In the past two weeks, Google has announced support for Java and Groovy on the Google App Engine. Various frameworks are supported, and the team at SpringSource is hard at work with a git repository fork of Grails for AppEngine.
What does that mean for us Java-heads?
- You will now be able to deploy a Java-based application to Google App Engine for free up to a certain number of page views per month (rumored to be somewhere near 5 million views per month)
- You can use some major Java frameworks, including Spring, some of Spring MVC (apparently they are sorting through the spring: tag lib), etc...
- You will have to code differently (just as the Python developers using the original App Engine did), because you're running on a non-relational data store (BigTable). However, you can use JDO and most of the features of JPA.
This is an interesting announcement. For quick applications (especially Grails-based) that you want to get out there for immediate feedback, you now have a place to drop them, free. Of course, coding for App Engine puts some pretty hard limitations on your architecture; you'd have to figure out whether or not you'd want to do something like that and whether it fits your ultimate goals. But for UI prototyping, quick burst apps like Facebook surveys, etc., it's an interesting alternative.
Even better, the Groovy team released Groovy 1.6.1, which is compatible with GAE. There are sample applications using Groovy Ant builder running around. Check here for a great article by Guillaume LaForge. Also see this, and this. A good message board exists on the Google Groups page.