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
Webhooks can be registered against the whole repository (or, maybe in the futures, subtrees). The endpoint will receive a POST request when an event is triggered with information about the event that triggered it.
/fcr;webhooks
Message Queues
Fedora 4 can publish events on a JMS message queue.
Java APIs
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
Webhooks
Fedora 4 provides fcrepo-webhooks as an optional module. Webhooks allows you to register a callback url as a lightweight means of acting on repository events.
fcrepo-irc provides a proof-of-concept application that uses Fedora's webhooks to post messages to an IRC channel when a repository event occurs.
fcrepo-kitchen-sink includes fcrepo-webhooks (along with all the other optional modules).
