basic_middleware.rb

module Middleware
  class BasicMiddleware
    def initialize(app)
      @app = app
    end

    def call(env)
      # Before the app is called.
      status, headers, response = @app.call(env)
      # After the app is called.
      
      [status, headers, response] # It always needs to respond with [status, header, response].
    end
  end
end