Optimizing Notifications for Presence Network Agents
draft-rosen-simple-watcher-count-00

Abstract

In large presence systems deployed in multiservice networks, presence information is often known by the network in addition to, or instead of the presentity's devices (endpoints). Examples of such information include location and availability for various kinds of session establishment. Even if devices know the information, the network often has more bandwidth and better scale to keep the presence server up to date. A Presence Network Agent (PNA) can publish presence information to a Presence Server(PS). When done large scale, the basic publish operation can be inefficient. When the network has millions of subscribers, only some of which have watchers, blind Publish operations are unecessary. WINFO can be used to determine watchers, but the efficiency of maintaining WINFO per subscriber, and the size of the messages involved, make that solution unattractive. The PNA would prefer to have the Presence Server simply tell it when there was at least one watcher. This document describes an XML document stored on the PS by which the PNA maintains a list of subscribers it can provide presence for as a SIP event package that tells the PNA when the number of watchers for a presentity on the list (or a specific presence element for a presentity) goes from 0 to at least 1 or from 1 to 0.

Authors

Brian Rosen
Salvatore Loreto
Krisztian Kiss

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