Message Count

Use this node to count how many messages pass through a rule chain over a fixed time interval — for example, tracking the throughput of telemetry messages per minute or auditing how many RPC calls arrive per hour. The count result is emitted as a POST_TELEMETRY_REQUEST message at the end of each interval.

• Interval in seconds — required. Duration of each counting window. At the end of each interval, the accumulated count is output and the counter resets.
• Output time series key prefix — required. Prefix for the telemetry key in the output message. The full key name is {prefix}_{serviceId}, where serviceId is the unique identifier of the rule engine service instance (e.g., tb-rule-engine1). This suffix enables distinguishing counts from different nodes in a clustered deployment.

1. On node startup, a counter is initialised to 0 and the first interval tick is scheduled.
2. For each incoming regular message: increment the counter by 1 and acknowledge the message immediately (the message does not continue down the rule chain).
3. On each interval tick:
   • Build a POST_TELEMETRY_REQUEST message with the current tenant as originator.
   • Set the message data to { "{prefix}_{serviceId}": <count> }.
   • Add metadata key delta containing the actual elapsed milliseconds since the last tick.
   • Reset the counter to 0.
   • Forward the generated message via Success.
   • Schedule the next tick.

State: service ID is tb-rule-engine1. Three messages arrive between t = 0 and t = 5 s.

{
  "interval": 5,
  "telemetryPrefix": "msgCount"
}

Output at t = 5 s — type: POST_TELEMETRY_REQUEST, originator: tenant.

Data:

{
  "msgCount_tb-rule-engine1": 3
}

Metadata:

{
  "delta": "5000"
}

Result: three messages were counted in the 5-second window; the counter resets for the next interval.

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "TbMsgCountNodeConfiguration",
  "type": "object",
  "required": ["interval", "telemetryPrefix"],
  "additionalProperties": false,
  "properties": {
    "interval": {
      "type": "integer",
      "description": "Time interval in seconds for counting messages."
    },
    "telemetryPrefix": {
      "type": "string",
      "description": "Prefix for the output telemetry key."
    }
  }
}