Rack is the interface behind Sinatra, and many other Ruby web frameworks. This section will cover middleware supported by Rack and Sinatra. Take a look at the Sinatra README and Sinatra Book for more on Rack middleware.
Did we miss something?
It's very possible we've left something out, thats why we need your help! This is a community driven project after all. Feel free to fork the project and send us a pull request to get your recipe or tutorial included in the book.
See the README for more details.