MQTT with QoS levels in Raspberry Pi - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the MQTT QoS level to 1 when publishing a message.

Raspberry Pi

client.publish('sensor/data', payload='temperature', qos=[1])

Drag options to blanks, or click blank then click option'

A0

B2

C1

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using QoS 0 when message delivery guarantee is needed.

Using QoS 3 which is invalid.

The QoS level 1 ensures the message is delivered at least once.

2fill in blank

medium

Complete the code to subscribe to the topic 'home/livingroom' with QoS level 2.

Raspberry Pi

client.subscribe('home/livingroom', qos=[1])

Drag options to blanks, or click blank then click option'

A2

B1

C0

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using QoS 3 which is not a valid MQTT QoS level.

Confusing QoS 1 and QoS 2.

QoS 2 ensures the message is delivered exactly once, the highest level of guarantee.

3fill in blank

hard

Fix the error in the code to correctly publish a message with QoS 0.

Raspberry Pi

client.publish('alerts', payload='fire detected', qos=[1])

Drag options to blanks, or click blank then click option'

A1

B-1

C2

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using negative QoS values.

Using QoS 3 which is invalid.

QoS 0 means the message is sent once with no confirmation.

4fill in blank

hard

Fill both blanks to create a subscription with QoS 1 and publish a message with QoS 2.

Raspberry Pi

client.subscribe('devices/status', qos=[1])
client.publish('devices/status', payload='online', qos=[2])

Drag options to blanks, or click blank then click option'

A1

B0

C2

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using invalid QoS 3.

Mixing up QoS levels for subscribe and publish.

Subscription uses QoS 1 for at least once delivery, publishing uses QoS 2 for exactly once delivery.

5fill in blank

hard

Fill all three blanks to publish a message with QoS 1, subscribe with QoS 0, and publish another message with QoS 2.

Raspberry Pi

client.publish('alerts', payload='low battery', qos=[1])
client.subscribe('alerts', qos=[2])
client.publish('alerts', payload='battery critical', qos=[3])

Drag options to blanks, or click blank then click option'

A0

B1

C2

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using invalid QoS 3.

Confusing QoS levels between publish and subscribe.

The first publish uses QoS 1 for at least once delivery, subscription uses QoS 0 for no guarantee, and the second publish uses QoS 2 for exactly once delivery.