Assignment 7


1. Go to http://www.w3.org and find an answer to this question:
What is the W3C World Wide Web Consortium. Find a simple explanation. Use your own words.

   The World Wide Web Consortium (W3C) provides an opportunity to share information and communicate with others about interoperable technologies such as specifications, guidelines, software, and tools to improve Web industry.


2. Find and write simple explanations for the following terms.

a. Cyberspace

   This is the "electronic" world as perceived on a computer screen, the term is often used in opposition to the "real" world. With Web-extensions like VRML and the Cyberspace Protocol, Virtual Reality will one day come to your home computer.

  (VRML: Virtual Reality Modeling Language. The term "VRML" had been coined by Dave Ragget at the 1st WWW Conference in Geneva, May 1994. VRML is proposed as a logical markup format for non-proprietary platform independent VR.)

b. download

   To transfer (data or programs) from a server or host computer to one's own computer or device.

c. upload

   To transfer (data or programs), usually from a peripheral computer or device to a central, often remote computer

d. GIF

  < graphics, file format> /gif/, occasionally /jif/ (GIF, GIF 89A) A standard for digitised images compressed with the LZW algorithm, defined in 1987 by CompuServe (CIS).

   Graphics Interchange Format and GIF are service marks of CompuServe Incorporated. This only affects use of GIF within Compuserve, and pass-through licensing for software to access them, it doesn't affect anyone else's use of GIF. A service mark used for a raster-based color graphics file format, often used on the World Wide Web to store graphics

e. JPG

  Joint Photographic Experts Group
   (JPEG) The original name of the committee that designed the standard image compression algorithm. JPEG is designed for compressing either full-colour or grey-scale digital images of "natural", real-world scenes. It does not work so well on non-realistic images, such as cartoons or line drawings. JPEG does not handle compression of black-and-white (1 bit-per-pixel) images or moving pictures. Standards for compressing those types of images are being worked on by other committees, named JBIG and MPEG.

f. PNG

  Portable Network Graphics
   /ping/ (PNG) An extensible file format for the lossless, portable, well-compressed storage of raster images. PNG provides a patent-free replacement for GIF and can also replace many common uses of TIFF. Indexed-colour, greyscale and truecolour images are supported, plus an optional alpha channel. Sample depths range from 1 to 16 bits. PNG is designed for on-line viewing applications, such as the World Wide Web, so it is fully streamable with a progressive display option. PNG is robust, providing both full file integrity checking and simple detection of common transmission errors. Also, PNG can store gamma correction and chromaticity data for improved colour matching on heterogeneous platforms

g. login (as a noun and a verb)

   (Or "log in", "log on", "logon") To start a session with a system, usually by giving a user name and password as a means of user authentication. The term is also used to mean the ability to access a service (also called an account), e.g. "Have you been given a login yet?" "Log in/on" is occasionally misused to refer to starting a session where no authorisation is involved, or to access where there is no session involved. E.g. "Log on to our Web site!" "login" is also the Unix program which reads and verifies a user's user name and password and starts an interactive session.

h. mailing lists (listserv and majordomo)

   (Often shortened in context to "list") An electronic mail address that is an alias which is expanded by a mail exploder to yield many other e-mail addresses. Some mailing lists are simple "reflectors", redirecting mail sent to them to the list of recipients. Others are filtered by humans or programs of varying degrees of sophistication; lists filtered by humans are said to be "moderated". The term is sometimes used, by extension, for the people who receive e-mail sent to such an address. Mailing lists are one of the primary forms of hacker interaction, along with Usenet. They predate Usenet, having originated with the first UUCP and ARPANET connections. They are often used for private information-sharing on topics that would be too specialised for or inappropriate to public Usenet groups. Mailing lists are easy to create and (unlike Usenet) don't tie up a significant amount of machine resources. Thus, they are often created temporarily by working groups, the members of which can then collaborate on a project without ever needing to meet face-to-face. >e.g. Listserv, Listproc, Majordomo.

i. newsgroups

1). What is USENET?

   Usenet encompasses government agencies, universities, high schools, businesses of all sizes, and home computers of all descriptions. In the beginning, not all Usenet hosts were on the Internet. As of early 1993, it hosted over 1200 newsgroups ("groups" for short) and an average of 40 megabytes (the equivalent of several thousand paper pages) of new technical articles, news, discussion, chatter, and flamage every day. >several web gateways such as Deja. Several web browsers include news readers and URLs beginning "news:" refer to Usenet newsgroups. Network News Transfer Protocol is a protocol used to transfer news articles between a news server and a news reader. The uucp protocol was sometimes used to transfer articles between servers, though this is probably rare now that most sites are on the Internet.

2) How is USENET different from our class Discussion Board?

j. packet switching

   A communications paradigm in which packets (messages or fragments of messages) are individually routed between nodes, with no previously established communication path. Packets are routed to their destination through the most expedient route (as determined by some routing algorithm). Not all packets travelling between the same two hosts, even those from a single message, will necessarily follow the same route. The destination computer reassembles the packets into their appropriate sequence. Packet switching is used to optimise the use of the bandwidth available in a network and to minimise the latency. X.25 is an international standard packet switching network. Also called connectionless. Opposite of circuit switched or connection-oriented. See also virtual circuit, wormhole routing.

k. router

   A device which forwards packets between networks. The forwarding decision is based on network layer information and routing tables, often constructed by routing protocols. Unix manual page: route(8). See also bridge, gateway, Exterior Gateway Protocol, Interior Gateway Protocol, flapping router