HCI 201
Multimedia and The World Wide Web
The Internet
History of Internet
Started 1960s - Packet SwitchingResearch project by
U.S. Department of DefenseARPAnet
(Advanced Research Projects Agency)Really took off in 1993
History of the World Wide Web CERN (Tim Berners-Lee)
developed authoring language and distribution system for creating and sharing multimedia-enabled, integrated electronic documents over the Internet
World Wide Web and HTML was born
Allows relationships between documents and elements
NCSA developed Mosaic to view these documents
Overview
The Internet The WWWHow does it all work?
Hardware Software Networking Protocols
Internet and World Wide Web
What’s the difference between the two terms?
The Internet and the WWW
The Internet (late 60s): “It’s a worldwide collection of computer networks – a network of networks – sharing digital information via a common set of networking and software protocols.” HTML & XHTML – The Definitive Guide
The World Wide Web (early 90s): the monster application that runs on the Internet infrastructure (over 2 billion pages). With the invention of GUI -> color, voice and video were
added to the Internet.
History of the Internet
Started 1960s - Packet SwitchingResearch project by
U.S. Department of DefenseARPAnet
(Advanced Research Projects Agency)Really took off in 1993, why?
http://www.isoc.org/internet/history/ URL
History of the World Wide Web
CERN (Tim Berners-Lee) developed authoring language and distribution system for creating and sharing multimedia-enabled, integrated electronic documents over the Internet
World Wide Web and HTML was born. Allows relationships between documents and
elements. NCSA developed Mosaic to view these docs.
http://www.isoc.org/internet/history/ URL
Overview
The Internet The WWWHow does it all work?
Hardware Software Networking Protocols
Hardware
The difference between hardware and software is you can touch hardware.
The hardware you need to be connected to the Internet is A computer A networking device, e.g. a modem or network card A connection, e.g.
At home, an Internet Service Provider At school, a LAN connection
Telephone (Dial-Up) Modem: Low Speed but Inexpensive & Widely Available
Modem - device that sends and receives data over telephone lines to and from computers
Most modems today have a maximum speed of 56 Kbps.
Internet Service Provider (ISP)
ISP - a company that connects you through your communications line to its servers, or central computer, which connect you to the Internet via another company’s network access points
Software
Software is a term used to describe programs that allow the hardware to do things for you.
You need a few pieces of software to connect to the Internet An operating system, e.g. Windows XP A browser, e.g. Internet Explorer, Firefox, Opera
If you want to develop web sites or pages, you need a few more Authoring tool, e.g. Notepad, Dreamweaver or Frontpage FTP program, to transfer files from your client machine (in
front of you) to the server (your students account), e.g. SSH
Protocols
Because networks use a wide variety of hardware and software, protocols are needed to coordinate communication and data transmission.
A protocol is a set of rules for the exchange of data across communication lines.
Protocols make the whole thing work!
Standards Organizations
World Wide Web Consortium (W3C)Internet Engineering Task Force (IETF)
http://www.w3c.org
http://www.ietf.org
URL
What protocols doIdentify the different devices in the
communication path.Establish the speed and method for
transmission of data.Alert the receiving device to the incoming data.Determine the method of error checking and
correction.
HyperText Transfer Protocol
HTTP is the protocol responsible for transferring and displaying web pages.
HTTP uses the client/server model of computing. The client is the user’s web browser:
a software program that retrieves the page and displays it. (I.E, Netscape). A Web browser can either be text-based, or graphical.
A Web page is stored on a Web server, which makes the page available to users of the Web.
The server is the web server where the page resides. (Ex: www.nyt.com)
TCP/IP protocol
TCP – Transmission Control Processing IP – Internet Protocol
TCP: Rules to control on how messages are broken down into packets, and then reassembled at the final destination.
IP: Rules to label packets for delivery and to control the packet’s path from sender to recipient.
TCP/IP software processes data transmission through the Internet.
Internet protocols
Simple Mail Transfer Protocol (SMTP): transferring email messages from one machine to another
File Transfer Protocol (FTP): transferring files between local and remote machines.
Telnet: a terminal emulation protocol used to remote login.
Others?
TCP/IP
HTTP
POP
IP addresses: dotted quads
Each node in the IP world is identified by a unique 32-bit number called an IP address.
IP addresses appear as a series of four 8-bit numbers separated by dots (dotted quads). Each number ranges from 0 to 255.14.192.1.100 students.cs.depaul.edu
IP addresses are usually assigned human-readable names (domain names).
IP Address
126.12.1.7
126.1.1.1
126.12.1.1
126.12.1.2126.12.1.3
126.12.1.4
126.12.1.5126.12.1.6
15.35.200.1
15.35.200.2
15.35.200.3
132.12.1.6
132.12.1.5
132.12.1.4
132.12.1.3
132.12.1.2
132.12.1.7
132.12.1.1 245.12.50.5
245.12.50.6
245.12.50.7
245.12.50.8
245.12.50.9
152.123.200.1
152.124.20.2
152.124.20.3
152.124.20.4
152.124.20.5
152.124.20.6152.124.20.7
152.124.20.8
146.182.0.1
146.182.0.2
146.182.0.3
146.182.0.4
146.182.0.5
146.182.0.6
146.182.0.7
146.182.5.5145.12.50.1
172.11.11.1
172.11.11.2
172.11.11.3
172.11.11.4172.11.11.5
172.11.11.6
172.11.11.7
172.11.11.8
172.11.11.9
172.11.11.10
172.11.11.11
172.11.11.12
172.11.11.13
172.11.11.14
172.11.11.15
172.11.11.16
Domain Name Server (DNS)
www.yahoo.com(Domain Name)
64.58.76.223(IP Address)
IP addresses are hard to remember.
amazon.com
yahoo.com
microsoft.com
depaul.edu
chicago.com
news.com
cnn.com
Domain
Amazon. COM
yahoo.com
microsoft.com
depaul.edu
chicago.com
news.com
cnn.com
Domain Name
www.yahoo.com
www.cti.depaul.edu
www.depaul.edu
www.chicago.com
www.microsoft.com
Domain Name Server
A Domain Name Server is responsible for the mapping between domain names and IP addresses.
bach.cs.depaul.edu
Org. type (top level domain)
Organization name
Organization name
Host name
IP address: 140.192.33.6
.com
.org
.gov
.mil
.net
.fr
.museum
.biz
A Typical HTTP Exchange
Client: Please open a connectionto ‘www.nytimes.com’ and send methe default file. I am located at IP Address 140.192.1.6.
Netscape’s URL Window
NY TimesWeb Server
Server: Let me check…. Okay, the default file at this site is of type HTML. It is 1749 bytes in size. Thedate is Tue, May 2nd at 15:33:33.
NY Times Web Page
Web Pages and Web Browsers
A Web page is stored on a Web server, which makes the page available to users of the Web.
To view a Web page, the user runs a Web browser, a software program that retrieves the page and displays it.
A Web browser can either be text-based, or graphical.
URL: Uniform Resource Locator• People on the Web use a naming convention
called the uniform resource locator (URL).
• A URL consists of at least two and as many as four parts.
• A simple two part URL contains the protocol used to access the resource followed by the location of the resource.
Example: http://www.cs.depaul.edu/
• A more complex URL may have a file name and a path where the file can be found.
http://facweb.cs.depaul.edu/aburns/research/res_interests.html
domainThe protocol
used path that indicates the location of the document in the host’s file system
documentname
A Web URL deconstructed
The user is a directory in the system
aburns @ cs . depaul . edu
HandleHost/Server Domain
Top leveldomain
Others:• students• hawk• condor
Others:• com, net, org,• mil, gov• fr, uk, dz• info, biz, name,pro, museum, coop
Anatomy of an e-mail address