CloudSpring: Writing apps in your favorite language on the web is fun and rewarding for developers — and can be a good value proposition for small businesses and start ups. This is easily possible with Google App Engine (GAE), with Java as the language of development. It’s very important to know the landscape within which you can build your application using emerging GAE, and to understand the limitations of an evolving product. Sandboxed Runtime Environment for Java Applications in Google run on Java 6 JVM, and the SDK supports Java 5 or later.
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Understanding Google App Engine (GAE) Java API Part 1: Landscape Overview