##Directory simple
The simplest app you can write using rack
- See Rack, a modular Ruby webserver interface at GitHub
- Rack: a Ruby Webserver Interface
- Rack interface specification
##Directory middleware
Simple example of using Rack middleware.
Middleware gives you a way to compose Rack applications together. See Exploring Rack by Arun Srinivasan
##Directory sinatra
Simple example of how to write a Rack middleware and use it from a Sinatra app.
See Rack Middleware at Sinatra site