Kip Becker, Ph.D. Boston University

Introduction to the World Wide Web

[email protected] HTTP:// WWW.BU.EDU/GOGLOBAL WHAT ARE SOME NEW ECONOMYCONCEPTS

 Large is no longer scary  Consumers Rule  Information cost low  Information Available  Compete in real time rather than in “cycle time”  Operate in a world characterized by low barriers to entry, near-zero variable costs of operation and shifting competition ALL ABOUT - ANYWHERE –ANYTIME “THE EVERYTHING NET” Productivity in Goods and Services 1960 - 94 Will the increase service productivity ? (Annual Index of output per Person – Hour, 1960=100)

Ratio Scale 300 280 260 Commercial Goods Sector 240 220 200 180 160 Commercial Services Sector 140 120 100

1960 1964 1967 1969 1972 1977 1980 1983 1986 1990 1974 WHAT YOU ARE LOOKING AT IS THE WORLD WIDE WEB AS IT WAS IN EARLY STATES. IT IS PRIVATE AND , AS YOU CAN SEE, VERY SMALL

 BUT THIS IS NOT THE BEGINNING

 SO LET’S EXPLORE THE HISTORY OF THIS AMAZING INVENTION THE INTERNET SO LET ME PROVIDE YOU WITH A VERY BRIEF HISTORY

• Internet’s beginnings traced to memos written in 1962 MIT’s Joseph Carl Robnett Licklider outlining the galactic networking concept

• Great advances made in network technology 1960s WERE NEEDED TO GET IDEAS MOVING

•HAD TO FIND WAYS To connect computers &permit transfer of information locally,

•organizations installed

•Local Area Networks. • then connected LANs to WANs

•BUT ---- •LAN technology were limited in functions EARLY CONNECTIONS 1. A global networked environment is known as the Internet 2. A counterpart within organizations, is called a: Intranet 3. An extranet extends intranets so that they can be accessed by business partners.

•To allow computers and networks separated by larger distance to communicate

•GOVERNMENT GOT INTERESTED AND FUNDED

ARPA (Advanced Research Projects Agency) TO DEVELOP a Wide Area Network (WAN) the ARPANET WHY CARE? WHY INVENT WEB ?) TO ANSWER THAT QUESTION WE HAVE TO GO BACK AND ASK •What was going on in 50s 60s? great communist threat ! •Production moved around auto plants, manufacturing whole idea was “one bomb” BUT INFORMATION NOT SAFE !

BANKING INFO, TAXES, SOCIAL SECURITY, CITENSHIP LOTS OF UNFORMATION GOVERNENT FUNDS ARPANET FOR GOVERNMENT USE  1989–1991: Web “invented” - Tim Berners-Lee at CERN 1993CERN e World Wide Web was free for everyone to use and develop, no fees 1993: Marc Andreesen /Others at NCSA create Mosaic, Web browser with GUI that runs on Windows, Macintosh, or  1994: Andreessen, Jim Clark Netscape; first commercial Web browser, Netscape Navigator  August 1995: Microsoft introduces Internet Explorer, its version of Web browser

Lets take a look at some of the early players THE WEB PROGRESSES  1988: First major malicious internet-based attack  major Internet worms"The ", it was written by Robert Tappan Morris major interruptions large parts of Internet  1995: Commercialization of the internet  considered year web became commercialized. First, SSL (Secure Sockets Layer) encryption Netscape, safer to conduct financial transactions (like credit card payments) online. first sale on "Echo Bay" was made that year. Echo Bay later became eBay. Amazon.com also started in 1995, No profit 2001  1995, Federal Networking Council (FNC) "Internet" refers to the global information system (i) logically linked together by globally unique address space based on Internet Protocol (IP)

 (ii) able support communications using the Transmission Control Protocol/Internet Protocol (TCP/IP)

 (iii) uses or makes accessible high level services layered on the communications and related infrastructure described herein. CONNECTIONS: NETWORK OF NETWORKS

 ISPs – INTERNET SERVICE PROVIDERS  NAPs – NETWORK ACCESS POINTS/ PACIFIC BELL NAP IN SANFRANCISCO & AMERITEC NAP CHICAGO  NSPs – “BACKBONE” NETWORK SERVICE PROVIDERS\ MCI, PSINET ETC.

HERE IS THE “OPEN ACCESS” DEBATE message sent on

YOU ISP

NAP NAP NSP - BACKBONE HARD/SOFT WARE Characteristics allow shared 1. Unique identificationaccess of dataeach of millions of computers - thousands networks.. Important each computer be uniquely identified Internet Protocol(IP) address. 198.108.95.145 2. Human-friendly addressing ↑ Domain Name System(DNS) gave address recognizable letters & words instead of IP address. http://www.bu.edu/GoGlobal 3. Packet Switching Remedy delays associated unequally sized data transfers, instead of transferring files in their entirety, whole files broken into data packets before transferred over network 4. Routing Dedicated, special-purpose computers which serve as an intermediary between networks. Route packets efficiently through networks and are building blocks of the internet. Packets used TCP software insures safe delivery of packets

ONE of MOST IMPORTANT PROTOCOLS TCP/IP Solves the global internetworking problem

• Transmission Control Protocol (TCP) – Ensures that 2 computers can communicate with one another in a reliable fashion Prevents loss of data ckecs packets Eliminates duplicate

• Internet Protocol (IP) • packets are labeled with the addresses of the sending and receiving computers

Sends confirmation received /not Retransmitted Error-free communication

Packet Switching

 Slices digital messages into packets

 Sends packets along different communication paths as they become available

 Reassembles packets once they arrive at destination

 Uses routers – Special purpose computers that interconnect the computer networks that make up the Internet and route packets – Routing algorithms ensure packets take the best available path toward their destination

 Less expensive, wasteful than circuit-switching Packet Switching

Figure 3.3, Page 132

Slide 3-19 RUNNING OUT OF V4 ADDRESSES