How can the messenger update the client's online status?

Question

Node.js

There is a task - to keep the status of the user always actual. Sockets are used on the server.
Current implementation: when a client authorizes, an event is called for all his contacts - login and logout, respectively
. Each time the client is opened, the entire list of contacts with the date of their last visit is naturally obtained

. What other options are there to solve this problem using api and / or sockets?