How to track the open document which is opened by another person

The hyperlink can't go direct to the file: it has to go to a webpage (possibly with a identifying query string) which checks the DB and either serves the file or displays a message.

Your problem is "closing the file" - unless the remote client is forced to tell you when he closes it, there is no way to tell what he did with it: if he saved it and opened it in Adobe, viewed it via his browser, or just unplugged his PC and walked away. There is no signal that can tell you any of this!

You can add a timeout, similar to the session timeout which might try to prompt the user to indicate he isn't finished with it, but even then he may not get the message and continue reading.

I think you need to sit down and plan exactly what you are trying to do, as I suspect there is no good solution for the scenario you describe above.