Roo's bean Validation (JSR 303) support, would it work on GAE?
As far as I know, Roo uses Hibernate validator and Hibernate does not work on GAE.
Or it is possible to use just hibernate validation without using actual hibernate !
Ooops, I stand corrected. You'll need to use org.datanucleus.store.appengine.jpa.DatastorePersi stenceProvider as your JPA provider. That's what the sample project in ROO-146 used.
We are addressing cloud interop in the next major version of Roo, so expect to see far better integration coming shortly.
In theory you should be able to use Hibernate Validator without Hibernate. For example Spring Framework 3 uses JSR 303 in its web tier for validation, and Roo uses this feature to validate presented form backing objects. As such my advice is to simply give it a try. Roo automatically adds Hibernate Validator to your project when you insert the field field that uses JSR 303 (Bean Validation) annotations.