APIs and networking allow applications to:

• Communicate with each other
• Exchange data
• Connect over networks

Python provides powerful libraries for:

• REST APIs
• HTTP requests
• JSON handling
• Authentication
• Socket programming

---

What is an API?

API stands for:

Application Programming Interface

An API allows software applications to communicate.

Examples:

• Weather apps
• Payment gateways
• Social media integrations

---

REST APIs

REST stands for:

Representational State Transfer

REST APIs use HTTP methods:

Method	Purpose
GET	Retrieve data
POST	Create data
PUT	Update data
DELETE	Remove data

---

Example API URL

https://api.example.com/users

---

Using requests Library

The requests library is used to send HTTP requests.

---

Install Requests

pip install requests

---

Import Requests

import requests

---

GET Request

Used to fetch data.

import requests

response = requests.get(
    "https://api.github.com"
)

print(response.status_code)
print(response.text)

---

Response Status Codes

Code	Meaning
200	Success
404	Not found
500	Server error
401	Unauthorized

---

JSON Response

Most APIs return JSON data.

data = response.json()

print(data)

---

POST Request

Used to send data.

import requests

data = {
    "name": "Aditya",
    "course": "Python"
}

response = requests.post(
    "https://httpbin.org/post",
    json=data
)

print(response.json())

---

PUT Request

Used to update data.

data = {
    "name": "Updated Name"
}

response = requests.put(
    "https://httpbin.org/put",
    json=data
)

print(response.status_code)

---

DELETE Request

Used to remove data.

response = requests.delete(
    "https://httpbin.org/delete"
)

print(response.status_code)

---

Request Headers

Headers provide additional information.

headers = {
    "User-Agent": "Python App"
}

response = requests.get(
    "https://api.github.com",
    headers=headers
)

---

Query Parameters

params = {
    "page": 1,
    "limit": 5
}

response = requests.get(
    "https://httpbin.org/get",
    params=params
)

print(response.url)

---

JSON Handling

JSON stands for:

JavaScript Object Notation

Used for storing and exchanging data.

---

Python Dictionary to JSON

import json

data = {
    "name": "Aditya",
    "age": 25
}

json_data = json.dumps(data)

print(json_data)

---

JSON to Python Dictionary

import json

text = '{"name":"Aditya"}'

data = json.loads(text)

print(data)

---

Read JSON File

import json

with open("data.json", "r") as file:

    data = json.load(file)

print(data)

---

Write JSON File

import json

data = {
    "course": "Python"
}

with open("data.json", "w") as file:

    json.dump(data, file, indent=4)

---

API Authentication

Many APIs require authentication for security.

Common authentication methods:

• API Keys
• Tokens
• OAuth

---

API Key Authentication

headers = {
    "Authorization": "Bearer YOUR_API_KEY"
}

response = requests.get(
    "https://api.example.com/data",
    headers=headers
)

---

Token Authentication Example

token = "your_token"

headers = {
    "Authorization": f"Bearer {token}"
}

response = requests.get(
    "https://api.example.com/profile",
    headers=headers
)

---

Basic Authentication

from requests.auth import HTTPBasicAuth

response = requests.get(
    "https://api.example.com",
    auth=HTTPBasicAuth(
        "username",
        "password"
    )
)

---

Handling API Errors

import requests

try:

    response = requests.get(
        "https://api.github.com"
    )

    response.raise_for_status()

    print(response.json())

except requests.exceptions.RequestException as e:
    print("Error:", e)

---

Socket Programming Basics

Socket programming enables communication between devices over a network.

Used for:

• Chat applications
• Multiplayer games
• Real-time systems

Python provides:

socket

module.

---

Import Socket Module

import socket

---

Socket Server Example

import socket

server = socket.socket()

server.bind(("localhost", 12345))

server.listen(1)

print("Waiting for connection...")

client, address = server.accept()

print("Connected:", address)

client.send(
    "Hello Client".encode()
)

client.close()

---

Socket Client Example

import socket

client = socket.socket()

client.connect(("localhost", 12345))

message = client.recv(1024)

print(message.decode())

client.close()

---

UDP Socket Example

import socket

sock = socket.socket(
    socket.AF_INET,
    socket.SOCK_DGRAM
)

sock.sendto(
    b"Hello",
    ("localhost", 12345)
)

---

Practical Example

Weather API Example

import requests

url = "https://api.openweathermap.org/data/2.5/weather"

params = {
    "q": "Delhi",
    "appid": "YOUR_API_KEY"
}

response = requests.get(
    url,
    params=params
)

data = response.json()

print(data)

---

Advantages of APIs

✅ Easy data exchange
✅ Connect multiple applications
✅ Automation support
✅ Real-time communication
✅ Scalable integration

---

Best Practices

✅ Secure API keys
✅ Handle API errors properly
✅ Use HTTPS APIs
✅ Validate JSON responses
✅ Avoid excessive API requests

---

Summary

In this chapter you learned:

✅ REST APIs
✅ Using requests
✅ JSON handling
✅ API authentication
✅ Socket programming basics