Proxy server that's supposed to be accelerate remote calls in Shopify.
Inspired by Ilya Grigorik's inspired piece of work on EM based proxies:
Shopify forwards web requests to many remote locations for API apps. Api apps roughly work like facebook applications in the sense that the web requests arrives at Shopify's door but then needs to be forwarded to an arbitrary proxy endpoint.
If we would do these remote calls within the rails code we would quickly run out of mongrels even if one of the backend services would be slow.
This proxy server will check memcached for the endpoint URL and - if present - perform the HTTP request. After the http request is successfully completed it will stick the result into memcached and set two headers X-Proxy-Status and X-Proxy-Content before sending the request Shopify for further processing (liquid).
This code is protected by the fact that it solves a proprietary problem. I hope it can serve as an example for people solving similar issues and I hope it will further the excellent discussion that Ilya kicked off.