HTTP request methods for IoT (GET, POST, PUT) in IOT Protocols - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the GET method do in HTTP requests for IoT devices?

GET requests ask the server to send back data. In IoT, it is used to read sensor data or device status without changing anything.

beginner

Explain the purpose of the POST method in IoT HTTP communication.

POST sends new data to the server. IoT devices use POST to send sensor readings or events to a server for storage or processing.

intermediate

What is the difference between PUT and POST methods in IoT HTTP requests?

PUT updates or replaces existing data on the server, while POST adds new data. PUT is idempotent, meaning repeating it has the same effect as once.

intermediate

Why is the PUT method considered idempotent in IoT HTTP requests?

Because sending the same PUT request multiple times results in the same server state. This helps avoid unintended changes in IoT device data.

beginner

Give a simple example of when an IoT device would use a POST request.

An IoT temperature sensor sends a POST request to the server every minute with the latest temperature reading to log data.

Which HTTP method is used by an IoT device to retrieve data without changing it?

A GET

B POST

C PUT

D DELETE

GET requests are used to read or retrieve data without modifying it.

What does the POST method do in IoT HTTP communication?

A Deletes data on the server

B Updates existing data on the server

C Retrieves data from the server

D Sends new data to the server

POST sends new data, such as sensor readings, to the server.

Which HTTP method is idempotent and used to update or replace data in IoT?

A GET

B PUT

C POST

D PATCH

PUT is idempotent and updates or replaces existing data.

If an IoT device sends the same PUT request multiple times, what happens?

A The server deletes the data

B The server data changes each time

C The server data remains the same after the first request

D The server rejects the request

PUT is idempotent, so repeated requests do not change the server state after the first update.

Which HTTP method would an IoT device use to send a new sensor reading to a server?

A POST

B GET

C PUT

D HEAD

POST is used to send new data like sensor readings to the server.

Describe the roles of GET, POST, and PUT HTTP methods in IoT device communication.

Think about reading, creating, and updating data.

Explain why idempotency of the PUT method is important for IoT devices.

Consider what happens if a device sends the same update multiple times.

Practice

1. Which HTTP method is used to retrieve data from an IoT device without changing it?

easy

A. POST

B. DELETE

C. PUT

D. GET

Solution

1. Step 1: Understand the purpose of GET

   GET is designed to fetch or read data without modifying it on the server or device.

2. Step 2: Compare with other methods

   POST sends new data, PUT updates existing data, DELETE removes data. Only GET fetches without change.

3. Final Answer:

   GET -> Option D

4. Quick Check:

   GET = fetch data without change [OK]

Hint: GET fetches data, POST sends new, PUT updates existing [OK]

Common Mistakes:

• Confusing POST with GET as both send data
• Thinking PUT fetches data
• Using DELETE instead of GET for retrieval

2. Which of the following is the correct syntax to send data using POST method in an HTTP request for IoT?

easy

A. PUT /device/data HTTP/1.1\nContent-Type: application/json\n\n{"temp": 22}

B. POST /device/data HTTP/1.1\nContent-Type: application/json\n\n{"temp": 22}

C. GET /device/data HTTP/1.1\nContent-Type: application/json\n\n{"temp": 22}

D. DELETE /device/data HTTP/1.1\nContent-Type: application/json\n\n{"temp": 22}

Solution

1. Step 1: Identify the method for sending new data

   POST is used to send new data to the server or device, so the request line must start with POST.

2. Step 2: Check the syntax correctness

   The syntax includes the method, path, HTTP version, headers, and body. POST /device/data HTTP/1.1\nContent-Type: application/json\n\n{"temp": 22} correctly uses POST with JSON data.

3. Final Answer:

   POST /device/data HTTP/1.1\nContent-Type: application/json\n\n{"temp": 22} -> Option B

4. Quick Check:

   POST sends data with correct syntax [OK]

Hint: POST method starts the request line to send data [OK]

Common Mistakes:

• Using GET method to send data
• Missing Content-Type header
• Using DELETE or PUT instead of POST for new data

3. Given this HTTP request to update a device setting:

PUT /device/settings HTTP/1.1\nContent-Type: application/json\n\n{"mode": "eco"}

What is the expected result on the device?

medium

A. The device mode is updated to 'eco'.

B. The device sends back current settings without change.

C. A new device setting is created without replacing existing ones.

D. The device deletes the current settings.

Solution

1. Step 1: Understand the PUT method purpose

   PUT replaces or updates existing data on the device with the provided data.

2. Step 2: Analyze the request body

   The JSON body sets "mode" to "eco", so the device's mode setting will be updated accordingly.

3. Final Answer:

   The device mode is updated to 'eco'. -> Option A

4. Quick Check:

   PUT updates existing data [OK]

Hint: PUT updates or replaces existing data on device [OK]

Common Mistakes:

• Thinking PUT only adds new data without replacing
• Confusing PUT with GET which fetches data
• Assuming DELETE is used to update data

4. You wrote this HTTP request to update sensor data:

POST /sensor/data HTTP/1.1\nContent-Type: application/json\n\n{"humidity": 45}

But the device does not update the data. What is the likely error?

medium

A. The JSON body is invalid.

B. Content-Type header is missing.

C. POST is incorrect; PUT should be used to update existing data.

D. GET method should be used instead of POST.

Solution

1. Step 1: Identify the purpose of the request

   The request aims to update existing sensor data, which requires the PUT method.

2. Step 2: Check the method used

   POST is for sending new data, not updating. Using POST here causes the device to ignore the update.

3. Final Answer:

   POST is incorrect; PUT should be used to update existing data. -> Option C

4. Quick Check:

   Use PUT to update data, not POST [OK]

Hint: Use PUT to update, POST to create new data [OK]

Common Mistakes:

• Using POST instead of PUT for updates
• Ignoring Content-Type header importance
• Confusing GET with POST for data changes

5. An IoT device API supports GET, POST, and PUT methods. You want to add a new temperature reading and then update the device's configuration mode. Which sequence of HTTP requests should you use?

hard

A. POST to add temperature, then PUT to update configuration

B. PUT to add temperature, then POST to update configuration

C. GET to add temperature, then PUT to update configuration

D. POST to add temperature, then POST to update configuration

Solution

1. Step 1: Identify method for adding new data

   POST is used to send new data, so adding a temperature reading requires POST.

2. Step 2: Identify method for updating existing data

   PUT updates or replaces existing data, so updating configuration mode requires PUT.

3. Step 3: Determine correct sequence

   First POST to add new reading, then PUT to update configuration.

4. Final Answer:

   POST to add temperature, then PUT to update configuration -> Option A

5. Quick Check:

   POST new data, PUT update existing [OK]

Hint: POST adds new, PUT updates existing; order matters [OK]

Common Mistakes:

• Using PUT to add new data
• Using POST to update existing data
• Using GET for data changes