QoS levels (0, 1, 2) in IOT Protocols - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the MQTT message QoS level to 1.

IOT Protocols

client.publish(topic, message, qos=[1])

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A2

B1

C0

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using QoS 0 when delivery guarantee is needed

Using invalid QoS level 3

QoS level 1 means the message is delivered at least once, ensuring delivery but possibly duplicates.

2fill in blank

medium

Complete the code to set the MQTT client to receive messages with QoS level 2.

IOT Protocols

client.subscribe(topic, qos=[1])

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A2

B0

C1

D4

Attempts:

3 left

💡 Hint

Common Mistakes

Using QoS 1 instead of 2 for exactly once delivery

Using invalid QoS level 4

QoS level 2 ensures exactly once delivery, the highest guarantee in MQTT.

3fill in blank

hard

Fix the error in the QoS level assignment to ensure valid MQTT QoS.

IOT Protocols

qos_level = [1]

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A1

B3

C-1

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Using QoS levels outside 0-2

Negative QoS values

Valid MQTT QoS levels are 0, 1, or 2. 1 is a valid choice.

4fill in blank

hard

Fill both blanks to create a dictionary mapping QoS levels to their descriptions.

IOT Protocols

qos_descriptions = {0: '[1]', 2: '[2]'}

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AAt most once delivery

BAt least once delivery

CExactly once delivery

DNo delivery guarantee

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up QoS 0 and 2 descriptions

Using 'At least once' for QoS 0

QoS 0 means at most once delivery (no guarantee), QoS 2 means exactly once delivery.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension filtering QoS levels greater than 0.

IOT Protocols

filtered_qos = {level: desc for level, desc in qos_descriptions.items() if level [1] [2] and desc != '[3]'}

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A>

B0

CAt most once delivery

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>'

Filtering with wrong description string

This comprehension keeps QoS levels greater than 0 and excludes 'At most once delivery'.