An edge server is a proxy.

The origin server is the one that tells the edge server exactly what content should be returned for a particular request.

The origin server may be running Java, Ruby, Node.js, or any other type of web server and, therefore, can do anything it wants.

The edge server does nothing but make requests and serve content.

所以像 YUI combo 或 minify 機制是做在 Origin 端，而不是 Edge 端