Fedora 4 provides options for developing event-driven architectures around the core system.
Fedora 4 can publish events on a JMS message queue.
Fedora 4 provides an "EventBus" for Fedora events.
Modeshape also has some tightly-integrated asynchronous operation machinery called Sequencers
ModeShape sequencers can automatically unlock the structured information buried within all of those files, and this useful content derived from your files is then stored back in the repository.