Porting a Grails application to GAE

Question

I currently have a Grails application I'm evaluating to port to Google App Engine and I'd like to know experiences regarding:

1. Acegi security: the application relies on this library to enforce the security (update: just learned that it's based on hibernate so can't be ported; any recommended replacements?).
2. Use of JPA or JDO instead of the hibernate plugin (I'll have to migrate the Domain classes); which one is better ?
3. I have a growing number of pre-generated pdf files I keep uploading; is there any foreseeable problem with this?

Thanks in advance.

Answer 1

I wrote a blog series about my experience with Grails on App Engine. It discusses most of your questions.

Answer 2

You may also be interested in Gaelyk (http://gaelyk.appspot.com/) Gaelyk is a lightweight wrapper which enables you to deploy applications written in Groovy to the App Engine.

Gaelyk offers a lot of the advantages of Grails including:

• standards for Views, Controllers
• flexible URL routing
• plugin system
• It has simple wrappers for the App Engine (including datastore access and coercion to POJO/POGOs, email, memcache, Jabber & more)

(although it doesn't include internationalisation, CRUD scaffolding or a HQL type query wrapper)

As it is more lightweight it doesn't have the performance issues on App Engine that Grails does and now that you can reserve instances http://code.google.com/appengine/docs/adminconsole/instances.html#Always_On it is possible to remove the startup time problems!

Answer 3

This isn't the answer you want, I'm sure, but I spent some time exploring Grails on GAE and finally came to the conclusion that it's not a good fit. By the time you give up (or work around) the native Domain capabilities, forego many of the plugins, and deal with the host of other minor incompatibilities, you've essentially wiped out most of the productivity advantage of Grails. I'd consider a standard J2EE, a compatible framework, or possibly a GWT based app for GAE. If you want to stick with Grails, I'd host it on AWS or a dedicated J2EE hosting provider.

That said, I hope the integration eventually works cleanly because GAE is a pretty cool engine/model.