Learning Objectives

After successfully completing this section, you should be able to

  1. explain Hypertext Transfer Protocol (HTTP).
  2. explain how HTTP is related to the World Wide Web, to Web servers, and to Web browsers.
  3. outline the communications between a Web server and a Web browser.

Learning Tasks

Required:

  1. Watch the slideshow for this section
  2. Study Section 2.2, The Web and HTTP, in the textbook.

Terms and Topics

Section 2 – Network Application—HTTP and the World Wide Web

Web page
Web object
Base HTML file
Web browsers
Web servers
Stateless protocol
Non-persistent connection
Persistent connection
Round-trip time (RTT)
HTTP/1.1
HTTP/2
HTTP message format
HTTP Request message
Request line
Header lines (of request message)

General format of HTTP request message
Entity body (HTTP request message)
HTTP response message
Status line
Header lines (of response message)
Entity body (HTTP response message)
General format of HTTP response message
Cookies for user-server interaction
Web caching and Web caches
Proxy server
Conditional GET

Leading Questions

  1. What is HTTP? What does it define? What transport protocol does TCP use, and why?
  2. What is the relationship between HTTP and the World Wide Web?
  3. What is a Web page? Describe HTML and the function of an HTML file. How is an HTML file made?
  4. What are the differences between HTTP/1.1 and HTTP/2?
  5. What is a URL? Provide examples.
  6. What is a Web browser? What are the most popular browsers used today?
  7. What is a Web server? What Web server software systems are the most popular?
  8. How does TCP avoid network congestion?
  9. What is slow start?
  10. Why is HTTP called a stateless protocol?
  11. What are non-persistent connections? What are persistent connections? What is the default connection for HTTP/1.1?
  12. How is round-trip time (RTT) defined?
  13. What are the shortcomings of non-persistent connections?
  14. What are the disadvantages of a persistent connection without pipelining?
  15. In what format are HTTP request messages sent from a user agent such as a Web browser?
  16. What are request lines?
  17. What are header lines?
  18. What methods can be used by HTTP to send objects?
  19. What are the differences between the Get and Post methods?
  20. In what format are HTTP response messages sent from an HTTP server?
  21. What is authentication? How can a user be authenticated on the Web?
  22. What are cookies and what are they used for?
  23. What is Web caching? Why is Web caching used? Where can a Web cache reside?
  24. What is the conditional GET? How does it work? What are the advantages?
  25. Why might cooperative caching be more useful?