Google App Engine proxy to one host

Is there any open source app I can upload to Google App Engine, that proxies all re开发者_JAVA技巧quests (including POST and cookies) to a hostname that I choose?

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Here you can find a guide and the source code to set up a GAE proxy based on Mirrorr, an open-source web caching project by Brett Slatkin.

Here is a list of other proxy projects.