REST API for IoT device in Raspberry Pi - Step-by-Step Execution

Concept Flow - REST API for IoT device

Start Raspberry Pi

↓

Initialize REST API Server

↓

Wait for HTTP Request

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Receive Request

↓

Parse Request Type

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Read Sensor

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Send Response

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Wait for Next Request

The Raspberry Pi starts a REST API server that waits for HTTP requests. It handles GET requests by reading sensors and POST requests by updating device settings, then sends responses.

Execution Sample

Raspberry Pi

from flask import Flask, request, jsonify
app = Flask(__name__)

@app.route('/sensor', methods=['GET'])
def get_sensor():
    return jsonify({'temperature': 22})

@app.route('/device', methods=['POST'])
def update_device():
    data = request.get_json()
    # Here you would update device settings based on data
    return jsonify({'status': 'updated'})

This code creates a simple REST API on Raspberry Pi that returns a temperature reading when '/sensor' is requested with GET and updates device settings when '/device' is requested with POST.

Execution Table

Step	Action	Request Type	Internal Process	Response Sent
1	Start server	None	Initialize Flask app	None
2	Wait for request	None	Idle, listening	None
3	Receive request	GET /sensor	Call get_sensor function	None
4	Process request	GET /sensor	Read temperature sensor (simulated 22)	None
5	Send response	GET /sensor	Return JSON {'temperature': 22}	{'temperature': 22}
6	Wait for next request	None	Idle, listening	None
7	Receive request	POST /device	Parse JSON payload	None
8	Process request	POST /device	Update device settings	None
9	Send response	POST /device	Return success message	{'status': 'updated'}
10	Wait for next request	None	Idle, listening	None

💡 Server runs continuously, stops only on manual shutdown.

Variable Tracker

Variable	Start	After Step 4	After Step 8	Final
temperature	None	22	22	22
device_settings	Default	Default	Updated	Updated
response	None	{'temperature': 22}	{'temperature': 22}	{'status': 'updated'}

Key Moments - 3 Insights

Why does the server wait after sending a response?

The server waits to listen for new requests, as shown in steps 2, 6, and 10 in the execution_table. It keeps running to handle multiple requests.

How does the server know which function to run for a request?

The server matches the request path and method (like GET /sensor) to the correct function, as in step 3 where GET /sensor calls get_sensor.

What happens if a POST request updates device settings?

In steps 7-9, the server parses the POST data, updates device_settings variable, and sends a confirmation response.

Visual Quiz - 3 Questions

Look at the execution_table, what is the response sent at step 5?

A No response sent

B {'status': 'updated'}

C {'temperature': 22}

D Error message

💡 Hint

Check the 'Response Sent' column at step 5 in the execution_table.

At which step does the device_settings variable change?

A Step 4

B Step 8

C Step 3

D Step 10

💡 Hint

Look at variable_tracker for device_settings changes and match with execution_table steps.

If the server stopped waiting after sending a response, what would happen?

A It would shut down and stop responding to new requests

B It would handle multiple requests normally

C It would send multiple responses for one request

D It would crash immediately

💡 Hint

Refer to key_moments about server waiting after responses and execution_table steps 2, 6, 10.

Concept Snapshot

REST API on Raspberry Pi:
- Start server and listen for HTTP requests
- GET requests read sensor data and return JSON
- POST requests update device settings
- Server waits after each response to handle more requests
- Use Flask or similar Python library for implementation

Full Transcript

This visual execution shows how a Raspberry Pi runs a REST API server for an IoT device. The server starts and waits for HTTP requests. When it receives a GET request at '/sensor', it reads the temperature sensor (simulated as 22) and sends back a JSON response. For POST requests to '/device', it updates device settings and confirms with a JSON message. The server waits after each response to handle more requests, running continuously until manually stopped. Variables like temperature and device_settings change as requests are processed. This step-by-step trace helps beginners see how REST APIs work on IoT devices.