Google App Engine

An Early Look at Java™ Language Support
App Engine recently unveiled its second language: Java. This release includes an early look at our Java runtime, integration with Google Web Toolkit, and a Google Plugin for Eclipse, giving you an end-to-end Java solution for AJAX web applications. Our support for the Java language is still under development and we're eager to get your help and input. The Java runtime is now available for anyone to use, so please give it a try and send us your feedback.

• Get the full scoop in our blog post.
• Click over to YouTube to watch our Campfire One announcements.
• See our docs for other new features like cron support, database import, and access to firewalled data.

Getting started
Here’s how to get rolling:

1. Install the gems
   $ sudo gem install google-appengine

2. Assign an app identifier

   Simply create an application at appspot.com,
   we'll refer to that as my-app in this document.

3. Generate your rails app

   $ rails my-app; cd my-app;

4. Generate a rackup file

   In the same folder, save this as config.ru.

   require 'appengine-rack'
   AppEngine::Rack.configure_app(
   :application => 'my-app',
   :version => 1 )
   
   ENV['RAILS_ENV'] = AppEngine::Rack.environment
   require 'config/environment'
   run ActionController::Dispatcher.new
   

5. Check gem sources for datamapper

   $ gem sources

   Only when missing, add it like this...
   $ sudo gem source -a http://gems.datamapper.org

6. Install gems into your app

   $ appcfg.rb gem install rails dm-appengine

7. Modify the Rails Initializer

   Add the following to your config/environment.rb.

   # Set DataMapper to use dm-appengine adapter
   require 'dm-core'
   DataMapper.setup(:default, "appengine://auto")
   
   # Set Logger from appengine-apis, all environments
   require 'appengine-apis/logger'
   config.logger = AppEngine::Logger.new
   
   # Skip frameworks you're not going to use.
   config.frameworks -= [ :active_record ]
   

8. Run your app locally

   $ dev_appserver.rb .

9. Open up the console

   $ appcfg.rb run -S irb
   > require 'config/environment'

10. Deploy to App Engine

    $ appcfg.rb update .

http://code.google.com/appengine/
http://rails-primer.appspot.com/