Comp4 Unit2a Lecture Slides

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Introduction to Information and Computer Science Internet and the World Wide Web Lecture a This material (Comp4_Unit2a) was developed by Oregon Health and Science University, funded by the Department of Health and Human Services, Office of the National Coordinator for Health Information Technology under Award Number IU24OC000015

Transcript of Comp4 Unit2a Lecture Slides

Page 1: Comp4 Unit2a Lecture Slides

Introduction to Information and Computer Science

Internet and the World Wide Web

Lecture a

This material (Comp4_Unit2a) was developed by Oregon Health and Science University, funded by the Department of Health and Human Services, Office of the National Coordinator for Health Information Technology under Award Number

IU24OC000015

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Internet and the World Wide WebLearning Objectives

• Define the Internet and how to connect to it (Lecture a and b)

• Define the World Wide Web and how to access it (Lecture a and b)

• Write effective search queries for Internet search engines, filter the results, and evaluate credibility of information (Lecture b)

• Discuss security and privacy concerns on the Internet (Lecture c)

• Describe ethical issues for the Internet (Lecture c and d)• Explore online healthcare applications and associated

security and privacy issues including HIPAA (Lecture d)

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What is the Internet?• According to Wikipedia:

– “The Internet is a global system of interconnected computer networks that use the standard Internet Protocol Suite (TCP/IP) to serve billions of users worldwide.” (Wikipedia, 2010)

– The hardware that makes up the Internet is cabling, routers, switches, servers, and computers that host documents, audio, video, and others.

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What is the Internet (continued)• In other words, the Internet is a large network made up

of many smaller networks:– Computers connect to the Internet via an ISP

(Internet Service Provider) such as AT&T, Bell South, CenturyLink™, Verizon, and others

Visualization of the various routes through a portion of the InternetFrom “The Opte Project”

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(The Opte Project , c 2007, CC BY 2.5).

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The Origins of the Internet• The Internet has its roots in the US

Government’s desire to still be able to communicate, even in the event of a nuclear strike. ARPANET: Advanced Research Projects Agency

Network• The original Internet consisted of four computer

(servers) operating at UCLA; UC-SB; Stanford (SRI International); and the Univ. of Utah in 1969

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The Internet Today

• The world quickly saw its benefits and the Internet continued to grow, especially in the mid- 1990s In 1995, approximately 16 million people were using

the Internet Today, more than 1.8 billion people use the Internet

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The Internet Spawns the World Wide Web

• They are not the same thing!• The WWW is often referred to as the “Web” • According to Wikipedia:

“The Web is one of the services that runs on the Internet. It is a collection of interconnected documents and other resources, linked by hyperlinks and URLs.”

• A URL (uniform resource locator) is an address typed into a browser’s address line, such as www.whitehouse.gov

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Who Created the Web?• British scientist Tim Berners-Lee created the

WWW in 1989 by introducing a Web browser and Web page coding

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(Bojārs, U., 2005, CC BY 2.5)

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How Does the Web Work?• A browser is a software program that lets the

user interact with the Web by facilitating connection to other Web servers over the Internet

• The browser uses HTTP to communicate with Web servers to get Web page content

• The Web server sends HTML coding back to the browser, which translates the HTML coding for display on a monitor

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HTML - The Language of the Web• Web pages are text files written in the HTML

programming language• HTML example for a simple Web page

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2.1 Figure: Diagram of an HTML example for a simple Web page. (PD-US, 2010)

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The World’s First Web Server• This NeXT Computer was used by Sir Tim

Berners-Lee at CERN and became the world's first Web server

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(User: CoolCeaser, 2005, CC BY 3.0)

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Who Owns the Web?• No entity owns the Internet, but people and

organizations own the devices that connect to the Internet and form the WWW For example, Google’s experience in China(Wikipedia Web page entitled, Internet Censorship in the People’s

Republic of China)

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Standardized Communications

• Internet protocols are a global standard, ensuring interoperability between hardware and software devices

• Protocols such as HTTP allow any browser to talk to any Web server TCP/IP transports HTTP across the Internet for

delivery to its destination

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Internet Addressing Basics

• All Internet communication uses IP addressing• The Internet expects each communicating

device (known as a host) to possess an Internet Protocol (IP) address and subnet mask, which is a group of numbers in the format of: IP address: 192.168.10.1 Subnet mask: 255.255.255.0

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Internet Addressing Basics (continued)

• This host is in the 192.168.10.x network• This network can legally have addresses in the

range of 192.168.10.1 through 192.168.10.254• Networking devices and software use

192.168.10.0 and 192.168.10.255 for routing and communication

• Valid numbers are in the range of 0-255

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How to Obtain an IP Address

• Some IP addresses can be purchased or leased and used by the owner of that IP address or IP address range Referred to as public IP addresses Most IP addresses are public addresses

• Other IP addresses can be used by anyone• Referred to as private IP addresses Examples include 10.0.0.0, 172.16.31.0, and 192.168.0.0 IP addressing is beyond the scope of this unit

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Introducing Domain Names

• The Internet supports the use of domain names Imagine trying to navigate the Internet using IP

addresses and not names!• Since people remember names better than

numbers, the domain naming system (DNS) was created

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DNS & IP Work Well Together• DNS maps an IP address to a domain name• When you visit http://www.whitehouse.gov, your

computer must first figure out this Web site’s IP address One IP address for this site is 65.126.84.121.

This Web site is probably associated with many IP addresses

• Domain name resolution is accomplished through the use of DNS servers, which are located throughout the world

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DNS & IP Work Well Together (continued)

• All domain names are mapped to an IP address and stored on global and privately-owned DNS servers

• Global DNS servers are known as “root servers” and work together to map the globe’s names to their IP addresses

• When your browser learns the destination site’s IP address from the DNS server, communication begins!

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What is a Domain Name?• People and organizations can purchase a domain name

from ICANN• According to Wikipedia:

• “A domain name is an identification label that defines a realm of administrative autonomy, authority, or control on the Internet, based on the Domain Name System (DNS).” (Wikipedia, 2010)

• Domain names consist of three pieces:• The domain name, www.whitehouse.gov, indicates a

government site with the purchased domain name of “whitehouse,” found on the WWW

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Connecting to the Internet

• Devices commonly connect to the Internet via dial-up, broadband, Wi-Fi, satellite, and 3G Dial-up–copper phone lines connect to an ISP’s

modem. Limited to a speed of 56 Kbps The slowest connection type!

Broadband–higher quality copper phone lines, coaxial cable, or fiber optic connection type Faster than dial-up and in the approximate range of 768

Kbps and higher

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Connecting to the Internet (continued)

• Wi-Fi–wireless (radio frequency) connection type. Wi-Fi refers to the IEEE 802.11 standard governing

wireless technologies Typically used to connect laptops to WAPs. The WAP

is connected to the wired network to gain access to the Internet

Also used extensively by hotels and airports Wireless speeds range from 1 Mbps to 200+ Mbps,

depending on a variety of factors

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Connecting to the Internet (continued)

• Satellite–Connection to a ground satellite dish (antennae) and the satellite relays signals to a satellite orbiting the earth. Then the orbiting satellite relays the signal to another ground satellite dish Can be somewhat slow because of the time it takes to

make a round trip. The loss of speed is known as “latency.”

• 3G and 4G – The 3rd and 4th Generation of standards governing mobile telecommunications Speeds range from 2 Mbps to 28 Mbps.

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Internet and the World Wide WebSummary – Lecture a

• The Internet is a global system of interconnected networks

• The World Wide Web functions within the Internet and is made up of HTML Web pages and linked documents, which are stored on Web servers

• Internet communications are standardized around the IP protocol

• An IP address can be leased from an ISP

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Internet and the World Wide WebSummary – Lecture a

• The Internet relies on DNS to translate, or resolve a domain name to an IP address

• Computers connect to the Internet through the services provided by ISPs

• ISPs provide access to the Internet via dial-up, broadband, Wi-Fi, satellite, and 3G connections

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Internet and the World Wide WebReferences – Lecture a

References• Barretto, M. The count reached 1 Billion Internet Users Worldwide. [Online]. 2009, January 27; [cited 10 July

2010]; Available from: http://lab.77agency.com/marketing-analysis/the-count-reached-1-billion-internet-users-worldwide-1069/ .

• Domain name. Wikipedia [free encyclopedia on the Internet]. 2010 July 10; [cited 12 July 2010]; Available from: http://en.wikipedia.org/wiki/Domain_name.

• Evans A, Martin K, Poatsey MA. Chapter 1: Why Computers Matter to You. In: Technology in Action: Complete. 7th ed. New Jersey: Prentice Hall; 2010.

• Internet. Wikipedia [free encyclopedia on the Internet]. 2010 July 10; [cited 10 July 2010]; Available from: http://en.wikipedia.org/wiki/Internet.

• Internet censorship in the People's Republic of China. Wikipedia [free encyclopedia on the Internet]. 2010 July 11; [cited 12 July 2010]; Available from: http://en.wikipedia.org/wiki/Internet_censorship_in_the_People%27s_Republic_of_China.

• Internet World Stats. Internet Usage Statistics. 2009 December 31; [cited 10 July 2010]; Available from: http://www.internetworldstats.com/stats.htm.

• Parsons JJ, Oja D. Chapter 1: Computers and Digital Basics. In: New Perspectives on Computer Concepts 2011: Comprehensive. 13th ed. Boston: Course Technology; 2010.

• Shelley GB, Vermaat ME. Chapter 1: Introduction to Computers. In: Discovering Computers 2011: Introductory. 1st ed. Boston: Course Technology; 2010.

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Internet and the World Wide WebReferences – Lecture a

References• Tim Berners-Lee. Wikipedia [free encyclopedia on the Internet]. 2010 June 10; [cited 12 July 2010]; Available

from: http://en.wikipedia.org/wiki/Sir_Tim_Berners-Lee. • Web search engine. Wikipedia [free encyclopedia on the Internet]. 2010 July 11; [cited 12 July 2010]; Available

from: http://en.wikipedia.org/wiki/Web_search_engine. • World Wide Web. Wikipedia [free encyclopedia on the Internet]. 2010 July 12; [cited 12 July 2010]; Available

from: http://en.wikipedia.org/wiki/World_Wide_Web.

Charts, Tables, Figures• 2.1 Figure: Diagram of an HTML example for a simple Web page. (PD-US, 2010) .

Images• Slide 4: The Opte Project [image on the Internet]. The Opte Project (c2007). Accessed Jan 2012 from:

http://en.wikipedia.org/wiki/File:Internet_map_1024.jpg. Attribution 2.5 Generic (CC BY 2.5). • Slide 8: Tim Berners-Lee [image on the Internet]. (c2005). Accessed Jan 2012 from:

http://en.wikipedia.org/wiki/Sir_Tim_Berners-Lee. Attribution 2.5 Generic (CC BY 2.0).• Slide 11: Photo of the World’s First Web Server [image on the Internet]. User:Coolcaesar (c2005). Accessed Jan

2012 from: http://en.wikipedia.org/wiki/File:First_Web_Server.jpg. Attribution 3.0 Generic (CC BY 3.0).

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