Question

I was looking at a schema and trying to figure out what this table could be used for:

CREATE TABLE "single_sign_ons" 
"token" VARCHAR(64) NOT NULL, 
"ip" VARCHAR(32) NOT NULL, 
"expired_at" DATETIME NOT NULL, 
"one_time" VARCHAR(64), 
"created_at" DATETIME, 
"updated_at" DATETIME, 
"user_id" INTEGER, 
PRIMARY KEY("token"));

What is “single sign on” and why did the author of this table include these columns for this purpose?

Answer 1

It’s a holder for a user’s sign-on session. I believe that the table would be used when a user has signed in to verify that their session is still active, and allow them to access diverse servers/sites without logging in a second time.

I’m assuming that at first login, the user’s session would be known to be new, so that the user would be queried for credentials. Then a row is entered in this table withe user’s id, ip address, creation date, and a token. This token would then be attached to the user’s session and used in subsequent logins.

Other processes would then recieve the token as part of the communication and check this table to be sure that the session is still valid. Each time the session is checked, the update field would be changed, so that the user is known to be active.

Still more logic would periodically check the table and expire any session rows that haven’t been updated recently enough. Whatever “enough” is for this system. Then subsquent access requests with the token will register the expiration, query for credentials and establish a new row with a new token.