Google App Engine proxy

What would be the simplest implementation of a proxy written for GAE, which relays every URL (including POST, and header data) to a remote HTTP host, and return with it's result (with special co开发者_开发技巧nsideration to error codes)? Please apply KISS principles!

I've found this proxy app from the Downy project works very well.

Downy, did not work with ajax/GAS. Use http://code.google.com/p/bs2grproxy/ BS2 GAE Reverse Proxy. I used it, with ajax (GAS), works fine.

How about [this one][1] ?

[1]: https://web.archive.org/web/20130102032034/http://google.com:80/codesearch/p#SKzQ5XqR4js/trunk/README&q=appengine http proxy