Bird
Raised Fist0
IOT Protocolsdevops~6 mins

HTTP request methods for IoT (GET, POST, PUT) in IOT Protocols - Full Explanation

Choose your learning style10 modes available
LearnWhyDeepVisualTryChallengeProjectRecallTime
Introduction
Imagine you want to control or get information from a smart device like a thermostat or a light bulb. To do this, your device and the controller need a way to talk and share data clearly. HTTP request methods help devices send and receive information in a simple, organized way.
Explanation
GET Method
The GET method asks a device for information without changing anything. It is like asking a question and waiting for an answer. For example, a smart thermostat can send a GET request to check the current temperature. This method is safe because it only reads data and does not modify the device.
GET requests retrieve data from a device without making any changes.
POST Method
The POST method sends new data to a device to create or update something. It is like giving instructions or sending a message that changes the device's state. For example, turning on a smart light bulb or sending sensor data to a server uses POST. This method can change the device or add new information.
POST requests send data to a device to create or update information.
PUT Method
The PUT method replaces existing data on a device with new data. It is like updating a file completely with fresh content. For example, changing the settings of a smart thermostat to a new temperature uses PUT. This method ensures the device's data matches exactly what was sent.
PUT requests update or replace existing data on a device.
Real World Analogy

Think of a smart home where you can ask your assistant about the weather, send a message to turn on the lights, or update the thermostat settings. Each action uses a different way of communicating to get information, send commands, or change settings.

GET Method → Asking your assistant, 'What's the temperature?' and waiting for the answer.
POST Method → Telling your assistant, 'Turn on the living room lights' to change the state.
PUT Method → Saying, 'Set the thermostat to 22 degrees' to update the settings exactly.
Diagram
Diagram
┌─────────────┐       GET        ┌─────────────┐
│ Controller  │ ───────────────▶ │ IoT Device  │
└─────────────┘                  └─────────────┘
       ▲                             │
       │                             │
       │          POST               │
       │ ─────────────────────────▶ │
       │                             │
       │                             ▼
┌─────────────┐       PUT        ┌─────────────┐
│ Controller  │ ───────────────▶ │ IoT Device  │
└─────────────┘                  └─────────────┘
Diagram showing how the controller sends GET, POST, and PUT requests to an IoT device.
Key Facts
GET → Retrieves data from an IoT device without changing it.
POST → Sends new data or commands to an IoT device to create or update.
PUT → Replaces existing data on an IoT device with new data.
Idempotent → PUT requests are idempotent, meaning repeating them has the same effect as doing it once.
Safe Method → GET is considered safe because it does not modify data.
Common Confusions
GET requests can change device settings.
GET requests can change device settings. GET requests only retrieve data and do not modify any device settings or state.
POST and PUT are the same because both send data.
POST and PUT are the same because both send data. POST creates or adds new data, while PUT replaces existing data completely.
Summary
GET requests ask IoT devices for information without changing anything.
POST requests send new data or commands to create or update device state.
PUT requests replace existing data on devices with new data exactly.

Practice

(1/5)
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
Recommended

Ready to prove it?

Pass the test and this pattern moves unknown strong while earning +1 Grip toward your certificate.

10 questions~5 mineasy hard