godfat / rack2

So this is an experiment and proof of concept to see if we could improve Rack without losing compatibility

Improving Rack

So this is an experiment and proof of concept to see if we could improve Rack without losing compatibility.

Core Goal

• Compatibility. But new features would only be available with new API.
• Compatibility is handled via Rack::Builder2
• Better encapsulation (Stop Rack::Request.new(env) all the way down)
• Easier streaming (mainly targeting HTTP/2)
• Remove Rack internal complexity (enough of respond_to? check and BodyProxy)

Current Implementation

• Old middleware and application should work as if
• New middleware could take the advantage of new SPEC (process_request(req, res) for now)
• If no old middleware were trying to walk through the response body (e.g. Rack::ContentLength), the call stack from application wouldn't see middleware around. (now it's iterating rather than stacking)
• Old middleware would suffer from some performance penalty due to the new compatibility layer. Move to the new API to restore performance.

Next Goal

• Access full response for new middleware (maybe via callback or buffer)
• Streaming for new middleware

See Also

• Rack 2.0, or Rack for the Future
• Yesod's Web Application Interface, source.

type Application = Request -> (Response -> IO ResponseReceived) ->
                   IO ResponseReceived

type Middleware = Application -> Application