I've been looking for some time for a good embedded database that
would work for desktop applications. Derby is ideal for that and I am
starting to use it more and more in various examples and tutorials
that I am writing for Cayenne. But there is one feature that I am
missing in Derby (or any other database for that matter) - an ability
to share the same database between multiple desktop applications (or
multiple VM instances of the same Java application).
I asked this question the Derby folks from Sun at ApacheCon in Dublin
the other day and the answer was basically - run the network server.
In other words db sharing and embedded mode are not compatible. So I
wonder what it would take to make it compatible?
Since we are talking desktop apps, the following conditions are at play:
(a) all apps run on the same machine (but in different VMs)
(b) usually only one instance at a time would work with the database,
but other instances can occasionally access the db in the background
(no need to deal with massive concurrency)
(c) usually the database is small-to-medium size.
Any ideas? One possible solution is cloning the DB for each instance
and using multicast for peer-to-peer synchronization.
Another (more promising) is to do collaborative peer-to-peer
connection pool (DataSource), so that when a client needs a local
Derby connection it sends a multicast so that current lock owner in a
different VM can finish its thing, shutdown Derby and release the
lock. I wonder if anyone has done that already?
Andrus
------------------------------
Andrus (aka Andrei) Adamchik
Cayenne Persistence Framework
Creator, Committer
http://incubator.apache.org/projects/cayenne.html
