Question

How can I prevent multiple users from being logged in at the same time with a single user ID?

I searched the internet and found some ways, but they do not work in these situations:

1. If JavaScript in the browser is turned off.
2. If the user does not click "logout" and instead directly closes the browser.

Suggestions would be appreciated. Thanks.

Answer 1

There could be several possibilities. A quick response is:

1. Maintain a flag in database; upon every login/out update the flag. For instance, upon every authentication request you can reject the login request if the flag is already true.

2. Alternatively, you can maintain a list of users in the Application object and use .Contains to see if it already exists.

–EDIT–

Lets try the database flag option; and assume that you have a method called StillLoggedIn(User) that updates the date/time and flag.

So, when user logs in:

1. The app is going to authenticate the user and set flag=1, and mark a date/time stamp.

2. For subsequent requests, the app would call StillLoggedIn(User);

3. Prepare a windows service that would browse the database from time to time(lets say after 5 minutes if you have 10000 users). The service would compare the database date/time with the current date/time and mark the flag as 0 if the currentTime minus lastUsedTime is greater than, lets say, 5 minutes.

It could be anything besides a database and windows service.