I have a need to create a single sign on for my own apps that are on different domains. They happen to be on the same server now, but I don't want to rely on that.
Users would be signed in to App2, App3 and App4 the the traditional way. I want to place code on these apps that allows posting and receiving data to and from App1 as well as being able to move to App1 from one of the other apps.
My thought is to have a user_name, pass_word and site_id for each apps where perhaps site_id is "app2", "app3", "app4". On App2 where I would display a form to post or received data from App1, have a button to log into App1. That will cURL user info to to App1, if no username exists, it creates, otherwise displays appropriate data. Essentially creating a REST API with App1.
Looking for comments.