COMM 1213 H1 COMP 4923 X1

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COMM 1213 H1COMP 4923 X1

• The Internet and the Web
• (Readings Ch. 1 2 of C.D.Knuckles)

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Outline

• Technologies that we will cover
• The Internet and its components
• The Web and its components
• Webpages and their publication on the web
• Knowledge versus Information (optional)

EG
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Internet and Web Technology
Browsers
HTML
Servers
URL
TCP/IP
SQL
HTTP
Database
Applets
Cookies
Java
e-Payment
SSL
Servlets
CGI
FTP
JSPs
MIME
SMTP
XML
Authentication
POP
DW/DM
Encryption
Wireless
Pervasive Computing
Smart Cards
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Technologies that we will cover in the course

• Basic Web components
• Internet, Web, Browsers, Servers, HTTP, SSL
• Data types (text, image, video, audio)
• HTML
• Fundamentals of programming
• JavaScript

DS
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History of the Internet

• 1969 ARPANET 4 systems connected
• 1997 25 systems connected
• 1984 NSFNET 1000 servers, IPM PC arrives
• 1987 10,000 servers connected
• 1989 100,000 servers connected
• 1992 1,000,000 servers connected
• 2006 estimated at 100,000,000 servers

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E-Commerce Growth

• The Driving Force ?The Internet Economy
• To reach 50,000,000 users
• Radio took 38 years
• Computers took over 16 years
• TV took 13 years
• The Internet took 4 years!
• Over 75 of (12.3M)Canadian homes now have PCs
• Over 55 (6.7M) of those are Internet connected,
  up 51 over 2002
• Sources http//www.cbc.ca/stories/2004/07/08/cana
  da/computer_use040708
• CBC, Forrester

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Internet Economy Global Growth
1998 111M users 2000 320M users 2005 720M
users
Hyper-growth begins
150B
80
170
390
970
2,000
3,200
Source Forrester
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The Internet and its components

• How is data transmitted around the globe?
• Transmission media types?
• Digital versus analog communications
• What does it mean to have higher bandwidth?

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The Client-Server Model

• Client a machine that makes Internet requests
  for resources (printing, data, processing)
• Server a machine that performs tasks for
  clients on request and manages network resources
• Communications protocol a set of rules for two
  or more entities to converse

Comm. Protocol
Server
Client
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What is an internet?

• Communication between two or more potentially
  heterogeneous networks (LANs)
• The Internet is a set of standards for
  inter-network communications

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Architectural of the Internet
Client 1
Acadia
Server X
Application
TCP/IP
Server Y
Intranet
Internet
Client 2
Application
Server C
Server B
Server C
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TCP/IP Protocol Architecture
Transmission Control Protocol
Internet Protocol
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TCP/IP Protocol Architecture

• Internet Protocol (IP) like a postcard that
  contains
• Destination address (131.162.201.7)
• Return address
• Block of data (content)
• Transmission Control Protocol (TCP)
• Ensures the post card gets through
• Ensures the order of deliver
• Handles errors and control flow

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Client-Server Applications that use the Internet
Telnet Protocol
Telnet Window
Telnet Server
FTP
FTP Server
FTP Client
SMTP/POP
eMail Client
eMail Server
TCP
TCP
IP
IP
Internet
Network
Network
Physical
Physical
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Architecture of the Internet

• What is an IP address
• Of the form 255.255.255.255
• (32 bit address)
• Acadias IP address is what?
• 131.162.200.72

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Traffic on the Internet

• Packets and multiple paths
• Routers (demo with 4 students)
• Sending server, two routers and a receiving
  client
• Play out the request and response for a file
• What happens if a packet is lost?
• Only that packet needs to be retransmitted

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What is the Web?

• A class of applications that use the Internet
  plus a lot of new technologies and standards that
  facilitate access to resources managed by servers
  connected to the Internet
• Hardware Servers
• Software Browsers, Servers
• Protocols HTTP, HTML, MIME

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Major Architectural Components of the Web
Client 1
Browser
HTTP TCP/IP
Server A
Database Server
HTTP Server
App. Server
Internet
Client 2
Browser
index.html
URL
Server B
Server C
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Components of the Web

• Website - a collection of files and associated
  software on a server (may run on client or
  server)
• Web Server a software system that can field
  requests for website files (HTTP server) and
  applications (Application Server)
• Web Browser a GUI client application (Netscape
  Navigator, Internet Explorer) that facilitates
  access to Website files and software for display
  of data, video and audio
• Database Server provides an interface to a
  structure database for web applications

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Components of the Web

• HTTP - HyperText Transfer Protocol
• URL - Universal Resource Locator for a file on
  the internet (www.acadiau.ca)
• Webpage a representation of information
  understood by the browser
• HTML - HyperText Markup Language
• WC3 definitions For a more user friendly
  resource http//www.pierobon.org/iis/index.ht
  m

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The Web and its components

• Tower babble on the Internet
• Mix of computers, operating systems, applications
  and data formats
• Required a lot of special knowledge to acces
  information
• ftp, telnet, news, mail, file
• URL Universal Resource Locator
• How//Where/What
• http//plato.acadiau.ca/courses/comp/dsilver/4923/
  
• ftp//plato.acadiau.ca
• file//C\Documents and Settings\dsilver\My
  Documents

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Named Addresses and Domains

• http//131.162.200.72 is too difficult to
  remember, so a naming systems was conceived
  http//www.acadiau.ca
• Domain names have advantages
• Easier market Not case sensitive
• One IP can have several domain names
• How are domain names resolved?
• Domain Name Server (DNS)
• How are they established?
• Registration service

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Finding out about domain names

• http//www.keytlaw.com/urls/whoowns.htm
• http//www.hcidata.co.uk/host2ip.htm
• Does someone own your domain name?

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WWW and Platform Independence

• Definition An application is a software program
• Written for a particular operating system
• MS Windows, Apple Mac, Linux, Unix
• Windows programs will not run on a Mac
• They are platform dependent
• In contrast, browsing the web is platform
  independent
• So are browsers platform independent?

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ASCII Text files

• Open the window Notepad application
• Type This is a simple text file.
• Close and save the file as simple.html on your
  desktop
• We will use this to build our first series web
  pages .. because web pages are written in ASCII
  text
• Click on simple.html on your desktop

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Stay away from MS Word!

• TRY-IT Compare simple.html with a Word file
  simple.doc opened with Notepad
• Dont use Word for simple text or HTML

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How did simple.html become a webpage?

• The browser is smart enough to recognize that
  this is not really HTML so defaults to displaying
  ASCII text
• But how do we get it on a server?

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Public Directories and Web Servers

• Requires an account on a computer connected to
  the Internet that is web server ready
• Computer accounts have an associated
• Root directory such as dsilver or 066525m
• User/password such as 066525m/secret
• Do you have an account on such a server at
  Acadia?
• Try http//axe.acadiau.ca/

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Your account and website at Acadia

• Open My Computer and look for something like
• 066525m on Axe\Dat\User\Cstudent (H)
• While connected to the network drive H
• on you computer is linked to your Axe
• Server and your root directory
• If you do not see this then
• Find the read N in the Windows tray at the
  bottom
• Right click and choose Network Login

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Your account and website at Acadia

• Lets put something on the web
• By convention web files must be placed in a
  subdirectory called WWW
• Create this subdirectory using File/New from the
  My Computer window
• Just copy and paste simple.html from your desk
  top into WWW
• Lets view it
• Yours http//axe.acadiau.ca/066525m/simple.ht
  ml
• Mine http//ace.acadiau.ca/dsilver/simple.ht
  ml

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Hiding Web Directories

• Normally you do not wish web servers to see
  everything your web dircetory
• Solution
• Rename simple.html to index.html
• Now browse for
• http//axe.acadiau.ca/066525m/simple.html
• http//ace.acadiau.ca/dsilver/
• Why does this work?
• The server knows to look for index.html as a
  default
• No other files can be seen

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FTP Upload of a file

• FTP File Transport Protocol (1980s)
• Put upload to server
• Get download from server
• You can download and install a free FTP client to
  your computer call ws_ftp
• Demo of ws_ftp

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Internet Security Risks

• Downloading files to your computer is normally
  not harmful
• Opening or executing files can put your laptop at
  risk when outside the browser
• Examples
• Files saved from your browser to the HD
• FTPed files
• Email attachments (spam)
• In genera, if you are uncertain of the
  server/sender, do not open the file.

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How does a web page get from the server to my
browser?

• HTTP Hyper Text Transport Protocol
• Key to Web technology
• Browser issues a get HTTP request for
• http//axe.acadiau.ca/066525m/simple.html
• how//-----where-----/-------what---------------
• Internet delivers the request to Axe server using
  TCP/IP
• Axe server finds the simple.html file
• Axe server sends a HTTP response back to your
  laptops IP address
• The page is then cashed in your browsers
  temporary memory and displayed

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HTTPHyperText Transfer Protocol

• The application protocol of the Web
• Like FTP it is layered on top of TCP/IP

HTTP
Web Browser
HTTP Server
TCP
TCP
IP
IP
Internet
Network
Network
Physical
Physical