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The OAuth 2.0 specification is here: http://tools.ietf.org/html/draft-ietf-oauth-v2-21
Other helpful OAuth 1.0 and OAuth 2.0 information here: http://oauth.net/2/
For more information on the related (but still separate) click here: OAuth 2.0 Service Provider Implementation in Apache Shindig click here
Also being tracked at https://issues.apache.org/jira/browse/SHINDIG-1624
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