How to dynamically work with word application in asp.net?

I am working on word report in ASP.NET application.
In my application i do permit the user to dynamically generate the
word document, so whatever changes user has made in word document.
i want back this changes in word document with that specifc user.
so how can i attach the event in word document?
what user close the opened word application then my code should execute
to read the word file .
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