AngularJS Pattern #1 - async service results

Spring Quizzo ETE sample code

Hi everyone. If you're looking for examples of potential ways to interact with a Spring app from AngularJS, take a look at the project I worked on with Pivotal's David Turanski for ETE, the Quizzo-ETE application.

It's at github.com/krimple/quizzo-ete. Highlights:

Now here's something I ended up using (but not as well as in here) for the quiz. It's a way to send a request to a Angular service asynchronously and receive a result via a message back to the component.

Asynchronous calls to services in Angular

In Angular, everything is asynchronous as much as possible to provide speed. A call to a $http service, which performs ajax methods, doesn't immediately return a value. If you decide to split up your Angular controllers and services, so you separate your UI from the calls to your backends, you'll quickly find that it becomes hard to get a response without some extra work.

One way to orchestrate calls is to use the Angular messaging framework, built into the $scope object. For example, in our controller we can execute a call to fetch games we're able to play right now, but we won't get the response right away. So, we can subscribe to a message, sent by our service, which will then come back to us with data. See this simple JSFiddle for an example:

The service uses a passed $scope variable. I've also injected a $rootScope into the service. Using that one would allow us to broadcast the message to any interested party.