1) ASP.NET MVC3 project, based on N2 CMS, database - Microsoft SQL Server
2) Users may logon using their Twitter, Facebook, Google accounts, or by creating accounts directly with our site
What we want to achieve:
1) We want Couponics to use the same accounts as our site. We can achieve it if we create Couponics account in the same time as we create our site's account, so we need a method that we can use to create and update a User Account in couponics from ASP.NET. Ideally it can be a stored procedure in Couponics MySQL Database
2) We want user to logon only on our site and then use the same logon with couponics. So we need a way to authenticate user with couponics, preferrably without using password, since Twitter/Facebook/Google accounts do not share password with our site. Technically I see it the following way - we need a custom page on Couponics side which we can call in iframe passing it a username and some logon token. This page will call back the site to validate token and then will authenticate user in couponics and issue corresponding cookie. Then user's browser is redirected to couponics and he is already logged on.