How to use autorun on server side?

I define a variable on the server side, and I want a function to autorun each time that variable changes.
due to Tracker.autorun() is not available on the server side, is there any alternative can be run on the server side?

It is available on the server, although in a rather limited fashion.

This library attempts to resolve that issue, and seems to do a pretty good job at it:

We extended it and now there is support also for reactive queries and reactive publish functions.