client-certs

Example TCK compliant Sparkplug B Host Application

This example demonstrates how this package might be used to connect to a MQTT Broker using client certificates in order to read and write metrics.

To run it you can use:

go run . <flags>:

  -broker-url string
        URL of the mqtt broker. E.g., ssl://localhost:1883 (Required)
  -cert string
        Path to the client certificate file (Required)
  -device-id string
        Only log messages from this device ID (Optional)
  -edge-node-id string
        Only log messages from this edge node ID (Optional)
  -group-id string
        Only log messages from this group ID (Optional)
  -host-id string
        This ID will be used as the client ID for the MQTT connection (Required)
  -key string
        Path to the private key file (Required)
  -metric-name string
        Only log messages for this metric (Optional)

Reading metrics

The application will connect to the MQTT Broker and listen for BIRTH and DATA messages, logging them to std out like:

time=2023-11-15T20:22:57.647-05:00 level=INFO msg="Received metric callback" metric_name=WriteableDouble2 edge_node_descriptor=TestGroup/E0 metric_type=Double device_id=Writeable quality=GOOD value=&{DoubleValue:789}

It also handles message reordering and will send Node Control/Rebirth requests in the event of invalid or out of order messages.

Writing metrics

The application is also capable of sending NCMD and DCMD messages to change the value of metrics. In order to do this it will start a simple http server on port 8080 with 4 endpoints:

• /send-edge-node-rebirth-request
• /send-device-rebirth-request
• /write-edge-node-metric
• /write-device-metric

All of them take the same 3 query parameters to determine which Edge Node or Device to send the command to:

• group_id
• edge_node_id
• device_id (not needed if sending an Edge Node command)

Examples

Writing device metrics of different types:

$> curl --json '[{"name":"WriteableDouble2","value":15.4, "data_type": "Double"}]' "localhost:8080/write-device-metric?group_id=TestGroup&edge_node_id=E0&device_id=Writeable"

$> curl --json '[{"name":"WriteableBoolean1","value":true, "data_type": "Boolean"}]' "localhost:8080/write-device-metric?group_id=TestGroup&edge_node_id=E0&device_id=Writeable"

$> curl --json '[{"name":"WriteableInteger1","value":10, "data_type": "Int32"}]' "localhost:8080/write-device-metric?group_id=TestGroup&edge_node_id=E0&device_id=Writeable"

Request a node rebirth:

curl -X POST "localhost:8080/send-edge-node-rebirth-request?group_id=TestGroup&edge_node_id=E0"

Request a device rebirth:

curl -X POST "localhost:8080/send-device-rebirth-request?group_id=TestGroup&edge_node_id=E0&device_id=Writeable"