Here are a few observations from my first 10 minutes of surfing around in the Google OpenSocial API docs.
The ATOM/REST APIs are collectively called the OpenSocial Data APIs.
The OpenSocial Data APIs are broken down into three groups:
- People & Friends Data API
- Activities Data API
- Persistence Data API
All the Data APIs require user login, and the current Google documentation only discusses use of Google user accounts. I’ve found no mention of whether user logins from other domains can be used here. Frankly, I doubt it.
Of the 3 data APIs listed above, only the People & Friends API is actually up and running. The Activities and Persistence APIs are documented but not yet available.
The Google user login mechanism (AuthSub) and general model of the People & Friends API appear at first blush to be conceptually identical to the Microsoft Windows Live Contacts API (my old stomping grounds), launched in May 2007. There’s going to be a massive patent battle in this area in a few years when the patents currently in process emerge from the other end of the USPTO pipeline.
One of the biggest differences between the OpenSocial People & Friends API and the Windows Live Contacts API is that OpenSocial does not support query filters. You can’t fetch just the friends that share an attribute (like, group or tag). Windows Live Contacts API has rich query capabilities right out of the gate. (You can play with Windows Live Contacts API queries here: http://www.randomthirdparty.com/)
I found no discussion in the Google docs of how third party social systems integrate into this OpenSocial API. Do they implement the same APIs on their own domains? Or are they merged together under the Google umbrella? Not clear yet. Still digging. Stay tuned.