The multi-user shared persistent store makes it possible for two or
more programs (clients) to acces the same persistent store. Access to
the store has to be mediated through a server. The shared persistent store
consists of a number of frameworks that may be used to build clients
and servers. A client/server may contain part of the multi-user
functionality or all of it.
The following functionalty is supported
Concurrency control.
The Multi-User Shared Persistent Store implements a concurrency
control mechanism enabling several applications to simultaneously
access the same persistent store. During execution, these
applications may reget persistent objects to gain access to the
changes any of the other applications might have made to these objects.
Transactions.
If two applications access the same persistent store simultaneously,
race conditions may occur. To cope with this, the two processes have
to be synchronized.
This is supported by a locking mechanism, and with a transaction mechanism.
Notifications.
In order to enable coordination between cooperative applications, the
applications can be notified of events occurring in persistent stores,
the they have opened.