HTTP vs MQTT trade-offs in IOT Protocols - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to show which protocol is typically more lightweight for IoT devices.

IOT Protocols

protocol = "[1]"  # More lightweight protocol for IoT

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

AHTTP

BSMTP

CFTP

DMQTT

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing HTTP because it is more common on the web.

MQTT is designed to be lightweight and efficient for IoT devices, unlike HTTP which is heavier.

2fill in blank

medium

Complete the code to select the protocol that uses a publish-subscribe model.

IOT Protocols

communication_model = "[1]"  # Model used by MQTT

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

AClient-server

BPeer-to-peer

CPublish-subscribe

DBroadcast

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing client-server with publish-subscribe.

MQTT uses a publish-subscribe model, where clients subscribe to topics and receive messages.

3fill in blank

hard

Fix the error in the statement about protocol reliability.

IOT Protocols

reliability = "[1]"  # Protocol with built-in message delivery guarantees

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

AMQTT

BHTTP

CUDP

DFTP

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing HTTP because it is reliable for web pages.

MQTT supports different Quality of Service levels for message delivery, making it more reliable for IoT messaging.

4fill in blank

hard

Fill both blanks to complete the comparison of protocol overhead and connection type.

IOT Protocols

protocol_overhead = "[1]"  # Lower overhead protocol
connection_type = "[2]"  # Protocol using persistent connections

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

AMQTT

BHTTP

CPersistent

DStateless

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up stateless and persistent connection types.

MQTT has lower overhead and uses persistent connections, while HTTP is stateless and has higher overhead.

5fill in blank

hard

Fill all three blanks to complete the dictionary comparing protocols by latency, security, and typical use case.

IOT Protocols

protocol_comparison = {
  "latency": "[1]",
  "security": "[2]",
  "use_case": "[3]"
}

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

ALow

BHigh

CIoT messaging

DWeb browsing

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing use cases or latency levels between protocols.

MQTT typically has low latency, high security options, and is used for IoT messaging, while HTTP is common for web browsing.

Practice

1. Which protocol is best suited for devices that need to send data only when requested and have simple communication?

easy

A. FTP

B. MQTT

C. HTTP

D. CoAP

Solution

1. Step 1: Understand HTTP communication style

   HTTP works on a request-response model where the client asks and the server replies, making it simple and direct.

2. Step 2: Compare with MQTT style

   MQTT uses publish-subscribe, which is more complex and suited for many devices and continuous data flow.

3. Final Answer:

   HTTP -> Option C

4. Quick Check:

   Request-response = HTTP [OK]

Hint: Request-response means HTTP, publish-subscribe means MQTT [OK]

Common Mistakes:

• Confusing MQTT as request-response
• Thinking HTTP supports many-to-many easily
• Mixing up protocol purposes

2. Which of the following is the correct way to describe MQTT's communication pattern?

easy

A. Publish-subscribe

B. Request-response

C. Peer-to-peer

D. Broadcast

Solution

1. Step 1: Identify MQTT communication model

   MQTT uses a publish-subscribe model where devices publish messages to topics and others subscribe to those topics.

2. Step 2: Eliminate other options

   Request-response is HTTP, peer-to-peer and broadcast are different models not used by MQTT.

3. Final Answer:

   Publish-subscribe -> Option A

4. Quick Check:

   MQTT = Publish-subscribe [OK]

Hint: MQTT always uses publish-subscribe pattern [OK]

Common Mistakes:

• Choosing request-response for MQTT
• Confusing peer-to-peer with publish-subscribe
• Assuming MQTT uses broadcast

3. Consider a network with many IoT sensors sending small updates frequently. Which protocol will likely reduce network bandwidth usage?

medium

A. HTTP because it uses simple requests

B. MQTT because it uses large message headers

C. HTTP because it supports caching

D. MQTT because it uses lightweight messages and persistent connections

Solution

1. Step 1: Analyze network usage for many devices

   MQTT uses small message headers and keeps connections open, reducing overhead for frequent messages.

2. Step 2: Compare with HTTP overhead

   HTTP opens a new connection per request with larger headers, increasing bandwidth use.

3. Final Answer:

   MQTT because it uses lightweight messages and persistent connections -> Option D

4. Quick Check:

   Low bandwidth = MQTT lightweight messages [OK]

Hint: Persistent connections save bandwidth in MQTT [OK]

Common Mistakes:

• Assuming HTTP is lighter due to caching
• Thinking MQTT has large headers
• Ignoring connection overhead

4. You have an IoT device that must send data only when triggered by a server. You try using MQTT but the device keeps sending data continuously. What is the likely mistake?

medium

A. Using MQTT publish-subscribe instead of HTTP request-response

B. Not configuring the device to subscribe to the server's trigger topic

C. Using HTTP instead of MQTT

D. Setting QoS level to 0

Solution

1. Step 1: Understand MQTT trigger mechanism

   MQTT devices receive triggers by subscribing to topics; without subscription, they can't wait for triggers.

2. Step 2: Identify why device sends continuously

   If not subscribed, device may publish data on its own schedule instead of waiting for server commands.

3. Final Answer:

   Not configuring the device to subscribe to the server's trigger topic -> Option B

4. Quick Check:

   MQTT triggers need subscriptions [OK]

Hint: MQTT triggers require subscription to server topic [OK]

Common Mistakes:

• Confusing publish-subscribe with request-response
• Thinking QoS affects trigger behavior
• Switching protocols unnecessarily

5. You want to design a system where thousands of sensors send data to a central server, but the network is unreliable and bandwidth is limited. Which protocol and feature combination is best?

hard

A. MQTT with persistent sessions and QoS 1 or 2

B. HTTP with frequent polling

C. HTTP with caching enabled

D. MQTT with QoS 0 and no session persistence

Solution

1. Step 1: Consider network constraints

   Unreliable network and limited bandwidth require efficient, reliable message delivery without repeated data loss.

2. Step 2: Evaluate protocol features

   MQTT supports persistent sessions to resume after disconnects and QoS 1 or 2 to ensure message delivery.

3. Step 3: Compare options

   HTTP polling wastes bandwidth and lacks delivery guarantees; MQTT QoS 0 and no persistence risk data loss.

4. Final Answer:

   MQTT with persistent sessions and QoS 1 or 2 -> Option A

5. Quick Check:

   Reliable delivery + low bandwidth = MQTT QoS 1/2 + persistence [OK]

Hint: Use MQTT QoS 1/2 with persistence for unreliable networks [OK]

Common Mistakes:

• Choosing HTTP for unreliable networks
• Using MQTT QoS 0 when reliability needed
• Ignoring session persistence