industrial//industrial data layer//event

Not everything should be stored as a continuous stream of samples. Some things happen once and are recorded as **events**: MotorStarted, PumpStopped, HighPressureAlarm, ValveFault.

Not everything should be stored as a continuous stream of samples. Some things happen once and are recorded as events: MotorStarted, PumpStopped, HighPressureAlarm, ValveFault.

Events feed analysis, maintenance, alarm management, traceability and diagnostics. They are the natural unit for "what happened during that shift", where a tag trend is the unit for "what value did it have at 18:03".

Alarms are events with a required human response and their own lifecycle (active, acknowledged, cleared). In a DCS alarm management is a discipline of its own; a badly rationalized alarm list floods operators during the one incident that matters.

On the data layer, events travel well over MQTT and OPC UA's alarms-and-conditions model, and they are the timeline that gives telemetry its context: the sample matters because of the event that framed it.