INTERNET

€ there is no actual Internet, there is a amalgam of thousands of independent networks
€ meganetwork, network of networks
€ other vast networks: UUCP (Unix-to-Unix CoPy), BITNET (Because It's Time Network), USENET (User's Network), FidoNet
€ Internet has over 5 million host servers: 2 million in US, approximately 700 000 in EU countries
€ approximately 30-60 million users
€ in theory, nobody controls Internet

How it all started?

€ at the beginning the whole sytem (services and interfaces) were developed by volunteers
€ 1960's the Cold War was being fought in research labs (federal spending).
€ by the late 1960's every major research center had a computer facility equipped with the lates technology
€ 1969 ARPANET (Advanced Research Projects Agency)
- four universities: Los Angeles, Santa Barbara, Stanford University, Salt Lake City
- TCP/IP (Transmission Control Protocol/Internet Protocol)
- packet switching
(€ other protocols: Point to Point Protocol(PPP), Serial Line Internet Protocol (SLIP)) € ARPA funded a study by the firm Bolt Beranek and Newman (BBN)
€ DEC (Digital Equipment Corporation): minicomputers - UNIX
€ UNIX was from the beginning an operating system that understood networking
€ toward the end of the 1970's networks were starting to pop up everywhere
€ the declining costs of computing and of long-distance communications (critical mass)
€ 1979 CSnet (Computer Science Research Network)
€ nowadays Internet is nearly everywhere, even the South Pole is connected
€ new generation of the Internet protocol is coming: IPv6 or IPng (next generation):
- a flow ID (some packets more timecritical than others)
- multicasting
- flexibility

€ the Internet has been in constant operation for more than 20 years and witnessed rapid and continual improvements in communications technology:
- ISDN (Integrated Services Digital Network)
uses the same twisted-pair wiring of Plain Old Telephone Service
telephone technology supporting cost-effective, higher-bandwidth Internet access
- deployment of ATM (Asynchronous Transfer Mode)
cell-relay protocol
small, fixed-size cells
"multimedia network"

Who is in charge?

€ Internet Society (ISOC)
- assigns IP addresses, domain names
- Internet Engineering Task Force (IETF) and Internet Architecture Board (IAB)
€ Internet is growing FAST: 9%-12% per month
€ from 1988 to 1994 4700 % growth in registered hosts
€ the commercial domains comprise more than a half of all Internet hosts

Demographics of the Internet

€ Graphic, Visualization & Usability (GVU) has done the four phase research about the WWW users
€ the 4th survey (October 1995 - November 1996):
- average age 31
- 30 % female - 70 % male
- the most common usage within enterprises (business-to-business)
- users are not shopping (mainly because of the security risks), but using Web for entertainment and work/research
- less and less "technology developers/pioneers", more "early adopters/seekers of technology"
- estimated average income $ 63 000
- 41.7 % married, 40.8 % single
- 78.4 % browses daily
- the biggest problem: the speed it takes to download and display content
- over the half of the respondents learned the basics of HTML under 3 hours

The main services:

€ the Internet allows users around the world to share a common set of applications residing on millions of computers:

E-mail

€ first used in ARPANET, e-mail protocol invented 1971
€ Internet e-mail standard include:
- Simple Mail Transfer Protocol (SMTP; the primary mail standard)
handles plain text, cannot send binary files
no inherent security
- Multipurpose Internet Mail Extension (MIME)
handles diverse object types
allows binary files to be included as attachments
some MIME-based e-mail systems display file attachments such as word processing documents and graphics
- Privacy Enhanced Mail (PEM)
standard for encrypted mail
uses public key cryptography to encrypt mail
- Extended SMTP
- Post Office Protocol (POP)
often used to support PC's, reducing PC connect time
user downloads mail to the local system and composes responses offline, then uploads return mail
€ X.400 standard is not based on TCP/IP like SMTP is, it's a OSI (Open Systems Interconnect) standard
- more complex
- highly reliable, more fully featured than Internet standards
- more used in Europe than in US
- one of the reasons for X.400 "popularity" is a sister standard X.500 which provides white pages and directory services

Telnet

€ one of the basic Internet applications, allows users on one system on the network to log-on to another on which they have an account
€ to Telnet (verb) (telnet computer_name)

Newsgroups (Usenet)

€ original idea by Steve Bellovin (University of North Carolina)
€ the function was to provide a network that would enable any user to submit an article that would be routed to all computers on the network

Seven main categories
comp computer-related discussion
news news about Usenet
rec recreation
sci science
soc sociological discussion
talk chit-chat
misc miscellaneous

Seven main categories
comp	computer-related discussion
news	news about Usenet
rec	recreation
sci	science
soc	sociological discussion
talk	chit-chat
misc	miscellaneous

Mailing lists

€ a usually automated system that allows people to send e-mail to one address, whereupon their message is copied and sent to all of the other subscribers to the mailing list

Talk

IRC (Internet Relay Chat)

€ Basically a huge multi-user live chat facility

FTP

€ accounts for the majority of traffic on the Internet
€ users are often invited to download trial copies of software using what is called "anonymous" FTP
€ normally WWW can be used

Archie

€ if there is a shareware utility whose location is uncertain, the search tool called Archie is very helpful
€ Archie severs poll FTP esrvers monthly to find out their contents and build a searchable index
€ Telneting is the easiest way to use Archie (use an e-mail address as the password)
€ of course, WWW is normally the easiest way of finding any resource

Gopher

€ a text-based series of menus that lead users around the Internet by selecting menu options
€ Gophers are easy to establish and easy to maintain

Veronica

€ Very Easy Rodent-Oriented Networkwide Index to Computerized Archives
€ search engine to do keyword searches of Gopher-based resources

WAIS (Wide Area Information System)

€ provides indexed searches, uses relevancy feedback to help narrow and focus a search
€ often accessed through Web or Gopher, because of the difficulty of its interface

Videoconferencing

€ still quite experimental and used in practice mainly by the academic and research community
€ because of the packet switching over the Internet videoconferencing is quite difficult - lots of delays
€ Cornell CU-SeeMe, developed 1991
€ Mbone
- uses multicast capable LAN's and dedicated routers that create a virtual network on top of the Internet

€ Videoconferencing Protocols:
- Protocol Independent Multicast (PIM)
- Distant Vector Multicast Routing (DVMRP)
- Real-Time Transport Protocol (RTTP)
- Streaming II (ST II)
- ReSerVation Protocol (RSVP)
- Multicasting Ponint-to-Point Protocol (MPPP)

MUD's (MultiUser Dimensions (Dungeons))

€ to date, the primary use of multiuser dimensions has been for role-playing fantasy games
€ players connect to MUD, talk amongst themselves, send messages to one another, fight monsters or one another, and possibly create new objects
€ most muds are currently text-based, but there are plans to go graphical too (MOO's = Multi-user Object-Oriented environments)
€ virtual classrooms?

The World Wide Web

€ created 1990 in CERN (the European Center for Nuclear Research) in Geneve, Switzerland by Tim Berners-Lee
€ originally designed as a method for physicists to share documents and communicate with other researches
€ easy-to-use interface (graphic)
€ based on hyperlinks
€ works on any hardware platform and using any protocol
€ provides a seamless, intuitive interface to data that may be both technologically and geographically diverse
€ ability to run other Internet applications without requiring knowledge of the command language or Unix
€ the initial page of any Web site is called a home page
€ hyperlinks point to otehr Web resources
€ Web resources are designated using a Uniform Resource Locator (URL), the first part of URL specifies the type of protocol (e.g. http, gopher, ftp), then a host name, a directory and a file name
€ the protocol underlying the Web, HTTP = HyperText Transport Protocol), is a superset of most protocols
€ each access is referred to as a hit
€ to access the Web, a browser is needed -- Netscape Navigator, Mosaic, Explorer etc. Any Web server can be accessed with any browser
€ there are also text-based browsers (Lynx), which cannot display graphics or underlind text, users select numbers to choose hyperlinks

€ also the Web is growing fast: 1993: 50 sites, 1995: 37 000 (outside the corporate firewalls)
€ traffic on the Web doubles every four months
€ the Web documents are coded in HyperText Mark-Up Language (HTML) -- determines a basic look of a Web page (where and in what format graphics appear)
€ a subset of a standard called Standard Generalized Mark-up Language (SGML)
€ the principle underlying HTML is that formatting should be separate from text, which is separated from presentation
€ authors mark basic ASCII text with a minimum of formatting commands called tags

The Browsers

€ Mosaic was created 1993 by National Center for Supercomputing Applications (NCSA) -- Marc Andreessen
€ Netscape Navigator created by 5 members of the original NCSA Mosaic team (incl. M. Andreessen) and Jim Clark (founder of Silicon Graphics, Inc.)
€ Netscape browsers account for 75 % of the Web's traffic
€ motto: if it is not available, invent it!

€ InterAp
€ WinTapestry
€ Internet Works (AOL)
€ Internet in a Box
etc.

Freeware Browsers:

€ Lynx
€ WinWeb
€ Cello

The Search Engines

€ AltaVista
€ Lycos
€ Yahoo
€ WebCrawler

€ very often the most popular sites have too much traffic and are difficult to reach
€ nowadays the most popular servers are to be mirrored, providing another server with the same information at a strategic point around the world

€ Cern is no more responsible, Tim Berners-Lee left CERN to found Web Consortium (W3C), headquartered at the Massachusetts Institute of Technology (MIT)
€ meanwhile in Europe, the European Commision transferred the responsibility form CERN to the French National Institute for Research in Computing and Automation (INRIA)