I am new to this but I will try my best to explain what I am trying to do.
I have a catalog of products and various private information that my users want to be able to access via their website.
For example:
User-a has an e-commerce site and they want to sell my merchandise. They will be able to access a certain products details via a web service. They will also be able to see the negotiated rate that I've given them along with some other private details.
How should the API handle authenticating the request that comes from User-a's website?
I've been reading all day about different authentication methods but they all seem to revolve around the idea of a third party accessing specific user information. An example is if you let http://randomtwitterapp.com access your twitter profile. In that case, the third party site must manage multiple different users and auth tokens. In our case, my users website is interacting on behalf of the user. I hope this makes sense.