Introduction

In this tutorial, we will explore what HTTP methods and status codes are, along with their usage within RESTful APIs. By the end of this tutorial, you will understand the purpose of various HTTP methods and status codes, and how to correctly use them.

You will learn:
- What HTTP methods and status codes are
- The purpose of different HTTP methods
- How to interpret HTTP status codes

Prerequisites:
- Basic knowledge of web development
- Familiarity with RESTful APIs

Step-by-Step Guide

HTTP Methods

HTTP methods, also known as HTTP verbs, indicate the desired action to be performed on a given resource. Here are some of the most commonly used HTTP methods:

• GET: Retrieves information about a resource.
• POST: Sends data to a server to create a new resource.
• PUT: Updates an existing resource with new data.
• DELETE: Deletes a resource.

HTTP Status Codes

HTTP status codes are three-digit responses that a server returns after processing a client's request. They indicate whether a request was successful, and if not, why.

There are five classes of HTTP status codes:
- 1xx (Informational): Request received, continuing process.
- 2xx (Successful): Request received, understood, and accepted.
- 3xx (Redirection): Further action must be taken to complete the request.
- 4xx (Client Error): The request contains bad syntax or cannot be fulfilled.
- 5xx (Server Error): The server failed to fulfill a valid request.

Code Examples

Example 1: GET Method

GET /articles HTTP/1.1
Host: www.example.com

This example sends a GET request to retrieve all articles from the server at www.example.com.

Example 2: POST Method

POST /articles HTTP/1.1
Host: www.example.com
Content-Type: application/json

{
  "title": "New Article",
  "content": "This is a new article."
}

This example sends a POST request to create a new article on the server.

Example 3: HTTP Status Code 200 (OK)

HTTP/1.1 200 OK
Content-Type: application/json

[
  {
    "id": 1,
    "title": "Existing Article",
    "content": "This is an existing article."
  }
]

This example shows a server responding with a status code of 200, indicating that the request was successful.

Summary

In this tutorial, we have covered the basic HTTP methods and status codes, their purposes, and how to use them in API requests and responses. Next, you may want to learn about more advanced topics like HTTP headers and cookies.

Practice Exercises

1. Exercise 1: Make a POST request to create a new resource. What status code should the server return if the operation is successful?
2. Exercise 2: Your client makes a GET request to a non-existent resource. What status code should the server return?
3. Exercise 3: Your client makes a DELETE request to a resource. However, the server encounters an error and can't fulfill the request. What status code should the server return?

Solutions:

1. The server should return a 201 (Created) status code.
2. The server should return a 404 (Not Found) status code.
3. The server should return a 500 (Internal Server Error) status code.

Remember, the key to mastering HTTP methods and status codes is practice. Keep exploring different scenarios and how these concepts apply to them.