JSON format from Cloud Injector Modules

The Cloud Injector Modules publish data in a JSON format with each message comprising a Topic and Payload.

The Topic contains the following key/value pairs:

• namespace
  • Set as "spBv1.0"
• edgeNodeDescriptor
  • The combination of the Group ID and Edge Node ID which provides a unique identifier for the Edge Node
• groupId
  • The Group ID
• edgeNodeId
  • The Edge Node ID
• deviceId
  • The Device ID
• type
  • Message type including:
    • NBIRTH
    • DBIRTH
    • DDATA
    • NDEATH
    • DDEATH

The Payload contains the following key/value pairs:

• timestamp
  • The time stamp that the payload was created
• metrics
  • An array containing data specific to the message type being published
  • Each object in the array will include the following name/value pairs:
    • name
    • timestamp
    • dataType
    • value
  • Additional name/value pairs in the DBIRTH or NBIRTH messages only include:
    • metaData ****
    • properties
      • The Quality property. See the Ignition Tag Property Enum Reference for the Data Quality value reference
      • Additional property values such as engHigh, engLow etc are included if they have been changed from the Ignition default. See the Ignition Tag Properties reference for all available properties.
• seq
  • The message sequence number used to ensure that messages are processed in the correct order

Sample JSON messages

Using a simple tag tree structure shown below, we can show how these JSON formatted messages will be generated:

NBIRTH

The Edge Node BIRTH message will contain a Topic and Payload:

• Topic
  • Namespace
  • Edge Node Descriptor
  • Group ID
  • Edge Node ID
  • Message Type
• Payload
  • Timestamp
  • Metrics array containing 
    • A Birth/Death sequence number to track the Sparkplug session of the Edge client
    • Any Edge Node tags defined in the Edge Node folder
  • Seq 

{
  "topic": {
    "namespace": "spBv1.0",
	"edgeNodeDescriptor": "G1/E1",
    "groupId": "G1",
    "edgeNodeId": "E1"
	"type": "NBIRTH"
  },
  "payload": {
    "timestamp": 1638223073190,
    "metrics": [
      {
        "name": "bdSeq",
        "timestamp": 1638223073187,
        "dataType": "Int64",
        "value": 5
      },
	  {
        "name": "Tag 4",
        "timestamp": 1638223073156,
        "dataType": "Int32",
        "metaData": {},
        "properties": {
             "Quality": {
                 "type": "Int32",
                 "value": 192
			 }
        },
        "value": 100
      {,

    ],
    "seq": 0
  }
}

DBIRTH

The Device BIRTH message will contain the following:

• The Sparkplug elements: Namespace, Group ID, Edge Node ID, Device ID.  They will be grouped under "topic" along with Message Type
• A "timestamp" for when the payload was constructed
• Any Device tags defined in the Device folder
• A message sequence number

{
  "topic": {
      "namespace": "spBv1.0",
      "edgeNodeDescriptor": "G1/E1",
      "groupId": "G1",
      "edgeNodeId": "E1",
      "deviceId": "D1",
      "type": "DBIRTH"
  },
  "payload": {
    "timestamp": 1638223073192,
    "metrics": [
        {
            "name": "T1",
            "timestamp": 1638223073192,
            "dataType": "Int32",
            "metaData": {},
            "properties": {
                "Quality": {
                    "type": "Int32",
                    "value": 192
                }
            },
            "value": 12
        }
    ],
    "seq": 1
  }
}

DDATA

The Device DDATA message will contain the following:

• The Sparkplug elements: Namespace, Group ID, Edge Node ID, Device ID.  They will be grouped under "topic" along with Message Type
• A "timestamp" for when the payload was constructed
• Any Device tags defined in the "Device folder that have changed
• A message sequence number

{
  "topic": {
    "namespace": "spBv1.0",
	"edgeNodeDescriptor": "G1/E1",
    "groupId": "G1",
    "edgeNodeId": "E1",
    "deviceId": "D1"
	"type": "DDATA"
  },
  "payload": {
    "timestamp": 1638223663812,
    "metrics": [
      {
        "name": "T1",
        "timestamp": 1638223662800,
        "dataType": "INT32",
        "value": 100
      }
    ],
    "seq": 2
  }
}

NDEATH

DDEATH

Understanding and decoding Ignition QualityCodes