Why web servers enable remote IoT control in Raspberry Pi - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start a simple web server on the Raspberry Pi.

Raspberry Pi

from http.server import HTTPServer, SimpleHTTPRequestHandler

server = HTTPServer(('0.0.0.0', [1]), SimpleHTTPRequestHandler)
server.serve_forever()

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

A443

B3306

C22

D8080

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing port 22 which is for SSH, not HTTP.

The port 8080 is commonly used for web servers on Raspberry Pi for testing and remote control.

2fill in blank

medium

Complete the code to handle a GET request and respond with a message.

Raspberry Pi

from http.server import BaseHTTPRequestHandler

class Handler(BaseHTTPRequestHandler):
    def do_GET(self):
        self.send_response(200)
        self.send_header('Content-type', 'text/plain')
        self.end_headers()
        self.wfile.write(b'[1]')

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

AHello, IoT!

BError 404

CUnauthorized

DServer busy

Attempts:

3 left

💡 Hint

Common Mistakes

Using error messages instead of a success message.

The server should respond with a friendly message like 'Hello, IoT!' to confirm it is working.

3fill in blank

hard

Fix the error in the code to correctly parse the URL path for IoT commands.

Raspberry Pi

from urllib.parse import urlparse

path = urlparse(self.path).[1]
if path == '/led/on':
    self.wfile.write(b'LED turned on')

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

Aquery

Bpath

Cparams

Dnetloc

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'query' or 'params' instead of 'path'.

The 'path' attribute of the parsed URL gives the URL path to check commands like '/led/on'.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps device names to their status if status is 'on'.

Raspberry Pi

devices = {'lamp': 'on', 'fan': 'off', 'heater': 'on'}
on_devices = { [1] : [2] for [1] in devices if devices[[1]] == 'on' }

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

Adevice

Bdevices[device]

Cstatus

Ddevice_status

Attempts:

3 left

💡 Hint

Common Mistakes

Using undefined variable names or wrong dictionary keys.

The comprehension uses 'device' as the key and 'devices[device]' as the value for devices that are 'on'.

5fill in blank

hard

Fill all three blanks to create a function that turns on a device and returns a confirmation message.

Raspberry Pi

def control_device([1]):
    devices[[2]] = 'on'
    return f"[3] turned on"

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

Adevice_name

Dstatus

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names causing errors.

The function takes 'device_name' as input, sets its status to 'on', and returns a message using the same variable.

Practice

1. Why do web servers enable remote control of IoT devices like Raspberry Pi?
Web servers provide a way to access devices over the internet.

easy

A. They store all device data locally without internet access.

B. They make devices run faster by upgrading hardware automatically.

C. They prevent devices from connecting to the internet.

D. They allow users to send commands to devices from anywhere using a web browser.

Solution

1. Step 1: Understand the role of web servers in IoT

   Web servers host web pages and APIs that users can access remotely via the internet.

2. Step 2: Connect remote access to device control

   By accessing the web server on the Raspberry Pi, users can send commands to control IoT devices from anywhere.

3. Final Answer:

   They allow users to send commands to devices from anywhere using a web browser. -> Option D

4. Quick Check:

   Remote control = Web server access [OK]

Hint: Web servers let you control devices via internet browsers [OK]

Common Mistakes:

• Thinking web servers upgrade hardware
• Believing data is stored only locally
• Assuming web servers block internet access

2. Which of the following is the correct way to start a simple web server on a Raspberry Pi using Python?

import http.server
import socketserver

PORT = 8000
Handler = http.server.SimpleHTTPRequestHandler

with socketserver.TCPServer(("", PORT), Handler) as httpd:
    httpd._____()

easy

A. serve_forever

B. listen

C. start_server

D. run

Solution

1. Step 1: Identify the method to keep the server running

   The method serve_forever() keeps the server active and listening for requests.

2. Step 2: Match the method name in the code

   The code uses httpd._____(), so the correct method to fill is serve_forever.

3. Final Answer:

   serve_forever -> Option A

4. Quick Check:

   Keep server running = serve_forever() [OK]

Hint: Remember Python server uses serve_forever() to run [OK]

Common Mistakes:

• Using run() which does not exist
• Using start_server() which is not a method
• Using listen() which is for sockets, not HTTPServer

3. What will be the output when accessing the Raspberry Pi web server URL if the server code includes:

from http.server import SimpleHTTPRequestHandler
from socketserver import TCPServer

PORT = 8080

with TCPServer(("", PORT), SimpleHTTPRequestHandler) as httpd:
    print(f"Serving at port {PORT}")
    httpd.handle_request()

and a user visits http://raspberrypi.local:8080/?

medium

A. Server handles one request and then stops

B. Server runs forever and serves multiple requests

C. Serving at port 8080

D. SyntaxError due to missing parentheses

Solution

1. Step 1: Understand the use of handle_request()

   The method handle_request() processes only one HTTP request and then stops.

2. Step 2: Analyze the code behavior on user access

   When the user visits the URL, the server will serve that single request and then stop running.

3. Final Answer:

   Server handles one request and then stops -> Option A

4. Quick Check:

   handle_request() = single request served [OK]

Hint: handle_request() serves one request only [OK]

Common Mistakes:

• Confusing handle_request() with serve_forever()
• Expecting server to run continuously
• Thinking print output is the server response

4. Identify the error in this Raspberry Pi web server code snippet:

import http.server
import socketserver

PORT = 8000
Handler = http.server.SimpleHTTPRequestHandler

with socketserver.TCPServer(("localhost", PORT), Handler) as httpd:
    httpd.serve_forever

medium

A. Incorrect import of http.server module

B. Missing parentheses after serve_forever method call

C. PORT number must be above 9000

D. Handler should be a function, not a class

Solution

1. Step 1: Check method call syntax

   The method serve_forever must be called with parentheses () to execute.

2. Step 2: Identify the missing parentheses

   The code uses httpd.serve_forever without (), so the server will not start.

3. Final Answer:

   Missing parentheses after serve_forever method call -> Option B

4. Quick Check:

   Method call needs () = Missing parentheses [OK]

Hint: Method calls need () to run in Python [OK]

Common Mistakes:

• Forgetting parentheses on method calls
• Thinking port number limits cause errors here
• Confusing class and function usage

5. You want to control an LED connected to your Raspberry Pi remotely using a web server. Which approach best explains why running a web server on the Pi enables this?

# Pseudocode
Start web server
When user visits URL:
  Receive command (e.g., turn LED on/off)
  Execute GPIO control based on command
  Send response back to user

hard

A. The web server stores LED status but cannot control hardware.

B. The web server automatically powers the LED without commands.

C. The web server listens for internet requests and triggers hardware actions accordingly.

D. The web server only works if the Pi is offline.

Solution

1. Step 1: Understand web server role in IoT control

   The web server listens for commands sent via internet requests from users.

2. Step 2: Connect commands to hardware control

   When a command is received, the server runs code to control the GPIO pins, turning the LED on or off.

3. Final Answer:

   The web server listens for internet requests and triggers hardware actions accordingly. -> Option C

4. Quick Check:

   Web server + commands = hardware control [OK]

Hint: Web server receives commands to control hardware remotely [OK]

Common Mistakes:

• Thinking server powers hardware automatically
• Believing server only stores data without control
• Assuming server works offline for remote control