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<title>Web Programming Step by Step, Lecture 1: Internet/WWW; HTML Basics</title>
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<h1><em>Web Programming Step by Step</em>, Chapter 1</h1>
<h2>Internet/WWW; HTML Basics</h2>
</div>
</div>
<div class="presentation">
<div class="slide">
<h1><a href="http://www.webstepbook.com/">Web Programming Step by Step</a></h1>
<h3>Lecture 1<br /> Internet/WWW; HTML Basics</h3>
<h4>Reading: Chapter 1; 2.1</h4>
<p class="license">
Except where otherwise noted, the contents of this presentation are Copyright 2010 Marty Stepp and Jessica Miller.
</p>
<div class="w3c">
<a href="http://validator.w3.org/check/referer"><img src="images/w3c-xhtml11.png" alt="Valid XHTML 1.1" /></a>
<a href="http://jigsaw.w3.org/css-validator/check/referer"><img src="images/w3c-css.png" alt="Valid CSS!" /></a>
</div>
</div>
<div class="slide titleslide">
<h1>1.1: The Internet</h1>
<ul>
<li>
<strong>1.1: The Internet</strong>
</li>
<li>
1.2: The World Wide Web (WWW)
</li>
<li>
2.1: Basic HTML
</li>
</ul>
</div>
<div class="slide">
<h1>The Internet</h1>
<div class="centerfigure">
<img src="images/internet.png" alt="The Internet" />
</div>
<ul>
<li>Wikipedia: <a href="http://en.wikipedia.org/wiki/Internet">http://en.wikipedia.org/wiki/Internet</a></li>
<li>a connection of computer networks using the Internet Protocol (IP)</li>
<li>What's the difference between the Internet and the World Wide Web (WWW)?</li>
</ul>
<div class="handout">
<ul>
<li>the Web is the collection of web sites and pages around the world; the Internet is larger and also includes other services such as email, chat, online games, etc.</li>
</ul>
</div>
</div>
<div class="slide">
<h1>
Brief history
<span class="readingsection">(1.1.1)</span>
</h1>
<ul>
<li>began as a US Department of Defense network called <a href="http://en.wikipedia.org/wiki/ARPANET">ARPANET</a> (1960s-70s)</li>
<li>initial services: electronic mail, file transfer</li>
<li>opened to commercial interests in late 80s</li>
<li>WWW created in 1989-91 by <a href="http://en.wikipedia.org/wiki/Tim_Berners-Lee">Tim Berners-Lee</a></li>
<li>popular web browsers released: Netscape 1994, IE 1995</li>
<li>Amazon.com opens in 1995; Google January 1996</li>
<li class="incremental"><a href="http://www.webhamster.com/">Hamster Dance</a> web page created in 1999 <img src="images/hamster_dance.png" alt="hamster dance" class="incremental" style="vertical-align: top" /></li>
</ul>
</div>
<div class="slide">
<h1>Key aspects of the internet</h1>
<ul>
<li>subnetworks can stand on their own</li>
<li>computers can dynamically join and leave the network</li>
<li>built on open standards; anyone can create a new internet device</li>
<li>lack of centralized control (mostly)</li>
<li>everyone can use it with simple, commonly available software</li>
</ul>
</div>
<div class="slide">
<h1>
People and organizations
<span class="readingsection">(1.1.2)</span>
</h1>
<ul>
<li>Internet Engineering Task Force (<a href="http://en.wikipedia.org/wiki/Internet_Engineering_Task_Force">IETF</a>): internet protocol standards</li>
<li>Internet Corporation for Assigned Names and Numbers (<a href="http://en.wikipedia.org/wiki/ICANN">ICANN</a>): <br />
decides top-level <a href="http://news.com.com/ICANN+rejects+.xxx+domain/2100-1047_3-6071124.html">domain names</a></li>
<li>World Wide Web Consortium (<a href="http://en.wikipedia.org/wiki/World_Wide_Web_Consortium">W3C</a>): web standards</li>
</ul>
<div class="centerfigure">
<img src="images/ietf_logo.gif" alt="IETF" />
<img src="images/icann.jpg" alt="ICANN" />
<img src="images/w3c.png" alt="W3C" />
</div>
</div>
<div class="slide">
<h1>
Layered architecture
<span class="readingsection">(1.1.3)</span>
</h1>
<p>
The internet uses a layered hardware/software architecture (also called the "OSI model"):
<img class="rightfigure" src="images/osi_model.png" alt="OSI model" />
</p>
<ul>
<li><em>physical layer</em> : devices such as ethernet, coaxial cables, fiber-optic lines, modems</li>
<li><em>data link layer</em> : basic hardware protocols (ethernet, wifi, DSL PPP)</li>
<li><em>network / internet layer</em> : basic software protocol (IP)</li>
<li><em>transport layer</em> : adds reliability to network layer (TCP, UDP)</li>
<li><em>application layer</em> : implements specific communication for each kind of program (HTTP, POP3/IMAP, SSH, FTP)</li>
</ul>
</div>
<div class="slide">
<h1>Internet Protocol (<a href="http://en.wikipedia.org/wiki/Internet_Protocol">IP</a>)</h1>
<ul>
<li>a simple protocol for attempting to send data between two computers</li>
<li>each device has a 32-bit IP address written as four 8-bit numbers (0-255) <br />
<img src="images/fig1_ip_address.png" alt="IP address" style="width: 507px; margin-top: 20px;" />
</li>
<li>find out your internet IP address: <a href="http://www.whatismyip.com/">whatismyip.com</a></li>
<li>find out your local IP address:
<ul>
<li>in a terminal, type: <code>ipconfig</code> (Windows) or <code>ifconfig</code> (Mac/Linux)</li>
</ul>
</li>
</ul>
</div>
<div class="slide">
<h1>Transmission Control Protocol (<a href="http://en.wikipedia.org/wiki/Tcp_protocol">TCP</a>)</h1>
<ul>
<li>adds multiplexing, guaranteed message delivery on top of IP</li>
<li>
<strong>multiplexing</strong>: multiple programs using the same IP address
<ul>
<li><strong>port</strong>: a number given to each program or service</li>
<li>port 80: web browser (port 443 for secure browsing)</li>
<li>port 25: email</li>
<li>port 22: ssh</li>
<li>port 5190: AOL Instant Messenger</li>
<li><a href="http://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers">more common ports</a></li>
</ul>
</li>
<li>some programs (games, streaming media programs) use simpler <a href="http://en.wikipedia.org/wiki/User_Datagram_Protocol">UDP</a> protocol instead of TCP</li>
</ul>
</div>
<div class="slide titleslide">
<h1>1.2: The World Wide Web (WWW)</h1>
<ul>
<li>
1.1: The Internet
</li>
<li>
<strong>1.2: The World Wide Web (WWW)</strong>
</li>
<li>
2.1: Basic HTML
</li>
</ul>
</div>
<div class="slide">
<h1>
<a href="http://en.wikipedia.org/wiki/Web_server">Web servers</a> and
<a href="http://en.wikipedia.org/wiki/Web_browser">browsers</a>
<span class="readingsection">(1.2.1)</span>
</h1>
<div class="topfigure">
<img src="images/webserver.gif" alt="web server" />
</div>
<ul>
<li>
<strong>web server</strong>: software that listens for web page requests
<ul>
<li><a href="http://www.apache.org">Apache</a></li>
<li>Microsoft Internet Information Server (IIS) (<a href="http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/iiiisin2.mspx?mfr=true">part of Windows</a>)</li>
</ul>
</li>
<li><strong>web browser</strong>: fetches/displays documents from web servers
<img class="rightfigure" src="images/web_browser.jpg" alt="Firefox web browser" />
<ul>
<li><a href="http://www.getfirefox.com/">Mozilla Firefox</a></li>
<li>Microsoft <a href="http://www.microsoft.com/windows/products/winfamily/ie/">Internet Explorer</a> (IE)</li>
<li>Apple <a href="http://www.apple.com/safari/">Safari</a></li>
<li><a href="http://www.google.com/chrome/">Google Chrome</a></li>
<li><a href="http://www.opera.com/">Opera</a></li>
</ul>
</li>
</ul>
</div>
<div class="slide">
<h1>
Domain Name System (<a href="http://en.wikipedia.org/wiki/Dns">DNS</a>)
<span class="readingsection">(1.2.2)</span>
</h1>
<ul>
<li>a set of servers that map written names to IP addresses
<ul>
<li>Example: <code>www.cs.washington.edu</code> → <code>128.208.3.88</code></li>
</ul>
</li>
<li>many systems maintain a local cache called a <a href="http://en.wikipedia.org/wiki/Hosts_file">hosts file</a>
<ul>
<li>Windows: <code><a href="file:///C:/Windows/system32/drivers/etc/hosts">C:\Windows\system32\drivers\etc\hosts</a></code></li>
<li>Mac: <code><a href="file:///private/etc/hosts">/private/etc/hosts</a></code></li>
<li>Linux: <code><a href="file:///etc/hosts">/etc/hosts</a></code></li>
</ul>
</li>
</ul>
</div>
<div class="slide">
<h1>Uniform Resource Locator (<a href="http://en.wikipedia.org/wiki/Url">URL</a>)</h1>
<ul>
<li>an identifier for the location of a document on a web site</li>
<li>
a basic URL:
<pre>
<a href="http://www.aw-bc.com/info/regesstepp/index.html">http://www.aw-bc.com/info/regesstepp/index.html</a>
~~~~ ~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~
protocol host path
</pre>
</li>
<li>
upon entering this URL into the browser, it would:
<ul>
<li>ask the DNS server for the IP address of <code>www.aw-bc.com</code></li>
<li>connect to that IP address at port 80</li>
<li>ask the server to <code>GET /info/regesstepp/index.html</code></li>
<li>display the resulting page on the screen</li>
</ul>
</li>
</ul>
</div>
<div class="slide">
<h1>More advanced URLs</h1>
<ul>
<li>
<strong>anchor</strong>: jumps to a given section of a web page
<pre>
<a href="http://www.textpad.com/download/index.html#downloads">http://www.textpad.com/download/index.html<strong>#downloads</strong></a>
</pre>
<ul>
<li>fetches <code>index.html</code> then jumps down to part of the page labeled <code>downloads</code></li>
</ul>
</li>
<li>
<strong>port</strong>: for web servers on ports other than the default 80
<pre>
http://www.cs.washington.edu<strong>:8080</strong>/secret/money.txt
</pre>
</li>
<li>
<strong>query string</strong>: a set of parameters passed to a web program
<pre>
<a href="http://www.google.com/search?q=miserable+failure&start=10">http://www.google.com/search<strong>?q=miserable+failure&start=10</strong></a>
</pre>
<ul>
<li>parameter <code>q</code> is set to <code>"miserable+failure"</code></li>
<li>parameter <code>start</code> is set to <code>10</code></li>
</ul>
</li>
</ul>
</div>
<div class="slide">
<h1>
Hypertext Transport Protocol
(<a href="http://en.wikipedia.org/wiki/Http_protocol">HTTP</a>)
<span class="readingsection">(1.2.3)</span>
</h1>
<ul>
<li>the set of commands understood by a web server and sent from a browser</li>
<li>
some HTTP commands (your browser sends these internally):
<ul>
<li><code>GET <em>filename</em></code> : download</li>
<li><code>POST <em>filename</em></code> : send a web form response</li>
<li><code>PUT <em>filename</em></code> : upload</li>
</ul>
</li>
<li>
simulating a browser with a terminal window:
<pre class="examplecode shell">
$ <em>telnet www.cs.washington.edu 80</em>
Trying 128.208.3.88...
Connected to 128.208.3.88 (128.208.3.88).
Escape character is '^]'.
<em>GET /index.html</em>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 ...">
<html>
...
</pre>
</li>
</ul>
</div>
<div class="slide">
<h1>HTTP error codes</h1>
<ul>
<li>when something goes wrong, the web server returns a special "error code" number to the browser, possibly followed by an HTML document</li>
<li>common error codes:
<table class="standard">
<tr>
<th class="spaced">Number</th><th>Meaning</th>
</tr>
<tr>
<td>200</td>
<td>OK</td>
</tr>
<tr>
<td><a href="http://clsc.net/research/google-302-page-hijack.htm">301-303</a></td>
<td>page has moved (permanently or temporarily)</td>
</tr>
<tr>
<td><a href="http://www.cs.washington.edu/education/courses/cse190d/07sp/lectures/">403</a></td>
<td>you are forbidden to access this page</td>
</tr>
<tr>
<td><a href="http://www.homestarrunner.com/404.html">404</a></td>
<td>page not found</td>
</tr>
<tr>
<td>500</td>
<td>internal server error</td>
</tr>
<tr>
<td colspan="2" class="completelist"><a href="http://en.wikipedia.org/wiki/Http_error_codes">complete list</a></td>
</tr>
</table>
</li>
</ul>
</div>
<div class="slide">
<h1>Internet media ("<a href="http://en.wikipedia.org/wiki/Mime_type">MIME</a>") types</h1>
<ul>
<li>
sometimes when including resources in a page (style sheet, icon, multimedia object), we specify their type of data
<table class="standard">
<tr>
<th>MIME type</th>
<th class="slidetable">file extension</th>
</tr>
<tr class="code">
<td>text/html</td><td>.html</td>
</tr>
<tr class="code">
<td>text/plain</td><td>.txt</td>
</tr>
<tr class="code">
<td>image/gif</td><td>.gif</td>
</tr>
<tr class="code">
<td>image/jpeg</td><td>.jpg</td>
</tr>
<tr class="code">
<td>video/quicktime</td><td>.mov</td>
</tr>
<tr class="code">
<td>application/octet-stream</td><td>.exe</td>
</tr>
</table>
</li>
<li>Lists of MIME types: <a href="http://www.w3schools.com/media/media_mimeref.asp">by type</a>, <a href="http://www.webmaster-toolkit.com/mime-types.shtml">by extension</a></li>
</ul>
</div>
<div class="slide">
<h1>
Web languages / technologies
<span class="readingsection">(1.2.4)</span>
</h1>
<ul>
<li>Hypertext Markup Language (<a href="http://en.wikipedia.org/wiki/Html">HTML</a>): used for writing web pages</li>
<li>Cascading Style Sheets (<a href="http://en.wikipedia.org/wiki/Cascading_Style_Sheets">CSS</a>): stylistic info for web pages</li>
<li>PHP Hypertext Processor (<a href="http://www.php.net/">PHP</a>): dynamically create pages on a web server</li>
<li><a href="http://en.wikipedia.org/wiki/JavaScript">JavaScript</a>: interactive and programmable web pages</li>
<li>Asynchronous JavaScript and XML (<a href="http://en.wikipedia.org/wiki/Ajax_%28programming%29">Ajax</a>): accessing data for web applications</li>
<li>eXtensible Markup Language (<a href="http://en.wikipedia.org/wiki/Xml">XML</a>): metalanguage for organizing data</li>
<li>Structured Query Language (<a href="http://en.wikipedia.org/wiki/Sql">SQL</a>): interaction with databases</li>
</ul>
</div>
<div class="slide titleslide">
<h1>2.1: Basic HTML</h1>
<ul>
<li>
1.1: The Internet
</li>
<li>
1.2: The World Wide Web (WWW)
</li>
<li>
<strong>2.1: Basic HTML</strong>
</li>
</ul>
</div>
<div class="slide">
<h1>
Hypertext Markup Language (<a href="http://www.w3schools.com/html/default.asp">HTML</a>)
<span class="readingsection">(2.1.1)</span>
</h1>
<ul>
<li>describes the <em>content</em> and structure of information on a web page
<ul>
<li>not the same as the <em>presentation</em> (appearance on screen)</li>
</ul>
</li>
<li>surrounds text content with opening and closing <span class="term">tags</span></li>
<li>each tag's name is called an <span class="term">element</span>
<ul>
<li>syntax: <code><</code><var>element</var><code>></code> <var>content</var> <code></</code><var>element</var><code>></code></li>
<li>example: <code><em><p></em>This is a paragraph<em></p></em></code></li>
</ul>
</li>
<li>most whitespace is insignificant in HTML (ignored or collapsed to a single space)</li>
<li>we will use a stricter, more standard version called <a href="http://www.w3schools.com/xhtml/xhtml_html.asp">XHTML</a></li>
</ul>
</div>
<div class="slide">
<h1>
Structure of an HTML page
<span class="readingsection">(2.1.2)</span>
</h1>
<pre class="syntaxtemplate html">
<html>
<head>
<var>information about the page</var>
</head>
<body>
<var>page contents</var>
</body>
</html>
</pre>
<ul>
<li>the <span class="term">header</span> describes the page and the <span class="term">body</span> contains the page's contents</li>
<li>an HTML page is saved into a file ending with extension <code>.html</code></li>
<li class="incremental">but this is not quite the syntax we'll use... (see next slide)</li>
</ul>
</div>
<div class="slide">
<h1>
Structure of an XHTML page
<span class="readingsection">(2.1.2)</span>
</h1>
<pre class="syntaxtemplate html">
<em><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"></em>
<html <em>xmlns="http://www.w3.org/1999/xhtml"</em>>
<head>
<var>information about the page</var>
</head>
<body>
<var>page contents</var>
</body>
</html>
</pre>
<ul>
<li>the <code>DOCTYPE</code> and <code>xmlns</code> additions tell the browser to interpret our page's code as XHTML, the latest/greatest standard version of the language</li>
</ul>
</div>
<div class="slide">
<h1>Page title: <a href="http://www.w3schools.com/tags/tag_title.asp"><code><title></code></a></h1>
<p class="description">describes the title of the web page</p>
<pre class="examplecode html">
<em><title></em>Chapter 2: HTML Basics<em></title></em>
</pre>
<ul>
<li>placed within the <code>head</code> of the page</li>
<li>displayed in the web browser's title bar and when bookmarking the page</li>
</ul>
</div>
<div class="slide">
<h1>
Paragraph:
<a href="http://www.w3schools.com/tags/tag_p.asp"><code><p></code></a>
<span class="readingsection">(2.1.3)</span>
</h1>
<p class="description">paragraphs of text (block)</p>
<div class="example">
<pre class="examplecode html">
<em><p></em>You're not your job.
You're not how much money you have in the bank.
You're not the car you drive. You're not the contents
of your wallet. You're not your khakis. You're
the all-singing, all-dancing crap of the world.<em></p></em>
</pre>
<div class="exampleoutput insertoutput"></div>
</div>
<!--
<p>
You're not your job. You're not how much money you have in the bank. You're not the car you drive. You're not the contents of your wallet. You're not your khakis. You're the all-singing, all-dancing crap of the world.
</p>
-->
<ul>
<li>placed within the <code>body</code> of the page</li>
<li><a href="http://www.w3schools.com/tags/tryit.asp?filename=tryhtml_paragraphs2">more paragraph examples</a></li>
</ul>
</div>
<div class="slide">
<h1>
Headings:
<a href="http://www.w3schools.com/tags/tag_h1.asp"><code><h1></code></a>,
<a href="http://www.w3schools.com/tags/tag_h2.asp"><code><h2></code></a>, ...,
<a href="http://www.w3schools.com/tags/tag_h2.asp"><code><h6></code></a>
</h1>
<p class="description">headings to separate major areas of the page (block)</p>
<div class="example">
<pre class="examplecode html">
<em><h1></em>University of Whoville<em></h1></em>
<em><h2></em>Department of Computer Science<em></h2></em>
<em><h3></em>Sponsored by Micro$oft<em></h3></em>
</pre>
<div class="exampleoutput insertoutput"></div>
</div>
<ul>
<li><a href="http://www.w3schools.com/tags/tryit.asp?filename=tryhtml_headers">More heading examples</a></li>
</ul>
</div>
<div class="slide">
<h1>
Horizontal rule:
<a href="http://www.w3schools.com/tags/tag_p.asp"><code><hr></code></a>
</h1>
<p class="description">a horizontal line to visually separate sections of a page (block)</p>
<div class="example">
<pre class="examplecode html">
<p>First paragraph</p>
<em><hr /></em>
<p>Second paragraph</p>
</pre>
<div class="exampleoutput insertoutput"></div>
</div>
<ul>
<li>should be immediately closed with <code> /></code></li>
</ul>
</div>
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