Other characteristics
security support (e.g., for subscriber registration & notification delivery, and for publisher registration, ...)
inter-mediation support (one or several event channels & federations thereof)
application-level quality of service support
- expiration times (subscription leases, event time outs)
- priorities of events
- communication & channel reliability (best-effort, at-least-once, at-most-once, exactly-once)
- persistence (of events)
logging facilities (e.g., to capture event histories)