ng:ext-link>./examples/settings.html</a>
* <a href="./examples/welcome.html" ng:ext-link>./examples/welcome.html</a>

<doc:example>
 <doc:source jsfiddle="false">
    <script>
     AppCntl.$inject = ['$route']
     function AppCntl($route) {
      // define routes
      $route.when("/welcome",  {template:'./examples/welcome.html',  controller:WelcomeCntl});
      $route.when("/settings", {template:'./examples/settings.html', controller:SettingsCntl});
      $route.parent(this);

      // initialize the model to something useful
      this.person = {
       name:'anonymous',
       contacts:[{type:'email', url:'anonymous@example.com'}]
      };
     }

     function WelcomeCntl($route){}
     WelcomeCntl.prototype = {
      greet: function() {
       alert("Hello " + this.person.name);
      }
     };

     SettingsCntl.$inject = ['$location'];
     function SettingsCntl($location){
      this.$location = $location;
      this.cancel();
     }
     SettingsCntl.prototype = {
      cancel: function() {
       this.form = angular.copy(this.person);
      },

      save: function() {
       angular.copy(this.form, this.person);
       this.$location.path('/welcome');
      }
     };
    </script>
    <div ng:controller="AppCntl">
      <h1>Your App Chrome</h1>
      [ <a href="welcome">Welcome</a> | <a href="settings">Settings</a> ]
      <hr/>
      <span style="background-color: blue; color: white; padding: 3px;">
        Partial: {{$route.current.template}}
      </span>
      <ng:view style="border: 1px solid blue; margin: 0; display:block; padding:1em;"></ng:view>
      <small>Your app footer </small>
    </div>
 </doc:source>
 <doc:scenario>
   it('should navigate to URL', function() {
    element('a:contains(Welcome)').click();
    expect(element('ng\\:view').text()).toMatch(/Hello anonymous/);
    element('a:contains(Settings)').click();
    input('form.name').enter('yourname');
    element(':button:contains(Save)').click();
    element('a:contains(Welcome)').click();
    expect(element('ng\\:view').text()).toMatch(/Hello yourname/);
   });
 </doc:scenario>
</doc:example>



# Things to notice

* Routes are defined in the `AppCntl` class. The initialization of the controller causes the
  initialization of the {@link api/angular.service.$route $route} service with the proper URL
routes.
* The  {@link api/angular.service.$route $route} service then watches the URL and instantiates the
  appropriate controller when the URL changes.
* The  {@link api/angular.widget.ng:view ng:view} widget loads the view when the URL changes. It
also
  sets the view scope to the newly instantiated controller.
* Changing the URL is sufficient to change the controller and view. It makes no difference whether
  the URL is changed programatically or by the user.
