Transcript - SCT Web Site - Eastern Mediterranean University

Eastern Mediterranean University
School of Computing and Technology
Department of Information Technology
ITEC229
Client-Side Internet and Web Programming
Introduction to Internet
and World Wide Web
CHAPTER 1
Prepared by: R. Kansoy
LOGO
Contents
1.1 What is Internet?
1.2 History and Development of the Internet
1.3 Internet Standards & Coordination
1.4 Anatomy of the Internet
1.5 Bacis Internet Protocols
1.6 Technologies/Tools of the Internet
1.7 World Wide Web
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1.1 What is Internet?
 The Internet, sometimes called simply "the Net," is a
worldwide system of computer networks - a network of
networks in which users at any one computer can, if they
have permission, get information from any other computer
(and sometimes talk directly to users at other computers).
 Originally the Internet served to interconnect laboratories
engaged in government research, and since 1994 it has
been expanded to serve millions of users and a multitude
of purposes in all parts of the world.
 In a matter of very few years, the Internet has
consolidated itself as a very powerful platform that has
changed the way we do business, and the way we
communicate.
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1.1 What is Internet?
 The Internet, as no other communication medium, has
given an International or, if you prefer, a "Globalized"
dimension to the world.
 Internet has become the Universal source of information
for millions of people, at home, at school, and at work.
 Internet is actually the most democratic of all the mass
media. With a very low investment, anyone can have a web
page in Internet.
 This way, almost any business can reach a very large
market, directly, fast and economically, no matter the size
or location of the business.
 With a very low investment, almost anybody that can read
and write can have access to the World Wide Web.
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1.2 History and Development of the Internet
 It was conceived by the Advanced Research Projects Agency
(ARPA) of the U.S. government in 1969 and was first known as
the ARPANet.
 The original aim was to create a network that would allow users of
a research computer at one university to be able to "talk to"
research computers at other universities.
 In time, ARPANET computers were installed at every university
in the United States that had defense related funding.
 Gradually, the Internet had gone from a military pipeline to a
communications tool for scientists.
 As more scholars came online, the administration of the system
transferred from ARPA to the National Science Foundation.
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1.2 History and Development of the Internet
Brief History of the Internet
 1960 - US government seeks nuclear war proof
communications, briefs project to APRA
 1968 - DARPA (Defense Advanced Research Projects
Agency) contracts with BBN (Bolt, Beranek &
Newman) to create ARPAnet
 1969 - Birth of Internet. Universities and researches
connected to ARPAnet.
 1970 - First five nodes:





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UCLA
Stanford
UC Santa Barbara
University of Utah, and
BBN
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1.2 History and Development of the Internet
 ARPANET
 Implemented in late 1960’s by ARPA (Advanced Research
Projects Agency of DOD)
 Networked computer systems of a dozen universities and
institutions with 56KB communications lines
 Grandparent of today’s Internet
 Intended to allow computers to be shared
 Became clear that key benefit was allowing fast communication
between researchers – electronic-mail (email)
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1.2 History and Development of the Internet
Brief History of the Internet
 1971 - Ray Tomlinson creates first network email application.
 E-mail - a program to send messages across a
distributed network.
 1972 – Telnet - Computers can connect more freely and easily
 1973 – FTP - computers send and receive data.
 1974 - TCP specification by Vint Cerf
 1977 - ARPAnet engineers realise the network is going to grow
beyond expectations
 1983 - ARPAnet switched NCP to TCP/IP
 1984 - Domain Name System (DNS) was introduced.
 1989 - Tim Berners-Lee proposes a new set of Internet protocols
 1991 - World-Wide Web - developed released by CERN; within the
UK academic network.
 1992/93 - Mosaic/Netscape - User Friendly Graphical Front
 1995 - US government releases Internet for commercial use
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1.3 Internet Standards & Coordination
 ICANN - The Internet Corporation for Assigned
Numbers & Names
 Non-profit organization
 Main function is to coordinate the assignment of:
• Internet domain names
• IP address numbers
• Protocol parameters
• Protocol port numbers.
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1.3 Internet Standards & Coordination
 Internet Engineering Task Force (IETF)
 http://www.ietf.org/
 Founded 1986
 Request For Comments (RFC) at
http://www.ietf.org/rfc.html
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1.3 Internet Standards & Coordination
 W3C – World Wide Web Consortium
 Develops recommendations and prototype
technologies related to the Web
 Produces specifications, called
Recommendations, in an effort to
standardize web technologies
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1.4 Anatomy of the Internet
 Internet Backbone
A high capacity communication link that carries data
gathered from smaller links that interconnect with it.
 NAP – Network
Access Point
Access points or
junctions to the
Internet Backbone
in major cities.
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1.4 Anatomy of the Internet
 Client/Server can describe a relationship between two
computer programs – the "client" and the "server".
 Client
 requests some type of service (such as a file or database
access) from the server.
 Server
 fulfills the request and transmits the results to the client
over a network
 The Internet Client/Server Model
 Client -- Web Browser
 Server -- Web Server
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1.4 Anatomy of the Internet
 Web Client
 Connected to the Internet when needed
 Usually runs web browser (client) software such as
Internet Explorer or Netscape
 Uses HTTP (Hypertext Transfer Protocol)
 Connect to a web server using URL information
 Requests web pages from server
 Receives web pages and files from server
 Display the formatted information
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1.4 Anatomy of the Internet
 Web Server
 Continually connected to the Internet
 Runs web server software (such as Apache or Internet
Information Server)
 Uses HTTP (Hypertext Transfer Protocol)
 Receives request for the web page
 Responds to request and transmits status code, web page, and
associated files
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1.5 Basic Internet Protocols
 Protocols : rules that describe the methods used for
clients and servers to communicate with each other
over a network.
 There is no single protocol that makes the Internet and
Web work. A number of protocols with specific
functions are needed.
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1.5 Basic Internet Protocols
 FTP (File Transfer Protocol)
 A set of rules that allow files to be exchanged between computers on the
Internet.
 Web developers commonly use FTP to transfer web page files from their
computers to web servers.
 FTP is also used to download programs and files from other servers to
individual computers.
 E-mail Protocols
 Sending E-mail
• SMTP Simple Mail Transfer Protocol
 Receiving E-mail
• POP (POP3) Post Office Protocol
• IMAP Internet Mail Access Protocol
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1.5 Basic Internet Protocols
 Transmission Control Protocol/Internet Protocol
TCP/IP
 TCP/IP has been adopted as the official communication
protocol of the Internet.
 TCP and IP have different functions that work together to
ensure reliable communication over the Internet.
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1.5 Basic Internet Protocols
 Transmission Control Protocol (TCP)
 Purpose is to ensure the integrity of communication
 Breaks files and messages into individual units called
packets
 Internet Protocol (IP)
 A set of rules that controls how data is sent between
computers on the Internet.
 IP routes a packet to the correct destination address.
 The packet gets successively forwarded to the next closest
router (a hardware device designed to move network
traffic) until it reaches its destination.
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1.5 Basic Internet Protocols
 HTTP - Hypertext Transfer Protocol
 A set of rules for exchanging files such as text, graphic images, sound,
video, and other multimedia files on the Web.
HTTP Request
HTTP Response
 Web browsers send HTTP requests for web pages and their associated
files.
 Web servers send HTTP responses back to the web browsers.
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1.6 Technologies/Tools of the Internet
 World Wide Web: a branch of the Internet that provides
access to hyperlinked information.
 E-mail: electronic message containing information sent
from one computer to another over networks.
 Listservs/mailing
lists:
a
facility
that
participation in ongoing discussions via e-mail.
allows
 Usenet Newsgroups and discussion groups: worldwide distributed system of online discussion groups in
which people continuously participate. Newsgroups allow
people with a common interest to subscribe to one or
more groups for posting, reading and replying to
electronic mail.
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1.6 Technologies/Tools of the Internet
 Internet Relay Chat and web chatting: having a
conversation with many people on a variety of topics in real
time. All the parties to the conversation are participating
simultaneously regardless of the time zone they are in.
 Channels: Channels on the web are a pre-selected
information source that can send information to your
computer automatically according to a predetermined
schedule.
 FTP: File Transfer Protocol allows you to copy files from one
computer connected to the Internet to another computer
connected to the Internet. It allows you to download
information, upload web pages and transfer information
between computers.
 Telnet: The Telnet protocol is an application that allows a
remote connection to another computer.
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1.6 Technologies/Tools of the Internet
 Intranet: are private networks that help an organization to
share information between departments, units and regions
across a network
 Internet Phone: allows one to put a number of calls on the
same line without sacrificing sound quality.
 Video Conferencing: allows you to chat with one or more
people in real time and/or to see live images as you speak
or type.
 Blogs: Blogs or web logs are personal web pages that
contain personal thoughts and links to other sites that are of
particular interest to a blog owner.
 Wikis: Wikis are collaborative websites where the
community participate in writing a publication, like an
encyclopaedia or a general purpose website.
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1.7 World Wide Web (WWW)
 Development of the Web
 1989-1991: Web invented by Tim Berners-Lee at
European Physics Laboratory (CERN).
Bill
Clinton
”When I took office,
only high energy
physicists
had ever heard of
what is called the
World Wide
Web... Now even my
cat has it's own
page.”
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 1993: Marc Andreesen and others at NCSA create
Mosaic, a Web browser with a graphical user interface
that could run on Windows, Macintosh, or Unix
computer.
 1994: Andreesen and Jim Clark found Netscape, and
create first commercial Web browser, Netscape
Navigator.
 August 1995: Microsoft introduces its version of Web
browser, Internet Explorer.
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1.7 World Wide Web (WWW)
 What is WWW?
 is a way of accessing information over the medium of the
Internet.
 is one of the major services of the internet who hosts
information of almost about anything one might like to
search for.
 computer network consisting of a collection of Internet
sites that offer text and graphics and sound, video and
animation resources through the hypertext transfer
protocol.
 The Web uses the HTTP protocol, only one of the languages
spoken over the Internet, to transmit data. Web services,
which use HTTP to allow applications to communicate in
order to exchange business logic, use the Web to share
information.
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 The Web also utilizes browsers, such as Internet
Explorer or Firefox, to access Web documents called Web
pages that are linked to each other via hyperlinks.
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1.7 World Wide Web (WWW)
 Web Browsers
 a programme used to locate, display, browse and view
information on a website.
 when you request a web page by entering the URL in
the location field of the browser, the browser contacts
the web server and asks for a copy of the page. The
browser displays the page when it arrives.
 a browser can be text based in which case you would
only be able to view web pages in text mode or could
have a graphical user interface in which case you would
be able to view the web page in graphical mode.
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1.7 World Wide Web (WWW)
 Web Addresses
 Each Web page has a unique address called the
Uniform Resource Locator (URL).
 The URL tells the computer how and where to
look for a document.
 Example: http://www.cnn.com/world/index.html
 The hypertext links are attached to Web
addresses.
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1.7 World Wide Web (WWW)
 Web Pages
 A Web page is a file on the Web.
 A Web site is a collection of Web pages maintained
by a college, government agency, company or
individual.
 A Web page is created by using a computer
language called Hypertext Markup Language
(HTML).
 HTML is a set of codes used to format Web pages
and create links.
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1.7 World Wide Web (WWW)
 Hypertext
 Web pages are hypertext documents.
 A hypertext document is one that contains
highlighted text or links that connect to other pages
on the Web.
 By clicking on the hypertext link you can
go to another Web page on the same
computer, or a Web page on a computer
across the world.
 The Web uses a protocol called Hypertext
Transfer Protocol (HTTP) to transfer
documents containing hypertext.
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 HTTP's job is similar to that of TCP/IP.
HTTP and TCP/IP, both protocols, or
standards, tell computers how to
communicate with each other.
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Introduction to Internet and
World Wide Web
END of CHAPTER 1
LOGO
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