Rule engine for IoT data routing in IOT Protocols - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Rule Engine Conditions

In an IoT rule engine, which condition correctly routes temperature sensor data only when the temperature exceeds 30°C?

A temperature > 30

B temperature >= 30

C temperature == 30

D temperature < 30

💡 Hint

Think about the condition that triggers only when temperature is strictly greater than 30.

The condition temperature > 30 routes data only when the temperature is above 30°C, excluding 30 itself.

💻 Command Output

intermediate

Output of Rule Engine Log Command

What is the output of the command show rules status if the rule engine has 3 active rules and 1 disabled rule?

A No rules found

B Rules active: 4\nRules disabled: 0

C Active rules: 1\nDisabled rules: 3

D Active rules: 3\nDisabled rules: 1

💡 Hint

The output lists counts of active and disabled rules separately.

The command shows the count of active and disabled rules separately. Since there are 3 active and 1 disabled, option D matches.

❓ Configuration

advanced

Correct Rule Syntax for MQTT Topic Routing

Which configuration snippet correctly routes messages from topic sensor/temperature to alerts/high_temp when temperature is above 50?

A

rule {
  when topic == 'sensor/temperature' and payload.temperature > 50
  then send 'alerts/high_temp'
}

B

rule {
  if topic = 'sensor/temperature' and temperature > 50
  then send to 'alerts/high_temp'
}

C

rule {
  when topic == 'sensor/temperature' and payload.temperature > 50
  then publish 'alerts/high_temp'
}

D

rule {
  when topic = 'sensor/temperature' and payload.temperature > 50
  then publish 'alerts/high_temp'
}

💡 Hint

Check for correct use of 'when', 'then', and equality operators.

Option C uses correct syntax: 'when' with '==' for topic, accesses payload.temperature, and uses 'then publish' to route.

❓ Troubleshoot

advanced

Troubleshooting Rule Engine Message Loss

A rule engine is dropping messages unexpectedly. Which is the most likely cause?

A The rule condition filters out all incoming messages

B The MQTT broker is offline

C The rule engine has too many active rules

D The device sending data is powered off

💡 Hint

Consider what happens if no messages match the rule condition.

If the rule condition filters out all messages, none are routed, causing apparent message loss.

🔀 Workflow

expert

Order of Steps to Deploy a New IoT Data Routing Rule

Arrange the steps in the correct order to deploy a new rule that routes humidity data above 70% to an alert topic.

A 1,3,2,4

B 1,2,3,4

C 2,1,3,4

D 3,1,2,4

💡 Hint

Think about writing, testing, deploying, then monitoring.

The correct workflow is to first write the rule, then test it, deploy it, and finally monitor logs for issues.