Hi Tesfaye,
This is a question you should ask to the maintainers of the
Open Data Kit (I just looked this up now). This forum is meant for discussion of the underlying web-application platform that ODK or its website might use, but even that much isn't clear from their website, so I'm not even sure if ODK bears zero relation to
App Engine and the forum you've posted to.
I think you stand a much better chance of getting your question answered with them, although feel free to reply here if you think there's a relation to App Engine worth discussing.
SIncerely,
Nick