Event notification and filtering Henning Schulzrinne Columbia University

Event notification Core coordination tool for real-time decision making coordinating human availability distributing events of interest coordinating devices Lots of event notification systems for small or closed systems (e.g., SIENA, Gryphon) emphasis on large-scale message replication and routing Less emphasis on higher-level functions: composition of messages filtering access control

Internet event notification Assume relatively small fanout for each message (dozens) Domain-based publish/subscribe/notify Developed and standardized based on SIP/SIMPLE suite of protocols

Presence data architecture presence sources PUBLISH raw presence document privacy filtering create view (compose) depends on watcher XCAP select best source resolve contradictions XCAP composition policy privacy policy (not defined yet) draft-ietf-simple-presence-data-model

Presence data architecture candidate presence document raw presence document post-processing composition (merging) watcher filter remove data not of interest SUBSCRIBE difference to previous notification final presence document watcher NOTIFY

Objectives How to discover relevant and accessible (need-to-know) event sources? Composing events from tributary streams of events Aggregating event information over time avoid flooding incremental event updates, e.g., no need for 10m updates on location