What is OAuth authentication?

Question

I am developing an iGoogle Gadget. I have to access the spreadsheet data of logged in user. How do I implement an OAuth for it?

Answer 1

OAuth is just an API that Google gives out to developers to let them authenticate Google accounts in other manners other than just going on google.com - for example through a programmatic way.

Authentication is the basis of it, but through OAuth you're able to retrieve lots of information from a specific Google account (calendar info, contacts etc.)

To implement this you would need to read more on their website: https://developers.google.com/identity/protocols/OAuth2

Answer 2

You have to become an OAuth Consumer of the Google services - they are the OAuth provider in your case.

There are a lot of open source implementations of the protocol in various languages, but I would suggest to read through the RFC if you want to implement it - it's clearly written and not very long.

The official site has good reads and links too: http://oauth.net/

Basically it's a protocol that exchanges a little bit of data between you (your application aka the consumer), the provider and your user with internal HTTP requests between you and the provider (exchanging tokens) and some redirects through the user's browser between you and the provider again.

Also, you as a consumer will have to store some tokens and data regarding these interactions. It's not very complicated and in the same time is very interesting thing to implement. I learned things about security, request signing, some http details and headers. And if you already know these things, then you will do it a lot faster than I did :)