A system for processing triggering rules in SIP event notification filters, including an XPath processor configured to collect a set of XPath expressions from at least one trigger of at least one SIP event notification filter of at least one subscribers in a set of subscribers who are subscribed to state information of a resource, and create a merged finite state automaton having a plurality of nodes and transitions that collectively represent the combination of the XPath expressions, and a streaming parser configured to parse previously-published state information of the resource and newly-published state information of the resource, and stream parsing events of the parsed information to the XPath processor, where the XPath processor is configured to employ the automaton to perform a streaming evaluation of the XPath expressions in parallel to determine which nodes of the parsed information satisfies any of the XPath expressions represented by the automaton.