System and method for providing a presence service

A system for providing a presence service, the system comprising:

• a Ruler for describing a requested publication operation of an Event Publication Agent (EPA) for target presence state information using a Publication Rule, sending the Publication Rule to an EPA responsible for publication of the target presence state information, updating or canceling the Publication Rule according to need, and sending a Publication Rule synchronization request to the EPA using an event package;
• an EPA for registering its publication capability on a set of presence state information to Session Initiation Protocol (SIP) Registrar using a Media Feature Tag, receiving and composing Publication Rules for the presence state information from the Ruler, performing publication to an Event-State Compositor (ESC) for the presence state information according to the composed Publication Rules, modifying the Publication Rule upon its update or cancel request from the Ruler, changing publication behavior to the ESC for the presence state information according to the modified Publication Rule, sending as a response message a most up-to-date Publication Rule to a Ruler who has requested the Publication Rule synchronization request using the event package, and notifying the Publication Rule synchronization requesting Ruler of further updates of the Publication Rule;
• and
• an SIP Registrar for registering an EPA with its publication capability on a set of presence information using the Media Feature Tag as requested by EPA, deciding the routing of a Publication Rule for target presence state information to the EPA responsible for publication of the target presence state information according to Media Feature Tag information as registered by the EPA.