# Activity 30: HTTP Status Codes

In RESTful APIs, HTTP status codes are essential for indicating the result of a request. Here’s an overview of the main categories of HTTP status codes and their common uses:

### 1xx: Informational

These codes let the client know that the request was received and is still being processed:

* **100 Continue**: Indicates that the initial part of the request was accepted, and the client can continue sending the rest.
    
* ```http
    HTTP/1.1 100 Continue
    ```
    
* **101 Switching Protocols**: Confirms a protocol change requested by the client.
    

```http
HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
```

### 2xx: Success

These codes mean the request was successfully received and processed:

* **200 OK**: The request was successful, and the server is returning the requested data.
    

```http
GET /users/123 HTTP/1.1
Host: api.example.com

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

{
  "id": 123,
  "name": "Jane Doe",
  "email": "jane@example.com"
}
```

* **201 Created**: A new resource was successfully created, often returned for `POST` requests.
    

```http
POST /users HTTP/1.1
Host: api.example.com
Content-Type: application/json

{
  "name": "John Doe",
  "email": "john@example.com"
}

HTTP/1.1 201 Created
Location: /users/124
Content-Type: application/json

{
  "id": 124,
  "name": "John Doe",
  "email": "john@example.com"
}
```

* **204 No Content**: The server processed the request successfully but has no content to return (common for `DELETE` requests).
    

```http
DELETE /users/123 HTTP/1.1
Host: api.example.com

HTTP/1.1 204 No Content
```

### 3xx: Redirection

Redirection codes indicate the client needs to perform further actions to complete the request:

* **301 Moved Permanently**: The resource has a new permanent URL, and future requests should use this new URL.
    

```http
GET /old-path HTTP/1.1
Host: api.example.com

HTTP/1.1 301 Moved Permanently
Location: /new-path
```

* **302 Found**: The resource temporarily resides at a different URL, and future requests should continue to use the original URL.
    

```http
HTTP/1.1 302 Found
Location: https://www.example.com/temporary-page
```

* **307 Temporary Redirect**: Similar to 302, but the client should resubmit the request to the new URL.
    

```http
POST /submit HTTP/1.1
Host: api.example.com

HTTP/1.1 307 Temporary Redirect
Location: https://api.example.com/temp-submit
```

### 4xx: Client Errors

Client error codes indicate a problem with the request from the client:

* **400 Bad Request**: The server couldn’t understand the request due to invalid syntax.
    

```http
POST /users HTTP/1.1
Host: api.example.com
Content-Type: application/json

{
  "name": "Jane" "email": "jane@example.com" // Missing comma

HTTP/1.1 400 Bad Request
Content-Type: application/json

{
  "error": "Invalid JSON format"
}
```

* **401 Unauthorized**: Authentication is required, but it was not provided or is invalid.
    

```http
GET /users/123 HTTP/1.1
Host: api.example.com

HTTP/1.1 401 Unauthorized
Content-Type: application/json

{
  "error": "Authentication required"
}
```

* **403 Forbidden**: The client is authenticated but doesn’t have permission to access the resource.
    

```http
GET /admin HTTP/1.1
Host: api.example.com

HTTP/1.1 403 Forbidden
Content-Type: application/json

{
  "error": "You do not have permission to access this resource"
}
```

* **404 Not Found**: The server can’t find the requested resource.
    

```http
GET /users/999 HTTP/1.1
Host: api.example.com

HTTP/1.1 404 Not Found
Content-Type: application/json

{
  "error": "User not found"
}
```

* **429 Too Many Requests**: The client has sent too many requests in a short period, triggering rate limiting.
    

```http
HTTP/1.1 429 Too Many Requests
Content-Type: application/json
Retry-After: 60

{
  "error": "Too many requests",
  "message": "You have exceeded the rate limit. Please wait 60 seconds before trying again."
}
```

### 5xx: Server Errors

These codes mean the server encountered an error while processing the request:

* **500 Internal Server Error**: A general error when the server encounters an unexpected issue.
    

```http
GET /users HTTP/1.1
Host: api.example.com

HTTP/1.1 500 Internal Server Error
Content-Type: application/json

{
  "error": "An unexpected error occurred. Please try again later."
}
```

* **502 Bad Gateway**: A server acting as a gateway received an invalid response from an upstream server.
    

```http
HTTP/1.1 502 Bad Gateway
Content-Type: application/json

{
  "error": "Bad Gateway",
  "message": "The server received an invalid response from the upstream server."
}
```

* **503 Service Unavailable**: The server is temporarily unable to handle the request, often due to maintenance or overload.
    

```http
GET /users HTTP/1.1
Host: api.example.com

HTTP/1.1 503 Service Unavailable
Content-Type: application/json

{
  "error": "Service is temporarily unavailable. Please try again later."
}
```

* **504 Gateway Timeout**: A server acting as a gateway did not receive a timely response from an upstream server.
    

```http
HTTP/1.1 504 Gateway Timeout
Content-Type: application/json

{
  "error": "Gateway Timeout",
  "message": "The server did not receive a timely response from the upstream server."
}
```

Each status code provides specific information to clients and is fundamental in REST API design, where they help manage client-server interactions effectively. Understanding and using the appropriate status codes will enhance the client experience by providing clear feedback on the request status