The Internet

(The History Channel)

(Straubhaar & LaRose)

History

• The internet is a global network of computer-based communication.

• The internet was first envisioned in the 1950s by MIT scientist J. C. R. Licklider.

• After the Soviet Union launched the Sputnik satellite in 1957, President Eisenhower established the Advanced Research Projects Agency (ARPA) to keep pace with Soviet space technology.

Development

• Queuing Theory– Leonard Kleinrock worked with queuing

theory to study how information arrives, remains, and leaves locations.

– Queuing theory works based on:• Demand Access: Having access to information

only at the time it is required.• Distributed Control: All nodes in a system share

control of information transmission.

Development

• Unlike telephones which rely on a system of “circuit switching,” the internet relies on a system of “packet switching” in which information may share avenues of transmission.– Circuit Switching: Dedicated lines of

communication– Packet Switching: Information is transmitted

through a network of avenues based on demand access and distributed control.

Development

• Inspired by an article authored by Claude Shannon (1952), Paul Baran sought to develop a packet switching method called “hot potato” routing.

Development

• “Hot Potato” packet switching:– Packets (pieces of a file) are assigned

headers (address & return address) and transmitted through a network connected by nodes which distribute them from place to place based on the availability of memory.

Development

• Computer scientist Bob Taylor devised a way to use a single terminal to access multiple computer mainframes.

• In 1969, Dr. Larry Roberts of ARPA created the ARPAnet by combining multiple computers into a single network through Interface Message Processors (IMPs) which could communicate with one another (see diagram on following slide).

Development

• Bob Metcalfe invented the “ethernet” capable of linking together a Local Area Network (LAN).

• Ray Tomlinson invented E-mail in 1971 by combining message files with mailbox files.

Development

• Vinton Cerf and Robert Kahn developed the protocols necessary to join networks into larger networks.– Internet Protocol (IP): Specifies how files are

broken into packets and how they are addressed.

– Transmission Control Protocol (TCP): Controls the movement of information from one network device to another through retransmission.

Development

• Networks are combined through “gateways” to form the internet as a network of networks.

Development

• In 1992, Congress passed a bill transferring the ARPAnet to the private sector.

• Tim Berners-Lee started the World Wide Web by developing Hypertext Markup Language (HTML) needed for linking files.

Development

• Mark Andreessen developed the first web browser, “Mosaic,” which was later marketed as “Netscape Navigator.”

How it Works

• Visiting a website:1. You enter an address (uniform resource

locator - URL) into your browser.

2. The address of the website is translated into the numerical IP (Internet Protocol) address of its server by the Domain Name Service (DNS) protocol and sent to the modem.

How it Works

• Visiting a website:3. The request is formatted in Hypertext Markup

Language (HTML) and routed through the modem to the Internet Service Provider (ISP).

4. The request arrives at the server which responds by deploying the webpage as a series of data packets which are assigned the Transmission Control Protocol (TCP) necessary for reconfiguration at your computer.

How it Works

5. The packets and TCP information are sent through various routers to your IP (Internet Protocol) address where the webpage is reassembled as an HTML file.

Sectors

• The Internet has several industry sectors:– Hardware: Computer manufacturing (e.g. Dell,

Gateway, Mac).– Software: Program manufacturing (e.g.

Microsoft, Adobe, Macromedia, Nuance)– Content Providers: Website manufacturing

(e.g. web designers)– Internet Service Providers: Provide

connection to the internet (e.g. AOL, MSN).

Content

• Electronic Publishing– (e.g. Online editions of newspapers.)

• Entertainment– (e.g. TV stations and movie websites.)

• Online Games– (e.g. The Sims, Halo, EverQuest)

• Portals

Implications

• The internet will absorb all previous media systems.– “Hardware,” such as television sets and radio

receivers already exist as applications (e.g. RealPlayer, Windows Media Player, QuickTime, WinAmp)

– Broadcast transmissions will be replaced or duplicated by webcast transmissions once the image quality of streaming video becomes equivalent with HDTV.