The Rails Metal in Ruby on Rails 3

I am using Ruby on Rails 3 and I would like to implement some Rack middleware.

I know (but maybe I am wrong!) that, before of version 3, there was the Rails Metal "system" to handle those. But now?!

Where in my Rails application I have to locate files to use for middleware purposes (before of version 3, if I am not wrong, the folder was named 'metal')? then, ho开发者_如何学Pythonw I must state them in the application.rb file?

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Check out the Rails on Rack page on Rails Guides.

Your own middlewares can be stored in lib and can be required at the top of application.rb.

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Checkout the following blog post, that may answer your question:

http://tektastic.com/2010/07/rails3-rack-and-where-did-my-metal-go.html

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Check out this http://www.engineyard.com/blog/2010/rails-and-merb-merge-plugin-api-part-3-of-6/ for how to create a "Metal" controller

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http://www.ruby-on-rails-outsourcing.com/articles/2010/05/28/how-to-create-your-own-rack-middleware-class-in-ruby-on-rails/ may be helpful for you.

It basically suggests to put your class in /lib/class_name.rb and then instruct it to be used like

 Rails::Initializer.run do |config|
   config.middleware.use "ClassName"
 ...

I believe you are right there is no more "metal" option in rails 3 http://tektastic.com/2010/07/rails3-rack-and-where-did-my-metal-go.html you have to use a rack middleware instead. I'm unsure if this causes a performance hit or not.