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CompSci 001 2.1
Today’s topics
Networks & the InternetBasic HTML
The basis for web pages “Almost” programming
Upcoming Connections Algorithms
ReadingInternet history readingsGreat Ideas Chapters 1Computer Science, Chapter 4
CompSci 001 2.2
Networks
Need to communicate. How to do it? Robustly, efficiently, securely
Classifications LAN vs. WAN Closed (proprietary) vs. Open
Topologies
CompSci 001 2.3
The Internet
Network of networks Connect networks through routers and bridges Internet: Started by DARPA in 1973
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
CompSci 001 2.4
The World Wide Web
Servers disseminate hypertext documents Hypertext is text with a link or reference Uniform resource locator (URL): unique address of
data on web HyperText Markup Language (HTML) is a common
formatting language for the web Tags are non-printing formatting markers
• Identified by angle brackets (i.e. <TAG> )• Example: <TITLE>The Human Tornado</TITLE>• Come in delimiting pair
General Goals Platform independent Text Specification
(also called a Markup Language) Links to other network resources
CompSci 001 2.5
Delimiting with tags First tag says, “Begin mode” Second tag (containing “/”) says, “End mode” So <TITLE>The Human Tornado</TITLE> means
1. Begin title mode2. The text “The Human Tornado” is in title mode3. End title
Using this construct, we can nest several different modes and have interesting behavior
Good tutorials on HTMLhttp://www.w3.org/MarkUp/Guide/http://archive.ncsa.uiuc.edu/General/Internet/WWW/HTMLPrimer.html
http://www.w3schools.com/html/ In lab, you will create a webpage
CompSci 001 2.6
HTML
Some General HTML rules For tags, case doesn’t matter, e.g., <html> = <HTML>
In the text, spaces don’t matter: it will decide!
(we call that “free format”) <br> starts a new line
Headings Use <hn> to specify heading where smaller n designates more important heading
For example <h1> - - - </h1> is largest, boldest heading
<h4> - - - </h4> designates a fairly minor heading
CompSci 001 2.7
HTML Basic Web Page Structure<html><head><title> Ted’s Home Page </title></head><body bgcolor=”White”><center> <h1> Ted’s Page </h1> </center>Welcome to Duke University! <br><i> more to come … </i></body></html>
CompSci 001 2.8
HTML
Want to link things together! Hypertext (from the Webopedia)
A special type of database system, invented by Ted Nelson in the 1960s, in which objects (text, pictures, music, programs, and so on) can be creatively linked to each other.
An anchored link:<a HREF=”http://www.duke.edu”>The Duke Web Page</a> Produces link to URL specified in HREF and display info between <a> tags: The Duke Web Page
CompSci 001 2.9
HTML
Other useful info For italics or emphasis use
<i> or <em> For darker or bold use
<strong> or <b> For text space exactly as typed (not free
format) use<pre>
CompSci 001 2.10
HTML
Specifying Colors Can be specified in different ways e.g., for standard colors can specify “white” or “red”
Can specify arbitrary colors by specifying the amount of red, blue, and green involved. (RGB)
Uses base 16 arithmetic: 0, 1, …, 9, a, b, c, d, e, f
Red: “ff0000” Green: “00ff00” Blue: “0000ff”Black: “000000” Gray: ”7f7f7f” White:”ffffff”
Yellow: ”ffff00” Orange: “ff7f00” Purple: ”c000e0”
Can experiment!
CompSci 001 2.11
HTML More useful HTML
Bulleted list <ul> … </ul>
– <li> for items• - - -• - - -• - - -
Ordered list <ol> … </ol>1. - - -2. - - -3. - - -
Can nest arbitrarily deep - - lists within lists
Tables<table border=1>
<tr> <td> Cell 1 </td>
<td> Cell 2 </td> </tr>
<tr> <td> Cell 3 </td>
<td> Cell 4 </td>
</tr>
</table>
produces simple table Images<img
src=”http://www.cs.duke.edu/~forbes/construct.gif”>
displays image
CompSci 001 2.12
HTML/Web/UNIX practice In UNIX, your web page folder is found in a standard
location: ~userID/public_html/and for OIT Duke files is accessed with a web
browser at //www.duke.edu/~userID
Many people don’t code in raw HTML Write in TextPad Save as Web Page in Microsoft Word Netscape Composer, Macromedia Dreamweaver,
Bluefish These all generate HTML for you View other people’s web page source (HTML) from most
browsers -- learn from others
CompSci 001 2.13
More Hexadecimal
from L. Snyder, Fluency with Information Technology
CompSci 001 2.14
Cascading Style Sheets (CSS)
Style sheets describe how documents are presented
CSS is a standard for providing formatting (i.e. style) information for web documents Specify fonts, colors, spacing, etc. Why would we want to separate the style information from the content?
In the CSS file, you specify: a selector, that picks out the element you want
the properties and values that you want to apply to the selected element (or elements)
body { font-family: serif;}
select everything in the <body> tagand use a serif font for the text
from © 2006 DW Johnson & University of Washingtonton
CompSci 001 2.15
The element type: body, div, span, h1, h2, img, p, a, …
Specific "id" given for the element
General "class" given for the element
Selectors
<div id="footer">…</div>
div#footer { font-family: sans-serif;}
selected with
html file css file
<h1>Introduction</h1>h1 { color: green;}
selected with
html file css file
<span class="familyMember">…</span>
span.familyMember { font-weight: bold;}
selected with
html file
css file
from © 2006 DW Johnson & University of Washingtonton
CompSci 001 2.16
Properties The properties of the element determine how it it styled,
including: background of the element text colors, alignment, spacing font selection border thickness, color, style padding and margins around the element list styles
Some properties and their valuescolor: and background-color:and norder-color
aqua, black, blue, fuchsia, gray, green, lime, maroon, navy, olive, orange, purple, red, silver, teal, white, and yellow
font-family:serif, sans-serif, cursive, fantasy, monospace
font-style:normal, italic
font-weight:normal, bold
border-width:thin, medium, thick
border-style:none, hidden, dotted, dashed, solid, double, groove, ridge, inset, outset
See Prelab 1 for CSS tutorials
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