Web API(Application Programming Interface)

A way 2 software communicate with each other over a network.

Protocols

• Network Layer / Thrid Layer

  • IP (Internet Protocol)

• Transport Layer

  • TCP (Transmission Dontrol Protocol)
  • UDP (User Datagram protocol)

• Application Layer

  • HTTP (Hypertext transfer protocol) 80
  • HTTPS (Hypertext transfer protocol secure) 443
  • WS (Websocket) 80
  • WSS (Websocket secure) 443
  • FTP (File Transfer Protocol) 21
  • DNS (Domain Name System) 53

Port

Endpoint to communicate with a software.

DNS(Domain Name System)

Resolves a name to IP address

URL (Uniform Resource Locater)

https://wwww.nodejs.org:443/en/docs?search=api

• https -> Scheme/Protocol
• wwww.nodejs.org -> Domain
  • org -> Top Level Domain (TLD)
  • nodejs -> Main Domain
  • wwww -> Sub Domain
• 443 -> Port
• /en/docs -> Path
  • en -> Folder
  • docs -> Folder
• search=api => URL Parameters / Query

Data Formats / Content-Type

• Text => text/plain
• HTML(Hypertext Markup Language) => text/html
• XML (Extensible Markup Langauge) => application/xml

      <xml>
          <user>
              <name>Bhaktij Koli</name>
              <email>hello@bhaktijkoli.com</email>
          </user>
      </xml>
  

• JSON(JavaScript Object Notation) => application/json

  {
      "name" "Bhaktij Koli",
      "email: "hello@bhaktijkoli.com"
  }
  

• Multimedia (File, Image, etc)

API Architectures

• SOAP (Simple Object Access Protocol)

  • Limited to XML
  • Strict

• REST API(Representational state transfer)

  • XLL, JSON, text, html, images, videos, files

• Websockets

  • Event Driven (Eg: socket.io)
  • Pub/Sub (Eg: IOT)

• RPC(Remote Procedure Call)

  • GRPC(Google Remote Procedure Call)

• GraphQL

  • Apollo
  • Helix
  • Yoga
  • AWS Amplify

RESUT API/RESTFul API

• HTTP Request

  • URL
  • Method
  • Headers
  • Body

• HTTP Response

  • Status Code
  • Headers
  • Body

HTTP Methods

• GET (Fetch Data)(No Request Body)
• POST (Create Data)
• PUT (Update Data by replacing it)
• DELETE (Delete Data)
• PATCH (Update/Repair Data without replacing it)

---

• HEAD (Fetch Headers)(No Response Body)
• CONNECT (Eastablish Connection)(No Request Body)
• OPTIONS (To check for available options)(No Request Body)
• TRACE (Trace)

HTTP Headers

To add additional info or to describe to the request

• Accept
• Authorization
• Content-Type
• Cookie
• Origin
• Custom Headers (start with X)
• X-Powered-By

HTTP Status Codes

• Sucessful Response
  • 200 (OK)
• Redirect Response
  • 301
• Client Error Response
  • 400 (Bad Request)
  • 401 (Not Authenticated)
  • 403 (Forbiden)
  • 404 (Not Found)
  • 405 (Not Authorized)
• Server Error Response
  • 500 (Internal Server Error)

Learn More

Cookie

- Maintain client side

Session

- Maitain server side

CORS (Cross Origin Resource Sharing)

Access-Control-Allow-Origin: '*' Access-Control-Allow-Methods: 'GET,POST', Access-Control-Allow-Headers: