Google App Engine authorization with Google Apps Domain

I have successfully followed the examples to gain an AuthSub token to authorize my GAE application to have access to the user's Google Calendar.

I have added the domain parameter to the method gdata.auth.generate_auth_sub_url so that the application is authenticated against a Google Apps Domain user. The app is then installed in one of our test domains.

This is working fine, however, each user in the domain has to go through the process of authorizing the app to use the calendar. In other Marketplace Apps that I have tri开发者_JAVA技巧ed, this authorization is done once for the whole domain when the app is installed.

How is this achieved?

This page describes how Marketplace apps can access the gdata APIs on a user's behalf.