Entities

Entity instances represent items in the data model, such as assets, equipment, locations, or systems. The schema describes the entity while the instance message show what entities exist and captures their details.

They are published using Instance messages, where they appear in the Entities array. Each entry in the array represents a single entity instance and identifies:

• The entity type it is based on (typeid)

• A unique identifier for the instance (id)

• Optional descriptive information such as name, description, tags, or metadata

• Property values defined by the entity type in the schema

Instance messages do not redefine structure. All entity instances should have an entity type that has already been defined in a Schema message.

Entity instances may also be linked to other entities, events, or streaming data through instance relationships. These relationships must follow the relationship patterns established at the schema level and are included in the Relationships array of the same or a separate Instance message.

To illustrate an entity instance, the following example shows a single entity instance that was created from an entity type defined in the schema:

{

"entities": [

{

"typeid": "CylindricalTank",

"id": "Plant2.Tank1",

"name": "Tank 1",

"description": "Primary tank in the Windtopia plant",

"datasource": "Windtopia PI",

"properties": {

"Serial": "5236-3523-KKF4",

"Model": "FN-2187",

"TankDiameter": 75,

"TankHeight": 50,

"Inventory": {

"Serial": "PP23-P2234-KLM",

"Model": "PS-2234",

"Manufacturer": "Schneider Electric",

"ManufactureDate": "2022-08-25"

}

}

}

]

}

The following example creates two typed components for the same entity.

omfversion: 2.0

messagetype: instance

action: create

messageformat: json

{

"entities": [

{

"typeid": "TankAsset",

"id": "Tank-101",

"name": "Tank 101",

"datasource": "Plant-A-Asset-System",

"value": {

"SerialNumber": "TK-101-2026",

"Model": "ST-5000",

"Capacity": 5000.0

}

},

{

"typeid": "InventoryRecord",

"id": "Tank-101",

"name": "Tank 101",

"datasource": "Corporate-Inventory-System",

"value": {

"InventoryNumber": "INV-004218",

"Manufacturer": "Example Industrial",

"ManufactureDate": "2022-08-25"

}

}

]

}