Sinatra rides on Rack, a minimal standard interface for Ruby web frameworks. One of Rack’s most interesting capabilities for application developers is support for "middleware" -- components that sit between the server and your application monitoring and/or manipulating the HTTP request/response to provide various types of common functionality.
Sinatra makes building Rack middleware pipelines a cinch via a top-level
require 'sinatra' require 'my_custom_middleware' use Rack::Lint use MyCustomMiddleware get '/hello' do 'Hello World' end
Rack HTTP Basic Authentication
The semantics of "use" are identical to those defined for the Rack::Builder DSL (most frequently used from rackup files). For example, the use method accepts multiple/variable args as well as blocks:
use Rack::Auth::Basic do |username, password| username == 'admin' && password == 'secret' end
Rack is distributed with a variety of standard middleware for logging, debugging, URL routing, authentication, and session handling. Sinatra uses many of of these components automatically based on configuration so you typically don’t have to use them explicitly.