Building local proxy that pausing requests

It’s a general question about ruby development.

I am wondering if it’s possible to develop a local proxy that pauses
requests sent from local clients until I say yes.

For example,

  1. an user tries to access http://www.google.com from browser.
  2. a locally activated proxy server captures the request and stops
    there.
  3. If I say yes, the sent request will be forwarded to www.google.com
    server
    if I say no, the sent requests are to be dropped, www.google.com
    server received no request.

I know that using WEBrick::HTTPProxyServer will help create a simple
proxy.
My question is how to develop a proxy that pools incoming requests until
forwarded at will, if possible.

I appreciate you help.