24. Application Programming Interfaces (APIs)

BootCamp by Dr.Angela

1. Introduction to APIs

• What is an API?
  • API (Application Programming Interface) acts as a bridge that allows different software applications to communicate with each other.
  • APIs enable programs to exchange data and functionality without exposing internal implementation details.
• REST APIs
  • REST (Representational State Transfer) is a common architectural style for web APIs.
  • REST APIs typically use the HTTP protocol.
• Common HTTP Methods : GET(Retrieve data), POST(Create data), PUT(Replace data), PATCH(Partially update data), DELETE(Remove data)

2. Structuring API Requests

• API Types
  • Private API : Frontend ↔ Your Server, Used internally within your application
  • Public API : Your Server ↔ External Server, Provided by third-party services
• API Documentation : API documentation explains available endpoints, parameters, authentication methods, and response formats.
  • ex) https://bored-api.appbrewery.com/
• API Endpoints : An endpoint is a specific URL that provides access to a resource.
  • Base URL + Endpoint
  • ex) /random, /filter
• Query Parameters : Used to filter, sort, or customize responses.
  • ex) https://bored-api.appbrewery.com/endpoint?query=value&query2=value
  • Format : ?key=value&key2=value2
• Path Parameters : Used to identify a specific resource.
  • ex) https://bored-api.appbrewery.com/endpoint/{id}

3. What is JSON?

• JSON (JavaScript Object Notation) : Lightweight format for storing and exchanging data, Human-readable and language-independent
• JSON vs JavaScript Objects
  • JSON : Stored as text (string) { "name": "John", "age": 25 }
  • JavaScript Object : Actual JavaScript object { name: "John", age: 25 }
• JSON Tools
  • JSON Visualizer : https://jsonviewer.stack.hu/
• Convert JSON to JavaScript Object : const data = JSON.parse(jsonData);
• Convert JavaScript Object to JSON : const jsonData = JSON.stringify(data);

4. Making Server-Side API Requests with Axios

• Axios : Popular HTTP client for JavaScript and Node.js, Simpler syntax than the native https module
• Async/Await : Used to handle asynchronous API requests more cleanly.
  • ex) const response = await axios.get(url);
• Basic GET Request : `import axios from "axios";

const response = await axios.get(url);
console.log(response.data);`

5. API Authentication

• Why Authentication? : Authentication helps control access to APIs and protects resources from unauthorized use.
• Common Authentication Methods
  • No Authentication : Public access, Usually rate-limited
  • Basic Authentication : Username + Password, Credentials are encoded using Base64, Typically sent in HTTP headers
  • API Key Authentication : API Key → API, Unique key issued by the API provider, Often included in headers or query parameters
  • Token-Based Authentication : Username/Password → Token → API, User logs in once, Server returns a token, Future requests use the token
• OAuth : Delegated authorization protocol , Allows users to grant limited access without sharing passwords
  • Commonly used with : Google, GitHub, Facebook

6. REST APIs in Practice

• Making API Requests : GET(Read data), POST(Create data), PUT(Replace data), PATCH(Update part of a resource), DELETE(Remove data)
• CRUD Operations(Operation : HTTP Method)
  • Create : POST
  • Read : GET
  • Update : PUT / PATCH
  • Delete : ELETE
• Axios Examples : https://axios.rest/pages/getting-started/examples/commonjs.html

Axios simplifies server-side API requests.
Authentication methods include Basic Auth, API Keys, Tokens, and OAuth.