DE6412 Computer Programming 2 - Task 4

Part B: Workflow Development (LO2)

Step 4: Create the n8n Workflow

Access n8n interface (usually at http://localhost:5678) and create a new workflow with the following components:

4.1: Add Schedule Trigger

Add a Schedule Trigger node to call the API every 5 seconds:

• Search for "Schedule Trigger" in the node panel
• Set Trigger Interval to "Seconds"
• Set Seconds Between Triggers to 5

4.2: Add HTTP Request Node

Add an HTTP Request node to fetch temperature data:

• Set Method to GET
• Set URL to: https://fakerapi.it/api/v2/custom?_quantity=1&sensor_voltage=longitude&sensor_current=longitude
• Set Response Format to JSON

4.3: Add Code Node for Temperature Analysis

Add a Code node to analyze temperature readings and detect anomalies:

// Temperature analysis code for n8n Code node
const inputData = $input.all();

for (const item of inputData) {
  const sensorData = item.json.data[0];
  const sensor1_temp = sensorData.sensor_voltage;
  const sensor2_temp = sensorData.sensor_current;
  
  // Check if temperatures are within safe range (-100 to +100)
  const sensor1_alert = sensor1_temp < -100 || sensor1_temp > 100;
  const sensor2_alert = sensor2_temp < -100 || sensor2_temp > 100;
  
  // Prepare output data
  const outputItem = {
    timestamp: new Date().toISOString(),
    sensor1_temperature: sensor1_temp,
    sensor2_temperature: sensor2_temp,
    sensor1_status: sensor1_alert ? 'ALERT' : 'NORMAL',
    sensor2_status: sensor2_alert ? 'ALERT' : 'NORMAL',
    alert_required: sensor1_alert || sensor2_alert,
    alert_message: ''
  };
  
  // Generate alert message if needed
  if (outputItem.alert_required) {
    let alertMsg = '🚨 TEMPERATURE ALERT 🚨\n';
    if (sensor1_alert) {
      alertMsg += `Sensor 1: ${sensor1_temp.toFixed(2)}°C (OUT OF RANGE)\n`;
    }
    if (sensor2_alert) {
      alertMsg += `Sensor 2: ${sensor2_temp.toFixed(2)}°C (OUT OF RANGE)\n`;
    }
    alertMsg += `Safe Range: -100°C to +100°C\nTime: ${outputItem.timestamp}`;
    outputItem.alert_message = alertMsg;
  }
  
  $return.push({json: outputItem});
}
        

4.4: Add IF Node for Conditional Logic

Add an IF node to check if an alert is required:

• Set Condition to "Boolean"
• Set Value 1 to {{$json.alert_required}}
• Set Operation to "Equal"
• Set Value 2 to true

4.5: Add Telegram Node

Add a Telegram node connected to the "True" output of the IF node:

• Set Resource to "Message"
• Set Operation to "Send Text Message"
• Set Bot Token to your bot token from Step 3
• Set Chat ID to your chat ID from Step 3
• Set Text to {{$json.alert_message}}

Step 5: Test and Deploy the Workflow

Test your workflow by manually executing it and then activate it for continuous monitoring:

1. Click "Execute Workflow" to test manually
2. Verify that data flows through all nodes correctly
3. Check that you receive test messages in Telegram when alerts occur
4. Click "Active" toggle to enable automatic execution