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CS 101 – Dec. 2
• Download speed
• Internet vs. Web
• Domains
• HTML
Measuring speed
• Overhead = prepare & assemble message
• Flight time = first bit to arrive at destination
• Bandwidth = max rate to propagate data
(cruising speed)
• Total time =
overhead + flight time + (msg size)/bandwidth
How much longer?
File Size Progress “time left” rate
#1 815 KB 65.1% 3:08 1.5 KB/s
#2 5.9 MB 64.8% 24:03 1.5 KB/s
Examples
Hypertext
• A text document that contains links to other documents.
• Also may contain “multimedia”
• Filename *.html
• Software: editor…browser.
Some terminology
• Internet = global “network of networks”
• Some Internet applications:– WWW = linked documents on the Internet– E-mail– chat– FTP = file transfer prototcol
Web terminology
• HTML = standard language for hypertext
• Web page = hypertext document (*.html)
• Web site = collection of pages & folders usually starting with index.html
• Web server = machine containing site
• Web browser = program that interprets HTML to show on screen
Web addressing
• Location of file is given by a Web address or URL.
http://www.seds.org/billa/tnp/saturn.html
• saturn.html = page
• billa/tnp = folders
• www.seds.org = site [ server.place.domain]
Domains
• Three letter for U.S. (.com, .org, .net, .edu, .mil, .gov)
• Two letter for countries (.ca, .uk, .za, .ch, .de, .is, cn, .at, .us ………)
• Beware of exceptions
• Newer domains (.info, .museum, .biz, …)
Making Web pages
• Web pages written in HTML. 2 ways…
• Type in HTML code in text editor.– Enter “tags” as you go.
• Use “web generator” such as Dreamweaver– WYSIWYG
HTML format
• Web browsers read HTML files.
<html>
<head> ... </head>
<body> ... </body>
</html>
• Head section is optional• Body contains material to appear in browser
window.
Minimal example
• The simplest Web page contains text.– Can format with various font commands …
<html><body> Hello!</body> </html>
Common tags
• h1, h2, etc. = headings
• br = line break
• p = paragraph
• ol, ul, li = used for lists
• hr = horizontal rule
• b, i = bold or italic
• sub, sup = subscript or superscript
Examples
• 7 <sup> th </sup>
• Who wrote <i> Das Rheingold </i> ?
• <ul>
<li> Gold </li>
<li> Silver </li>
<li> Bronze </li>
</ul>
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