1. Skills: none Concepts: Web client (browser), Web server, network connection, URL, mobile client, protocol This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 License. Retrieving a Web page

2. Where does this topic fit? Internet concepts – Applications – Technology – Implications Internet skills – Application development – Content creation – User skills

3. The World Wide Web in plain English (2m 46s): http://www.commoncraft.com/world-wide-web Watch this video

4. Client and server Client Server Can you name a Web client program? If not, ask someone to explain this question to you.

5. What happens next? Uniform resource locator (URL)

6. Establish a temporary connection Client Server

7. Request the page Client Server Request

8. Send the page to the client Client Server Request page

9. Client displays the page Client Server Request

10. page Drop the connection Client Server Request

11. Data flow Web server program Memory Storage Requested page Web client program Memory Display Requested page ClientServer Request Page The Internet

12. What if the requested page is not found? What does the “page not found” error message at www.google.com look like?www.google.com

13. Pages with links Client Server 1 Server 2 1. Get first page 2. Get second page

14. Mobile Web clients

15. 1. Establish a temporary connection between the client and server 2. Client sends the request to the server 3. Server returns the requested page or an error message 4. Client displays whatever the server returns 5. Disconnect – drop the connection Client Server request page Summary: retrieving a Web page

16. 1.What happens if the user accidentally misspells the URL? 2.Can a server be handling requests from more than one client at a time? Answer yes or no then explain your answer. 3.If a Web page contains a link to another page, must both pages be stored on the same server? Answer yes or no then explain your answer. 4.If a Web page contains a link to another page, may both pages be stored on the same server? Answer yes or no then explain your answer. 5.Do the terms client and server refer to hardware, software or both? Explain your answer. 6.At least two programs must be in your computer’s memory while you are surfing the Web – which programs? 7.What is in memory beside those programs while you are looking at a Web page on the screen? Self-study questions

17. 1. 2. 3. 4. 5. Client Server request page Without looking back, do you recall the steps in retrieving a Web page?