1. An Event Model for Internet Services Subscribe/Unsubscribe Post e e e e CHANNEL e1 e2 e3 e FILTER RPC (Work) e Push Pull TRANSDUCER SINK e Interface: postIF: method: post(event e) Filter: implements postIF() methods: filter (postIF), post(event) Transducer: implements postIF methods: post(event) Channel: implements postIF(), methods: subscribe(postIF), unsubscribe(token), last()->event, post(event) Sink: uses postIF

2. Notes Filters can do aggregation before posting Filters can subscribe to many channels Meta-channel creates channels and advertises to SDS Events can be strongly or weakly typed Channel does access control of posts Subscribers can unsubscribe themselves through token-based capability Channel assigns locally unique sequence number to events, serializes them

3. Open Questions and Applications How many events need to be stored in a channel? Can we have persistent channel service? Can SDS use event delivery model to advertise services? Can easily integrate event delivery in Ninja Mail to provide persistent subscription