{"draft":"draft-ietf-sipcore-subnot-etags-04","doc_id":"RFC5839","title":"An Extension to Session Initiation Protocol (SIP) Events for Conditional Event Notification","authors":["A. Niemi","D. Willis, Ed."],"format":["ASCII","HTML"],"page_count":"25","pub_status":"PROPOSED STANDARD","status":"PROPOSED STANDARD","source":"Session Initiation Protocol Core RAI","abstract":"The Session Initiation Protocol (SIP) events framework enables\r\nreceiving asynchronous notification of various events from other SIP\r\nuser agents.  This framework defines the procedures for creating,\r\nrefreshing, and terminating subscriptions, as well as fetching and\r\nperiodic polling of resource state.  These procedures provide no\r\ntools to avoid replaying event notifications that have already been\r\nreceived by a user agent.  This memo defines an extension to SIP\r\nevents that allows the subscriber to condition the subscription\r\nrequest to whether the state has changed since the previous\r\nnotification was received.  When such a condition is true, either the\r\nbody of a resulting event notification or the entire notification\r\nmessage is suppressed.  [STANDARDS-TRACK]","pub_date":"May 2010","keywords":["[--------]","SIP events","subnot-etags","optimization"],"obsoletes":[],"obsoleted_by":[],"updates":[],"updated_by":[],"see_also":[],"doi":"10.17487\/RFC5839","errata_url":null}