History of the Internetand Internet Basics

AGED 4143

Electronic Communications

in Agriculture

History

• (1969) The U.S. DOD wanted a non-centralized network over phone lines that would survive power outages (ARPANet -- Advanced Research Projects Agency Network)– J.C.R. Licklider was the primary developer– He informally referred his idea as the “intergalactic

network,” (later reduced to “internet”)– Defense research programs at UCLA and Stanford

were the first two nodes

History

• (1972) NCSC developed telnet, allowing for remote log in

• (1973) FTP was introduced, allowing easy transfer of files among remote computers

• (1977-83) A standard method of packaging messages was developed (TCP/IP-Transmission Control Protocol/ Internet Protocol), and more supercomputers (nodes) were added

History

• (1983) MILNET split from ARPANET• (1983) Desktop computers with UNIX

operating systems appeared• (1985) The NSF got involved by linking a

major network (NSFNET) to the internet for use by academic researchers

History

1993 NSFNET Backbone

History

• (1989) The backbone network was upgraded with help from IBM to "T1" (1.5 million bits of data per second, or about 50 pages of text per second)

• 1990 ARPANET was dissolved• 1993 NSFNET was upgraded to “T3”• (1994) Internet use exploded due to the advent

of the the University of Minnesota’s Gopher Server and CERN’s World Wide Web.

History

History

• The Web was a project developed by CERN (Conseil Européen pour la Recherche Nucléaire), a European organization energy research

• The Web was built with the use of hypertext in mind (term coined in 1968)

• (1979) Charles Goldfarb invented SGML, which led to HTML (Tim Berners-Lee)

History

• (1994) Netscape was founded; Web servers on the internet grew from 250 to 2500 in one year

• (1993-94) Web browsers Mosiac and Netscape Navigator were introduced

• (1995) Servers grew to 73,500 in one year

• (1998) 72.6 million Americans had internet access

History

• WYSIWYG, icon-driven programming is commonplace

• Real-time and interactive communication is prevalent, with the advent of CGI programming and video and audio streaming

• 64% of Americans 12 and older used the internet in 2001

History

• Projections:– 2005: 300 million people will be connected

How the Web Works

• http://www.howstuffworks.com/web-server1.htm

How the Web Works

• http://www.howstuffworks.com/web-server1.htm

• The Web is only a part of the internet

• Some of the “servers” connected to the internet are “web servers”– Special software to handle http (hypertext

transfer protocol)

How the Web Works

• Servers have their own domain name, which is a human conversion of an IP (internet protocol) address– E.g., www.howstuffworks.com = 209.116.69.66

• The domain name is a part of the URL (uniform resource locator), which is the web address

How the Web Works

• Servers have their own domain name, which is a human conversion of an IP (internet protocol) address– E.g., www.howstuffworks.com = 209.116.69.66

• The domain name is a part of the URL (uniform resource locator), which is the web address– Web browsers request documents from web

servers using the URL

How the Web Works

• URLs contain the following elements– access method (usually hypertext transfer protocol -- http://) – location or domain name (www.uark.edu) – directories and HTML file (/depts/aeedhp/index.html)

• So, the address for the AEED home page ishttp://www.uark.edu/depts/aeedhp/index.html

• Organizations like InterNIC, working with the World Trade Organization, register domain names for $35 and up

How the Web Works

• Modems convert digital information to analog information that can travel over the physical lines that make up the internet

• These lines include phone lines (twisted pair and optical fiber), coaxial cable, satellite airwaves, then they convert incoming analog signals back to digital

• Digital conversion takes time and slows download speeds

How the Web Works

• Information requested by the browser on your lab computer from a Web server in India, for example, probably follows this route:

• Server in India – Regional network in Asia – backbone network – regional network in U.S. – U of A server – PC in computer lab

• All the files related to a Web site are stored in a directory on a web server (usually owned by an ISP/OSP or by a large company or organization)

How the Web Works

• Each web site is a collection of pages linked by hypertext that can be read with a web browser, like Netscape Navigator or Microsoft Internet Explorer

• The browser reads the HTML tags for the page requested and represents them on the monitor as graphics and text.

• When you “open” a web site, your computer downloads each individual file associated with each page to its RAM and displays the visual images on your monitor