Event types
- Last UpdatedAug 19, 2026
- 1 minute read
Event types describe items that happen over a period of time, usually to an entity, such as alarms, operational issues or changes in state. Usually these items have a clear starting point.
Similar to entity types, event types are defined in Schema messages as type definitions. You define an event type by setting its classification to event. In the schema, this specifies the information that the event carries, such as its properties and how it relates to other types. It does not send event data.
Event types usually:
-
Include properties that describe what the event is or what’s happening
-
Are meant to capture timing information, such as when the event starts and ends
-
Are often tied to one or more entities
Actual event data is sent using Instance messages. In those messages, events appear in the Events array. Each event instance can include lifecycle details like start time and end time, and it can be linked to related entities or data streams using relationships defined in the schema.
The following event type example illustrates how an event such as a high pressure alarm can relate to an entity type:
{
"types": [
{
"id": "HighPressureAlarm",
"classification": "event",
"properties": {
"AlarmId": {
"type": "string",
},
"Severity": {
"type": "integer"
},
"Message": {
"type": "string"
}
}
},
{
"id": "CylindricalTank",
"classification": "entity",
"properties": {
"TankId": {
"type": "string",
},
"Model": {
"type": "string"
}
}
}
],
"relationships": [
{
"source": {
"collection": "types",
"id": "HighPressureAlarm"
},
"target": {
"collection": "types",
"id": "CylindricalTank"
}
}
]
}