An application I write requires a certain type of concurrency access.

Multiple users are supposed to browse through a firebird database. In
the background, a sub-system is constantly feeding data into the
database. Users may from time to time call "refresh" to update their
view on the data.

Now, occasionally users would want to change data. This should
generally be permitted. Changes would be submitted to the db immediately.

The difficult part for me is now the requirement that users should
receive a message box if the record that they are editing has changed
when they submit their modifications. The user should then be free to
submit (i.e. overwrite) or cancel the update.

The sub-system in the background would never cancel its updates.

I have a vague feeling as if there should be a way to implement this
based on IBO transactions, but cannot figure out how.
My workaround solution would be to maintain a timestamp of the last
modification for each record and before posting updates check if the
timestamp has changed.
Any better idea?

Yuraukar.-