What is the preferred method of accessing the Gmail API across sessions without user input? E.g. user logs in once, some fairly-non-sensitive ID is stored on my server, and I use that ID along with my app's secret/key to access user's mailbox...
I noticed that OAuth 1.0 is now deprecated by google (I'm assuming that OAuth 1.0 enables the aforementioned login mechanism), so what should we use? Does OAuth 2.0 + IMAP work with Gmail?
I'm using a Rails 3.2.6 backend.
Without storing the user's password, the only way for full GMail access is using IMAP/SMTP with OAuth 1. With OAuth 2 you currently can only access the Atom Inbox Feed.
Though OAuth 1 was already marked deprecated by Google, it should be supported until April 2015.
UPDATE:
OAuth 2 authorization support for GMail IMAP/SMTP just recently arrived, so this is now the recommended way to go.