BANGALORE, INDIA: Cloud computing has become the talk of the town. Developers had been using Platform-as-a-Service or on-demand platforms to build applications that would run on the Cloud. This means, you can develop your applications and then host them on somebody else's infrastructure.

Google also has ventured into the cloud computing arena with their App Engine, which was first released as a Beta version in April 2008. Google App Engine not only leverages their massive infrastructure to the developers but also help them in reducing the time to write the code and deploying it on a Web server. Now, developers just have to build their apps and simply host them on App Engine. They do not have to bother about the complex setting up of the servers and their maintenance.

Google App Engine is still in its preview release, and costs nothing to get started. With a free account, one can get up to 500MB of persistent storage and enough CPU and bandwidth for about 5 million page views a month. The App Engine's virtualised computing environment caters to all the components of a modern web application: dynamic runtime, persistent storage, static file serving, emailing, monitoring and log analysis. Like any other cloud infrastructure, App Engine also provides scalability of the applications depending upon the traffic and data storage requirements.

App Engine SDK
The SDK provided by the Google to develop applications for the App Engine includes a Web server application that simulates the App Engine environment. Presently, App Engine supports only python programming language, but Google has said that later other language support will also be offered. In this article, we will see how to use App Engine SDK to build Web application and then host them online on Google's App Engine.

The App Engine SDK boasts of a strong API framework, which included Python scripting runtime, Google user accounts and mail service APIs, and datastore APIs that provides access to powerful persistence engine with querying and transaction support. The SDK also provides a server that emulates the Google App Engine platform. This helps developers to develop applications locally and check how it will perform on the Google's cloud upon deployment. Once you have created the application you can deploy it on Google's server using the command line.

Getting started
With this month's PCQ Professional DVD, we have distributed the Google App Engine version 1.1.5 and also the setup of Python 2.5.2 that is needed to run the App Engine platform. For this article, we will be using Windows as the operating platform, and so the installers provided in DVD are for Windows OS. The installers for Linux and Mac can be downloaded from the App Engine site. Since python is the pre-requisite for App Engine SDK, we need to install python version 2.5 first. Then you can install the App Engine SDK. Now you are ready to develop applications that will run on Google's cloud infrastructure.

 

To test that your setup is running; go to the command line and run the dev_appserver.py command. If an error message comes of invalid arguments, the App Engine server has been setup correctly.