[eluser]rideearthtom[/eluser]
Hello,
I've run into a concept with which I have no experience and was hoping for some advice.
I've been contracted to work on a project which spans several distinct web apps with their own domains and hosting solutions. I'll be using CI. The general model is that there is a central app which acts as a payment-processing and user-authentication back-end to each of the child apps.
This central app provides administrative functionality to the client who operates the network of sites - they can perform various actions on the users and transaction-related objects. There is no public interface to this app, it's just for admin use and providing interface with the child sites.
Each child site offers a unique product/solution, and these sites won't have anything in common except for using the central app's authentication-related functionality and payment-processing functionality. On each of the child sites, the user should be able to register/login, 'buy' the product, and access product material through a user-area. The user will also need to submit profile information, and this will be different for each child site. The profile and purchase details should be stored in the central app, and at all times, the central app should remain transparent, so as far as the user is concerned they've visited the child site, signed up, paid and accessed the online materials without interacting directly with any other site.
I've already built the central app as a standalone site, with registration/login (using Redux Auth), products, payment processing, etc, and the data model is complete. I've also built one of the child sites, which simply redirects to the central app when it comes to payment. However, the client has changed his requirements and now wants the payment/auth process to be transparent so that the user never appears to leave the client site. He wants this functionality to be reusable across any number of child sites, each being related to a single product defined within the central app.
I have plenty of experience developing web apps, but no experience with the concept of cross-site authentication providers and cross-site back-end interaction. I'm having a little difficulty figuring out how to get started, where to store what, how to ensure data integrity, how to abstract varying profile information per-product/child site without creating redundancy or hard-coding it, how to provide cross-site auth and other functionality, etc.
That's the simple version, anyway. Hope someone out there can figure out what I'm talking about and offer some ideas!
EDIT: I'm not asking for a system where the user logs in and can access several domains simultaneously with that authed session - just for a single login/registration repository and functionality to be used on several other domains to register and login to each.
