Posted by Chris Sells, Product Manager, Cloud Tools for Android Studio

Cloud Tools for Android Studio allows you to simultaneously build the service- and client-side of your mobile app. Earlier this month, we announced the release of Android Studio 1.0 that showed just how much raw functionality there is available for Android app developers. However, the client isn’t the whole picture, as most mobile apps also need one or more web services. It was for this reason that the Cloud Tools for Android Studio were created.

Cloud Tools put the power of Google App Engine in the same IDE alongside of your mobile client, giving you all the same Java language tools for both sides of your app, as well as making it far easier for you to keep them in sync as each of them changes.

Getting Started

To get started with Cloud Tools for Android Studio, add a New Module to your Android Studio project, choose Google Cloud Module and you’ll have three choices:

The Java Servlet Module gives you a plain servlet class for you to implement as you see fit. If you’d like help building your REST endpoints with declarative routing and HTTP verbs and automatic Java object serialization to and from JSON, then you’ll want the Java Endpoints Module. If you want the power of endpoints, along with the ability to send notifications from your server to your clients, then choose Backend with Google Cloud Messaging.

Once you’re done, you’ll have your service code right next to your client code:

Not only does this make it very convenient to build and test your entire end-to-end, but we also dropped a little extra something into your app’s build.gradle file:

The updated Gradle file will now create a library for use in your app’s client code that changes when your service API changes. This library lets you call into your service from your client and provides full code completion as you do:

Instead of writing the code to create HTTP requests by hand, you can make calls via the library in a typesafe manner and the marshalling from JSON to Java will be handled for you, just like on the server-side (but in reverse, of course).

Endpoints Error Detection

Meanwhile, back on the server-side, as you make changes to your endpoints, we’re watching to make sure that they’re in good working order even before you compile by checking the attributes as you type:

Here, Cloud Tools have found a duplicate name in the ApiMethod attribute, which is easy to do if you’re creating a new method from an existing method.

Creating an Endpoint from an Objectify Entity

If, as part of your endpoint implementation, you decide to take advantage of the popular Objectify library, you’ll find that Cloud Tools provides special support for you. When you right-click (or control-click on the Mac) on a file containing an Objectify entity class, you’ll get the Generate Cloud Endpoint from Java class option:

If you’re running this option on a Java class that isn’t built with Objectify, then you’re going to get an endpoint with empty methods for get and insert operations that you can implement as appropriate. However, if you do this with an Objectify entity, you’ll get a fully implemented endpoint:

Using your Cloud Endpoint

As an Android developer, you’re used to deploying your client first in the emulator and then into a local device. Likewise, with the service, you’ll want to test first to your local machine and then, when you’re ready, deploy into a Google App Engine project. You can run your service app locally by simply choosing it from the Configurations menu dropdown on the toolbar and pressing the Run button:

This will build and execute your service on http://localhost:8080/ (by default) so that you can test against it with your Android app running in the emulator. Once you’re ready to deploy to Google Cloud Platform, you can do so by selecting the Deploy Module to App Engine option from the Build menu, where you’ll be able to choose the source module you want to deploy, log into your Google account and pick the target project to which you’d like to deploy:

Cloud Tools beta required some extra copying and pasting to get the Google login to work, but all of that’s gone now in this release.

What’s Next?

We’re excited to get this release into your hands, so if you’ve haven’t downloaded it yet, then go download Android Studio 1.0 right now! To take advantage of Cloud Tools for Android Studio, you’ll want to sign up for a free Google Cloud Platform trial. Nothing is stopping you from building great Android apps from front to back. If you’ve got suggestions, drop us a line so that we can keep improving. We’re just getting started putting Google Cloud Platform tools in your hands. We can’t wait to see what you’ll build.

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Many Android developers like Snapchat or Pulse build and host their app backends on the Google Cloud Platform, and enjoy automatic management, with simple expansion to support millions of users.

To quickly add a Google Cloud Platform backend to your Android app, you can now use a number of built-in features in Android Studio 0.6.1+.

Google App Engine backend module templates

Google App Engine enables you to run your backend applications on Google's infrastructure, without ever requiring you to maintain any servers.

To simplify the process of adding an App Engine backend to your app, Android Studio now provides three App Engine backend module templates which you can add to your app. You can find them under "New → Module" menu:

1. App Engine Java Servlet Module provides a simple App Engine Java backend servlet with minimal boilerplate code,
2. App Engine Java Endpoints Module template leverages Google Cloud Endpoints for your backend, and includes automated object marshalling/unmarshalling, generation of strongly-typed Java client libraries and so on,
3. App Engine Backend with Google Cloud Messaging includes both Google Cloud Endpoints and Google Cloud Messaging integration, which enables additional features like push notifications.

When you choose one of these template types, a new Gradle module with your specified module/package name will be added to your project containing your new App Engine backend. All of the required dependencies/permissions will be automatically set up for you.

You can then run it locally (on http://localhost:8080) by selecting the run configuration with your backend's module name, as shown in the image below.

For more information about these backend templates, including their deployment live to App Engine and code examples which show how to connect your Android app to these backends, see their documentation on GitHub. (Also, the code for these templates lives in the same GitHub repository, so do not hesitate to submit a pull request if you have any suggestions!)

Built-in rich editing support for Google Cloud Endpoints

Once you have added the backend module to your Android application, you can use Google Cloud Endpoints to streamline the communication between your backend and your Android app. Cloud Endpoints automatically generate strongly-typed client libraries from simple Java server-side API annotations, automate Java object marshalling to and from JSON, provide built-in OAuth 2.0 support and so on.

As a concrete example, "App Engine Java Endpoints Module" contains a simple annotated Endpoints API at <backend-name>/src/main/java/<package-name>/MyEndpoint.java file (shown below):

import javax.inject.Named;

@Api(name = "myApi",
     version = "v1",
     namespace = @ApiNamespace(ownerDomain = "<package-name>",
                               ownerName = "<package-name>",
                               packagePath=""))
public class MyEndpoint {
    @ApiMethod(name = "sayHi")
    public MyBean sayHi(@Named("name") String name) {
        MyBean response = new MyBean();
        response.setData("Hi, " + name);
        return response;
    }
}

On deployment, this annotated Endpoints API definition class generates a RESTful API. You can explore this generated API (and even make calls to it) by navigating to Endpoints API explorer as shown in the image below:

To simplify calling this generated API from your Android app, Android Studio will automatically set up your project to automatically include all compile dependencies and permissions required to consume Cloud Endpoints, and will re-generate strongly-typed client libraries if your backend changes. This means that you can start calling the client libraries from your Android app immediately after defining the server-side Endpoints API:

As server-side Endpoints API definitions have to conform to a number of syntactic rules, Android Studio also includes a number of Endpoints-specific inspections and quick-fixes, which help you to avoid mistakes when writing Endpoints APIs.

For example, "@Named" annotation is required for all non-entity type parameters passed to server-side methods. If you forget to add this annotation when modifying sayHi method in MyEndpoint.java file, Android Studio will underline the problematic statement as-you-type:

Furthermore, to help you easily fix the problems with Cloud Endpoints, Android Studio will provide quick-fixes for the most common Cloud Endpoints development mistakes. To see these quick-fix suggestions, press Alt + Enter if you're running on Linux/Windows or ⌥ + Enter if you're running on Mac:

As expected, choosing the first quick-fix ("Add @Named") will automatically add "@Named" annotation to method's parameter, solving this problem in two key presses.

The underlying work-horses: Gradle, and Gradle plug-in for App Engine

Under the hood, Gradle is used to build both your app and your App Engine backend. In fact, when you add an App Engine backend to your Android app, an open-source App Engine plug-in for Gradle is automatically downloaded by Android Studio, and common App Engine tasks become available as Gradle targets. This allows you to use the same build system across your IDE, command-line or continuous integration environments.

For example, to deploy your backend to App Engine from Android Studio, you can launch the "appengineUpdate" task from the "Gradle tasks" tool window:

Similarly, if you want to integrate your backend's deployment into your command-line scripts, simply launch "./gradlew backend:appengineUpdate" command from your project's root directory.

Try out a codelab, or see these features live at Google I/O 2014!

If you want to give these features a spin in a more guided environment, try out our Cloud Endpoints codelab for Android. We will also be demonstrating some of these features live at Less Code, More Services, Better Android Apps session in Google I/O 2014 (as well as some of the new and even more exciting stuff), so don't forget to tune in!

We look forward to your questions or feedback, and learning about the amazing applications you have built using Android Studio and Google Cloud Platform. You can find us lurking on StackOverflow's App Engine and Cloud Endpoints forums!

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