Rack is an interface to many Ruby web application. The last post showed how to use simple lambdas to define applications. Today, we explain how to use classes and what a Rack middleware is.
Rack Applications using Class Objects
Remember from the last post that any Ruby object can be used as a Rack application - as long as it answers to the call method. It’s perfectly valid to use a normal class object. Just take a look at the following code:
class HelloWorld
def call(env)
return [200, {"Content-Type" => "text/plain"}, body]
end
end
status = lambda do |env|
[200, {"Content-Type" => "text/plain"}, ["Running | #{Time.now}"]]
end
map '/' do
run status
end
map '/hello' do
run HelloWorld.new
end
Now, whenever we hit the '/hello' URL, the HelloWorld instance's call method is executed. Every Ruby class object can be used in this way inside a Rack application. Just think about all those projects you have made and how easy you can bring them to the web.
Read more at http://blog.sebastianguenther.org/2010/03/13/ruby-rack-using-objects-and-defining-middleware
