Open Source Document Management System | OpenKM

we have a requirement where we need to send email users when somebody writes a "note" and selects to notify users/roles.
any guidance on how to add this functionality.
specifically which API to call to send emails once we have captured user input of notification message, users/roles.
I am finding it difficult to understand the flow from the document upload functionality.
I am using community edition,

Should be extended the source code for watching the add notes events what now are not listening. I can give you some clues about how doing it ( if you are a JAVA skilled, otherwise forget doing ).