PHP 5 Unleashed

Appendix B. HTTP Reference

IN THIS APPENDIX

• What Is HTTP?

• PHP Programming Libraries for HTTP Work

• Understanding an HTTP Transaction

• HTTP Client Methods

• What Comes Back: Server Response Codes

• HTTP Headers

• Encoding

• Identifying Clients and Servers

• The “Referer”

• Fetching Content from an HTTP Source

• Media Types

• Cookies: Preserving State and a Tasty Treat

• Security and Authorization

• Client-Side Caching of HTTP Content

In this appendix we'll discuss the HTTP standard from the perspective of a PHP programmer, with a look at the functions and libraries you might use.

What Is HTTP?

HTTP is to Web pages what FTP is to file access. It is the core protocol behind the World Wide Web. Every click on a Web page, every image that is displayed, every style sheet that is requested ...