Notes

HTTP Requests and Responses

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HTTP communications mainly consist of an HTTP requests and responses. A request is made by the client i.e. either the browser or curl and is processed by the server and is bundled in a response back to the user.

HTTP Request

  1. Request Line:
    • Fields: Separated by spaces:
      • Method: Specifies the action (e.g., GET, POST).
      • Path: Target resource path (e.g., /users/login.html).
      • Version: HTTP version (e.g., HTTP/1.1).
  2. Headers: Key-value pairs providing metadata (e.g., Host, User-Agent).
  3. Body (Optional): Contains data like POST (e.g., form data or JSON).
GET /users/login.html HTTP/1.1
Host: inlanefreight.com
User-Agent: curl/7.65.3
Accept: */*

HTTP Response

  1. Response Line:
    • HTTP Version: (e.g., HTTP/1.1).
    • Response Code: Status of the request (e.g., 200 OK, 401 Unauthorized).
  2. Headers: Metadata about the response (e.g., Content-Length, Content-Type).
  3. Body: Contains the requested data or error message (e.g., HTML, JSON).
HTTP/1.1 401 Unauthorized
Content-Length: 464
Content-Type: text/html; charset=iso-8859-1

Tools for Examining HTTP Communications

  1. curl: A command-line tool to send and inspect HTTP requests.
curl http://example.com
curl -v http://example.com
curl --help or man curl
  1. Browser DevTools: Built-in tools in modern browsers (Chrome, Firefox) to inspect web interactions.
  • Opening DevTools: Press CTRL+SHIFT+I or F12.
  • Network Tab:
    • Displays all HTTP requests and responses.
    • Shows response status, method, URL, and headers.
    • Filter and search requests for easier debugging.
    • Use Network Log for tracing web application performance.

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