Skip to content

Sensor-Data-Router.md

Latest commit

 

History

History
106 lines (74 loc) · 3.5 KB

Sensor-Data-Router.md

File metadata and controls

106 lines (74 loc) · 3.5 KB
title Sensor Data Router
category Action
version 1.0.0
last_updated 2025-10-25
description Route sensor data using wildcards to extract sensor IDs and create structured topic hierarchies
related_tutorials Tutorial/01-basics/topic-actions.lotnb

Sensor Data Router

Overview

The Sensor Data Router pattern demonstrates how to use wildcard topics (+) to match multiple sensors and extract context from the topic structure using TOPIC POSITION. This enables scalable, context-aware data routing for any number of sensors.

Pattern

DEFINE ACTION SensorDataRouter
ON TOPIC "sensors/+/temperature" DO
    SET "sensor_id" WITH TOPIC POSITION 1
    
    PUBLISH TOPIC "processed/temperature/" + {sensor_id} WITH PAYLOAD
    PUBLISH TOPIC "processed/temperature/" + {sensor_id} + "/timestamp" WITH TIMESTAMP "UTC"

How It Works

  1. Wildcard Matching: sensors/+/temperature matches any sensor ID in the middle position
  2. Context Extraction: TOPIC POSITION 1 extracts the sensor ID (0-indexed positions)
  3. Dynamic Routing: Routes data to sensor-specific processed topics
  4. Timestamp Addition: Adds timestamps for data tracking

Topic Position Indexing

For topic sensors/temp001/temperature:

  • TOPIC POSITION 0 = "sensors"
  • TOPIC POSITION 1 = "temp001"
  • TOPIC POSITION 2 = "temperature"

Expected MQTT Topics

Input Topics (Wildcard Pattern)

  • sensors/temp001/temperature - Temperature from sensor temp001
  • sensors/temp002/temperature - Temperature from sensor temp002
  • sensors/pressXYZ/temperature - Temperature from any sensor

Output Topics (Dynamic)

  • processed/temperature/{sensor_id} - Processed temperature reading
  • processed/temperature/{sensor_id}/timestamp - Processing timestamp

Example Payloads

Publish to: sensors/temp001/temperature
Payload: 25.5

Results:

  • processed/temperature/temp001: 25.5
  • processed/temperature/temp001/timestamp: "2025-10-25T14:30:15Z"

Use Cases

  • Multi-Sensor Systems: Handle any number of sensors with one action
  • Data Normalization: Transform raw sensor topics to standardized structure
  • Timestamp Tracking: Add processing timestamps for audit trails
  • Topic Namespace Mapping: Route from raw to processed topic hierarchies

Variations

Multi-Level Sensor Hierarchy

DEFINE ACTION MultiLevelSensorRouter
ON TOPIC "factory/+/+/temperature" DO
    SET "line_id" WITH TOPIC POSITION 1
    SET "machine_id" WITH TOPIC POSITION 2
    
    PUBLISH TOPIC "processed/" + {line_id} + "/" + {machine_id} + "/temperature" WITH PAYLOAD
    PUBLISH TOPIC "processed/" + {line_id} + "/" + {machine_id} + "/timestamp" WITH TIMESTAMP "UTC"

Matches topics like: factory/line1/machine5/temperature

Router with Data Transformation

DEFINE ACTION TemperatureConverter
ON TOPIC "sensors/+/temperature/celsius" DO
    SET "sensor_id" WITH TOPIC POSITION 1
    
    SET "fahrenheit" WITH (PAYLOAD * 9 / 5 + 32)
    
    PUBLISH TOPIC "sensors/" + {sensor_id} + "/temperature/fahrenheit" WITH {fahrenheit}
    PUBLISH TOPIC "sensors/" + {sensor_id} + "/temperature/both" WITH "C: " + PAYLOAD + ", F: " + {fahrenheit}

Demonstrates: Unit conversion during routing

Related Patterns

Back to Actions