Hi,
I am currently working on converting our client/server application from an MS
Access database to using Derby. We have approximately 40 sites that use our
software and each one can have from 1 to 10 client computers that connect to
the central database.
The latest issue I have come across is how to handle the application and
database upgrades at our client sites.
Our current process is automated and works like this:
1. Check on our website to see if there is a new release available
2. If there is a new release available, download the new client application
and the scripts to upgrade the database
3. Determine if anyone is currently connected to the database prior to
performing the upgrade so we are not altering tables while someone is doing
work.
4. If anyone is connected to the database we abort the upgrade and inform
the user that they should make sure all other users are disconnected before
performing the upgrade.
5. If there are no users connected to the database then we rename the
Access file so that no users can connect to the database while we're performing
the upgrade.
6. Perform the database upgrade.
7. Rename the Access database file back to it's original name so it is
available for use again.
8. Upgrade the client application files.
Currently we are able to determine if anyone is connected to the Access
database by just trying to rename the .mdb file. If this fails then the
database is in use. I have been unable to find a good way to determine if
there are any users currently connected to the Derby database. I have found
mentions of calling NetworkServerControl runtimeinfo and looking at the Active
Sessions, but I don't know of a way to call that function and return the Active
Sessions results to the installer program that I am using (Indigo Rose
TrueUpdate).
Is there any other method for determining the number of users that are
currently connected to a Derby database?
Also, is there a way to lock the database so that no users can connect to it
while the upgrade is being performed?
Is there anyone else that has a similar type of situation, and how did you
handle it?
Thanks,
Brad
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