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Java on Google App Engine - Time To Play In The Cloud

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It's been a long time coming, but today Google has announced that Java will be available on their App Engine. While the SDK is available for everyone to develop their applications locally, the initial sign up allowing people to upload their applications to the App Engine is limited to 10,000 users.

The Java environment provides a Java 6 JVM, a Java Servlets interface, and support for standard interfaces to the App Engine scalable datastore and services, such as JDO, JPA, JavaMail, and JCache. 

Google also released a plugin for Eclipse allowing you to create new web application projects, run them locally and deploy them to the App Engine. Check out this video to find out more about the Eclipse integration.

It's great to see that the App Engine is supporting Java, and it should really help with the adoption of Google's cloud service. Make sure that it meets your expectations by leaving feedback at the App Engine for Java group. There's a comprehensive list entitled "Will it play in App Engine" that tells you exactly what will and won't run. For example, EJB, JMS and web services aren't supported right now, but you can use Spring, Servlets and Scala to your hearts content.

As well as adding Java support, the team have been working on other features, as mentioned in their blog.

The team has also been working on many other improvements to App Engine, which we're really excited to launch to you as well:

  • Access to firewalled data: grant policy-controlled access to your data behind the firewall.
  • Cron support: schedule tasks like report generation or DB clean-up at an interval of your choosing.
  • Database import: move GBs of data easily into your App Engine app. Matching export capabilities are coming soon, hopefully within a month.


Reference: http://www.1160pm.net/2009/04/08/google-app-engine-for-java-and-google-plug-in-for-eclipse/


Thomas Mueller replied on Wed, 2009/04/08 - 8:56am

Request duration (essentially, 'JVM lifetime') is limited to 30 seconds. You can not spawn a thread or sub-process, open a TCP/IP socket or server socket (HTTP/HTTPS requests are OK), or write to the filesystem (you can only read; java.util.logging. is supported but not to file).

To persist data between requests you need to use the Google API, JPA, or JDO. There is also a 'Memcache' framework.

David Lee replied on Thu, 2009/04/09 - 2:32pm

Why didn't or couldn't Sun do this ?  Not for the cloud "stuff" by from the perspective of making java hosting an inexpensive, yet capable reality.

Jay Feghali replied on Thu, 2009/04/16 - 9:53pm

No project takes only 2 months to finish

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