extendsample.js

var baseService={
     $http: {},
     $q: {},
     rootUrl: 'http://localhost/api/',
     urlSuffix:'',
     get: function () {
         var defer = this.$q.defer();
         this.$http.get(this.rootUrl + this.urlSuffix)
             .success(function (response) {
                 defer.resolve(response.value);
             })
             .error(function (err) {
                 defer.reject(err);
             });
         return defer.promise;
     }
};

function ProductsService($http, $q) {
     this.$http = $http;
     this.$q = $q;
     this.urlSuffix = 'Products';
}
 
angular.extend(ProductsService.prototype, baseService);