Solved the Single Sign-On (SSO) problem [Figure]

A few days ago, the website was about to go online, but another serious problem was not solved, that is, single point of login.
The website has three second-level domain names:
Www.xxxx.com// Front-end system
Member.xxxx.com // Member System
Ren.xxxx.com // ** System

Now, after you log on to any domain, you do not need to log on to the other two domains. You have read many related articles on the Internet, most of them are talking about using CAS from Yale University to solve the SSO problem. So I read the CAS instructions and introduction. I have called it myself, and I feel it is still okay, but I personally think there is a drawback, that is, it must use HTTPS protocol, so that when users log on, it is troublesome to select any certificate. users do not want to perform so many operations. The simpler the better, the better. So they want to abandon CAs to solve the current SSO problem, I don't know which one to use at half past one, so I will continue to read the introduction of CAS. When I see the implementation principle of CAS, the more I see it, the more I read it three times in a row, I finally understood and understood it. I thought, and thought, it seemed that I could implement it myself. So I started to write a class of "User Registration Center" first, after logging on to all users, you must register here, and then write a filter to verify whether the user has logged on. in XML, prepare and run ............... test ........ cool stayed, succeeded, succeeded, and suddenly felt that the world is really beautiful, that joy is hard to describe ....
The following is my SSO implementation method. I can understand it, haha ....