A method of determining an event instance in an event driven communications system, the method comprising the steps of: receiving (205, 207) an event stream, the event stream comprising a plurality of events; retrieving (203) metadata for each event of the received event stream; instantiating (219) an event instance for each event of the received event stream based on the retrieved metadata; reading (221) event data of each event of the received event stream into the instantiated event instance.