Concurrency (recap And Idea).....

With respect to my (now not so recent) thread on Concurrency, I would like
to run my idea past you gurus to see if its a runner. First, a brief recap:

I have a single user system (one user, one copy of the software, one copy of
MSDE, one machine) that I wish to convert into a multi-user/single database
networked system. The problem I had was that a lot of information is
fetched from the database and cached in the client program (the program
implements a tree structure, similar to a file system, and each of the nodes
in the system has properties). The concurrency issue revolved around having
multiple users updating these properties and possibly able to modify the
tree structure and there being no way to notify the other clients that they
need to refresh their data structures. Consider the system to be similar to
VSS to look at (and in VSS, people can make modifications to the tree
structure also!).

Ok, one of the suggestions was time stamping each record. So, when one user
modifies the record, a second user can detect whether their timestamp is
different and thus whether or not their update is invalid (and also whether
or not the client program needs to refresh the properties of the given
node). How about instead of a timestamp I simply use a reference counter.
ie. an integer that increments every time the record is modified (same
principle). I don't need to know when it was changed, just that the two
reference counters are different between when I fetched and when I am
updating the record.

Secondly, I think I have to distinguish between a change in properties and a
change in structure. For example, User A doesn't need to know about a
change in properties for a node he is not currently looking at. However,
that same user will want to be told about any change to the overall tree
structure. So, I was thinking that any operations involving modifications
to the tree structure should set a "structure changed" flag in the database
(increment a counter). After any operation is performed, the client
compares its "changed" flag to the database value to see if it needs to
reload the tree structure.


Do you think this is workable?


Thanks.



Robin