A developer can create a new Rails app, build out the database schema and have an API that supports JSON and XML in just a few minutes. But then the work begins: authentication with oauth, throttling, rate limits, documentation,... The Apigee gem is a wrapper around the Apigee API management service, which makes API headaches go away.
Gemfile gem 'apigee', '~> 0.0.0.pre1'
install gem install apigee --pre