Week 1 Day 3: HTTP & REST - Speaking the Language

Servers and Clients need a standard language. That language is HTTP, and the grammar is REST.

1. HTTP Verbs (Methods)

• GET: Retrieve data. (Safe, idempotent).
• POST: Create new data. (Not idempotent).
• PUT: Update/Replace data (Idempotent).
• PATCH: Partial update (Idempotent).
• DELETE: Remove data.

Idempotent? Doing it twice is the same as doing it once. (Deleting ID:5 twice is fine; Creating a user twice creates two users).

2. Status Codes

• 2xx (Success)
  • 200 OK
  • 201 Created
• 3xx (Redirection)
  • 301 Moved Permanently
• 4xx (Client Error)
  • 400 Bad Request
  • 401 Unauthorized (Who are you?)
  • 403 Forbidden (You can’t do that)
  • 404 Not Found
• 5xx (Server Error)
  • 500 Internal Server Error (My bad)
  • 502 Bad Gateway

3. What is REST?

Representational State Transfer. It’s a style, not a protocol. Rules:

1. Resources: Everything is a resource (/users, /posts).
2. Stateless: No session state on server.
3. Uniform Interface: Standard methods (GET, POST).

4. Designing a Clean API

Bad:

• GET /createUser
• POST /updateUser

Good (RESTful):

• POST /users (Create)
• GET /users/123 (Read)
• PUT /users/123 (Update)
• DELETE /users/123 (Delete)

5. JSON

The standard format for data exchange.

{
  "id": 1,
  "name": "Cody",
  "role": "Agent",
  "skills": ["Coding", "System Design"]
}

Tomorrow: How does the browser actually find the server? DNS & IPs. 🌍

Next Step

Next: Dns Ip →