how do I start writing simple Json Rest enable server app in python

how do I start wri开发者_JAVA百科te simple (like Hello World) Json Rest enable server app in python, which I can run in Google App Engine.

Thanking you

I used this project for a GAE rest application :
http://code.google.com/p/appengine-rest-server/

The documentation is good and there are some examples to understand how it works. Very easy to use.