{
    "$id": "https://www.amwa.tv/event_and_tally/event_core.json",
    "$schema": "http://json-schema.org/draft-04/schema#",
    "description": "Message that gets sent out when the source state changes",
    "properties": {
        "identity": {
            "description": "Object describing event identity",
            "properties": {
                "flow_id": {
                    "description": "ID of the flow carrying the message",
                    "pattern": "^[0-9a-f]{8}-[0-9a-f]{4}-[1-5][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$",
                    "type": "string"
                },
                "source_id": {
                    "description": "ID of the source that holds the state that has changed",
                    "pattern": "^[0-9a-f]{8}-[0-9a-f]{4}-[1-5][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$",
                    "type": "string"
                }
            },
            "required": [
                "source_id"
            ],
            "type": "object"
        },
        "message_type": {
            "description": "A fixed string showing this is a state message",
            "pattern": "^state$",
            "type": "string"
        },
        "timing": {
            "description": "Object describing event timing",
            "properties": {
                "action_timestamp": {
                    "description": "String formatted TAI timestamp (<seconds>:<nanoseconds>) indicating when the state change described in the event took or will take place",
                    "pattern": "^[0-9]+:[0-9]+$",
                    "type": "string"
                },
                "creation_timestamp": {
                    "description": "String formatted TAI timestamp (<seconds>:<nanoseconds>) indicating when the message was created",
                    "pattern": "^[0-9]+:[0-9]+$",
                    "type": "string"
                },
                "origin_timestamp": {
                    "description": "String formatted TAI timestamp (<seconds>:<nanoseconds>) indicating when the message that triggered this message (if any) was created",
                    "pattern": "^[0-9]+:[0-9]+$",
                    "type": "string"
                }
            },
            "required": [
                "creation_timestamp"
            ],
            "type": "object"
        }
    },
    "required": [
        "identity",
        "timing",
        "event_type",
        "payload",
        "message_type"
    ],
    "title": "State change event",
    "type": "object"
}