What You'll Be Learning About Today

• Definition of the World Wide Web
• Uniform Resource Locators
• Netscape Basics
• Some WWW Exercises
• Tips and Tricks for Using the WWW
• More Topics for This Week

• The World Wide Web or WWW or "The Web": A global collection of documents (called pages) linked together using hypertext.
• Hypertext: Documents that are read by following links of interest to similar topics - as opposed to reading straight through a document from beginning to end.
  • Normally we read a book in a linear fashion. Page 1, then Page 2, etc.
  • With hypertext, we follow our curiosity by skipping around the document(s) using hypertext links.
  Hypertext is made up of three distinct parts:
  1. Text Pages - The text you read.
  2. Anchors - The starting point for a link.
  3. Links - A pointer to another text page.

• WWW Pages are stored on Internet hosts.
• Pages are accessed using a WWW Browser such as Netscape, Mosaic or Microsoft's Internet Explorer.
• Pages can contain text and graphics to be viewed.
• Pages can also contain movies, sounds or animations to be downloaded and viewed.
• Pages are written in the HyperText Markup Language (HTML) - more on this later.
• The address or location of a WWW page is defined by its Uniform Resource Locator or URL.

• URL: A three part name for a WWW or Internet resource:

      protocol://hostname/filename
  

  1. Protocol: The method used to access the resource. Examples:

           http     ftp     gopher     mailto
     

  2. Host Name: The name of the host where the resource is located.
  3. File Name: The directory and file name of the resource.
• In most cases, the method used to access resources (protocol) will be http.
• HTTP: the HyperText Transfer Protocol.

URL Examples

1. http://pegasus.rutgers.edu/~holowcza/index.html
         

   HTTP Protocol. Host name is pegasus.rutgers.edu and file is ~holowcza/index.html
   

2. ftp://ftp.std.com/obi/William.Butler.Yeats/Yeats/Balloon
         

   FTP Protocol. Host name is ftp.std.com and the file is obi/William.Butler.Yeats/Yeats/Balloon
   

3. gopher://stis.nsf.gov
              

   Gopher Protocol. Host name is stis.nsf.gov and the root Gopher menu will be shown.

• Notice: All lower case letters with no spaces.

• Netscape Navigator is a WWW Browser from the Netscape Corp.
• We have version 2.02 installed in the Rutgers Labs.
• Netscape runs in MS Windows so we'll be using the mouse quite a bit.
• We will practice with some of the example sites shown above.

Netscape Functions

• Find out how much money it costs to go on a tour of the White House in Washington, D.C.
  1. Pull down the File menu and choose the Open Location menu choice.
  2. Type in the URL for the White House:
     http://www.whitehouse.gov
  3. Press Enter and the White House home page will appear. This might take a minute since we are all accessing the page at the same time.
  4. Scroll down until you see "White House History and Tours"
  5. Click on the icon next to the text there. The White House History and Tours Web page will appear.
  6. Scroll down until you see the text: "If you are coming for a visit, please read this information on White House Tours"
  7. Click on the underlined text. The White House Tour Information Web page will appear.
  8. Scroll down to the first paragraph...

Try the following tasks on your own

• Go to the NASA WWW site and find out when the next shuttle launch is scheduled.
• Go to Rich's WWW home page and find out where he attended college as an undergraduate (Hint: It wasn't Rutgers :)
• Go to the Library of Congress home page and find out what Thomas is and what information Thomas contains.

• A Common Netscape Error message is: Netscape is unable to locate the server: xyz.com Check the server name in the location and try again. One of the following might be the problem:
  1. The host name is misspelled. Check your spelling and try again. Make sure you use lower case letters.
  2. The host is currently not running. Try again at a later time.
  3. The host has been shut down or the site has been moved. Not much you can do.
• Another common Error message: 404 - Not Found In this case, the host is running but it could not find the file you specified. Check the URL and try it again.
• In many cases, these error messages appear because a host changes its configuration such as its name or the location of its files.
• Some things to try:
  1. Try going to the main home page directly. For example, if this URL does not work: http://cimic3.rutgers.edu/music/rich/notes.html Give one of the following a try instead: http://cimic3.rutgers.edu/music/rich/ http://cimic3.rutgers.edu/music/ http://cimic3.rutgers.edu/
• Sometimes you will come across a site that is running very slowly. Very popular Web sites can be bogged down with many requests for pages. Here are some tips:
  1. If the Web page has a lot of images (pictures), it will load very slowly. Try going to the Netscape Options menu and un-checking the Auto Load Images option. This will prevent images from being loaded into your browser. The result may be ugly, but the page will load much faster.
  2. If, while loading a web page, the browser seems to freeze - that is, the netscape logo is doing its thing but the screen is blank, try pressing the "Stop" button (or press the ESCape key). What can happen is that most of the Web page comes in OK but 1 or 2 images remain to be loaded. By stopping the loading process at this point, what has already come across will be displayed and quite often this provides enough information. If the page is unreadable, try loading it again by clicking on the "Reload" button or by pulling down the View menu and choosing the Reload choice.

• WWW Search Engines
• More Netscape Features
• Building your own WWW Pages