Fedora 4 provides many options for developing event-driven architectures around the core system.
HTTP APIs
At the HTTP level, Fedora 4 has two optional components, RSS feeds (pull) and Webhooks (push).
The RSS feed contains a list of recent events.
/fcr:rss
...
/fcr;webhooks
Message Queues
Fedora 4 can publish events on a JMS message queue.
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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.