Ejemplo del uso de una arquitectura jerárquica de servicios

<!DOCTYPE html>
<html ng-app="plunker">

  <head>
    <meta charset="utf-8" />
    <title>AngularJS Plunker</title>
    <script>document.write('<base href="' + document.location + '" />');</script>
    <link rel="stylesheet" href="style.css" />
    <script data-require="angular.js@1.5.x" src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.5.11/angular.min.js" data-semver="1.5.11"></script>
    <script src="script.js"></script>
  </head>

  <body ng-controller="MainCtrl">
    <p>Hello {{name}}!</p>
  </body>

</html>

// Code goes here
const app = angular.module('plunker', []);

app.service('servicio1', function(){
  this.s1 = () => 'servicio uno'
});

app.service('servicio2', ['servicio1',function(servicio1){
  this.s2 = () => 'servicio dos ' + servicio1.s1();
}]);

app.controller('MainCtrl', 
[
  '$scope','servicio2',
   ($scope,servicio2) => $scope.name = 'World '+ servicio2.s2()
]);

/* Styles go here */