Avis is a multicast event bus.
BSEditor: AVIS is a multicast event bus. It provides a fast, publish/subscribe event routing service compatible with the commercial Elvin implementation developed by Mantara Software.

Elvin routers can be federated together to form wide-area event notification networks. Clients can exchange events with other clients anywhere on the bus, subscribing to messages using pattern-matching expressions that select messages based on their content.

Avis is a compatible drop-in replacement for Mantaras commercial elvind if quenching (for discovery of subscriptions) is not required. As of release 1.1, Avis supports federation with other Elvin-compatible routers.

Although Avis has not yet had the extensive optimisation and tuning that Mantaras commercial implementation has, for the majority applications this will not be an issue. you can free download Avis Event Router 1.1.2 now.