EventRecord message in JSON format
{ "EventRecord":{ "id": , /*required, integer type, channel ID, e.g., 101, 102*/ "frontRecordTime": , /*optional, integer type, pre-recording time range when alarm is triggered or event occurred, unit: second*/ "afterRecordTime": /*optional, integer type, post-recording time range when alarm is triggered or event occurred, unit: second*/ } }