How to find out if a user is online in yii2?

Question

Yii

For example, by login or its id, or at least by a token, how can you find out?

Answer 1

Users are not online.
The user's connection to the website is not permanent, but discrete.
Therefore, the number of "users online" is always approximate, calculated from the time of the last request by the user of the site and the timeout - who has enough for what impudence.
The most stupid rascals take a session timeout - 24 minutes.