Calling Google Play Purchase Status API from App Engine

[Pertti Kellomäki]

I need to verify Android inapp purchases (subscriptions to a web site)
in my App Engine based server. It looks easy enough to do with the
Purchase Status API [1], but I'm not sure I understand the
authentication required.

According to the documentation, calls to the API are authenticated
with OAuth2, and from what I have gathered it uses the web server
flow. If really necessary I can go through the oauth dance, get a
refresh token, and embed it in my application. Is this really the
only/correct way to do it?

[1] <http://developer.android.com/google/play/billing/gp-purchase-status-api.html>
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Pertti

[Pertti Kellomäki]

For the record, I ended up following the directions in
<https://milancermak.wordpress.com/2012/08/24/server-side-verification-of-google-play-subsc/>
to get a refresh token. The procedure is somewhat clumsy but not too
painful. In the server, I create an
oauth2client.client.OAuth2Credentials instance with a fake access
token and the real refresh token, and use .refresh() to force fetching
a new access token.

Getting the purchase status from Google Play is a simple http GET
which I do with urlfetch.fetch().

Pertti