Patent ID: 8903820

Claim:
A method, comprising: receiving a session initiation protocol subscribe message at a session initiation protocol event server from a user device, the session initiation protocol subscribe message being for a subscription to an event package comprised of a single event, where the session initiation protocol subscribe message comprises a message header specifying a resource query event identifier and a message body that comprises a resource query formulated in a query language, the resource query operating on resource data available at at least one of the session initiation protocol event server and through the session initiation protocol event server; determining if the subscription can be granted by parsing semantic information contained in the message body of the session initiation protocol subscribe message and, based on the parsed semantic information, determining using at least an aggregation of existing resource state information a list of resources that are a priori unknown at the user device and that fulfill constraints of the resource query during a lifetime of the subscription, where the list of resources that are a priori unknown at the user device comprises a plurality of resources; sending the determined list of resources that fulfill constraints of the resource query to the user device as a start state of the subscription; and during the lifetime of the subscription sending a notification to the user device in response to a change occurring in the determined list of resources.