Google App Engine

Google App Engine (GAE) lets you run web applications on Google infrastructure.  The good thing in this technology is that there's no need for you to maintain the server.  You can also use this technology as backend to your android applications (it means that this provides the data exchange between your android application, application server, and GCM).  You can run Java, Go, and Python environments for your web application environment.  This article will tackle Java and Android stuffs.  More of this stuff can be found here.

To send/receive JSON data for an Android application.
In this article, I use Eclipse on Ubuntu for the development.

Installation

Download the Google App Engine SDK for Java here.

In Eclipse, go to Help > Install New Software > Work With textbox, get the Eclipse update site url here.

Right after the installation, Google plugin is added in the Eclipse toolbar.

Now you can

Creating and Running a Web Application

To create a sample web application, click on the Google plugin then select 'New Web Application Project' and click 'Finish'. A sample Hello World code is provided in your new web application project.  To Run, hit on Run button, Run As > Web Application.  Check and see your browser.  Your web application project is hosted locally.  The url is http://localhost:8888.

Then deploy this project in GAE.  To deploy, click the Google plugin and click Deploy To App Engine > App Engine Project Settings > enter your ProjectId in the Application ID textbox > hit OK > Deploy

Once deployment is successful, you can see something like this image below.