What Is Google App Engine?

Google App Engine lets you run (host) your own Web applications on Google’s infrastructure. However, by no means is this a “rent a piece of a server” hosting service. With App Engine, your application is not hosted on a single server. There are no servers to maintain: You just upload your application, and it’s ready to serve your users. Just as servicing a Google search request may involve dozens, or even hundreds of Google servers, all totally hidden and satisfied in a fraction of a second, Google App Engine applications run the same way, on the same infrastructure. This is the unique aspect of Google’s approach. Yes, you cede some control to Google, but you are rewarded by being totally free of the infrastructure, capacity management, and load balancing tasks that enterprise typically have to manage, irrespective of whether they are self-hosting or hosting on someone else’s PaaS or IaaS.

You can serve your app from your own domain name (such as http://www.example.com/) using Google Apps or, you can serve your app using a free name on the appspot.com domain. You can choose to share your application with the world, or limit access to members of your organization.

Google App Engine supports apps written in several programming languages:

With App Engine’s Java runtime environment, you can build your app using standard Java technologies, including the JVM, Java servlets, and the Java programming language—or any other language using a JVM-based interpreter or compiler, such as JavaScript or Ruby. App Engine also features a dedicated Python runtime environment, which includes a fast Python interpreter and the Python standard library. The Java and Python runtime environments are built to ensure that your application runs quickly, securely, and without interference from other apps on the system.

Source: http://code.google.com/appengine/docs/whatisgoogleappengine.html

As with most cloud-hosting services, with App Engine, you only pay for what you use. Google levies no set-up costs and no recurring fees. Similar to Amazon’s AWS, resources such as storage and bandwidth are measured by the gigabyte.

App Engine costs nothing to get started. All applications can use up to 500 MB of storage and enough CPU and bandwidth to support an efficient app serving around 5 million page views a month, absolutely free. When you enable billing for your application, your free limits are raised, and you only pay for resources you use above the free levels.

Application developers have access to persistent storage technologies such as the Google File System (GFS) and Bigtable, a distributed storage system for unstructured data. The Java version supports asynchronous nonblocking queries using the Twig Object Datastore interface. This offers an alternative to using threads for parallel data processing.

“With Google App Engine, developers can write Web applications based on the same building blocks that Google uses,” Kevin Gibbs, Google’s technical lead for the project, wrote in The Official Google Blog. “Google App Engine packages those building blocks and provides access to scalable infrastructure that we hope will make it easier for developers to scale their applications automatically as they grow.”

Google App Engine has appeared at a time when an increasing number of tech companies are moving their operations to the cloud; it places Google squarely in competition with Amazon’s Elastic Cloud Computing (EC2) and Simple Storage Service (S3) offerings.

Google says its vision with Google App Engine is to offer developers a more holistic, end-to-end solution for building and scaling applications online. Its servers are configured to balance the load of traffic to developers’ applications, scaling to meet the demand of an influx of traffic. App Engine also includes APIs for user authentication to allow developers to sign on for services, and for e-mail, to manage communications.

InternetNews.com reported,

Through its initial preview, Google’s App Engine will be available free to the first 10,000 developers who sign up, with plans to expand that number in the future.
During that period, users will be limited to 500MB of storage, 10GB of daily bandwidth and 5 million daily page views, the company said. Developers will be able to register up to three applications.

Source of Information : Implementing and Developing Cloud Computing Applications 2011

What Is Google App Engine?