https://developers.gigya.com/010_Developer_Guide/10_UM360/030_Social_Login
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about:
Gigya is a social login / users management solution. This guide describes how to interact with social login platforms, and explains the workflow involved in Gigya's way of working
1. My Twhirl client asks last.fm for an OAuth token.
2. If last.fm considers me a friend of Kellan’s, it grants a token.
3. My Twhirl client sends an XMPP pubsub subscription request to last.fm, with appropriate OAuth bits