Transcript The Internet - Computer Information Science

THE INTERNET
• Began as a U.S Department of Defense
network to link scientists and university
professors around the world.
• No individual can connect directly to the Net,
he can access it through an Internet Service
Provider.
• INTERNET SERVICE PROVIDER (ISP):
organization connected permanently to the
internet, leases temporary connections to
subscribers.
• No one owns it.
• I has no formal management organization.
THE INTERNET
• As a creation of the Defense Department for
sharing research data, this lack of
centralization made it less vulnerable to
wartime or terrorist attacks.
• To join the Internet, an existing network
needs only to pay a small registration fee and
agree to certain standards based on the
TCP/IP reference model.
THE INTERNET
• Costs are low because the internet owns
nothing and so has no costs to offset.
• Each organization pays for its own networks
and its own telephone bills, however those
costs usually are independent of the Internet.
• Regional Internet companies have been
established to which member networks
forward all transmissions.
• These Internet companies route and forward
all traffic, and the cost is still only that of a
local telephone call.
THE INTERNET
• The Internet is based on the Client/server
technology.
• Individuals using the Net control what they do
through client applications such as Web
browser software.
• All the data, including e-mail message and
Web pages are stored on servers.
• A client uses the Internet to request
information from a particular Web server on a
distant computer, and the server sends the
requested information back to the client via
the Internet.
THE INTERNET
• Web server software receives requests for Web
pages from the client and accesses the Web pages
from the disk where they are stored.
• Web servers can also access other information from
an organization’s internal information system
applications and their associated databases and
return that information to the client in the form of Web
pages if desired.
• Specialized middleware, including application servers
and custom programs, is used to manage the
interaction between the Web server and the
organization’s internal information systems for
processing orders, tracking inventory, etc.
INTERNET CAPABILITIES
• E -MAIL: person -to-person messaging; document
sharing
• USERNET NEWSGROUPS: electronic bulletin
boards for discussion groups
• LISTSERVs: e-mail list servers for discussion
groups
• CHATTING: interactive conversations
• TELNET: log on one computer, work on another
• FTP: transfer files from computer to computer
• GOPHERS: use menus to locate text material
INTERNET CAPABILITIES
• ARCHIE: search database for files to download
• VERONICA: speeds searching gopher sites by
using keywords
• WIDE AREA INFORMATION SERVICE (WAIS):
locates files using key words
• WORLD WIDE WEB: retrieve, format, display
information (text, audio, graphics, video) using
hypertext links
INTERNET ADDRESS
[email protected]
INDIVIDUAL OR
ORGANIZATION NAME
HOST
COMPUTER
FUNCTION
LOCATION
DOMAIN NAME
INTERNET TERMS
• HOME PAGE: WWW screen display
welcomes user to organization’s
page
• WEBMASTER: person in charge of
Web site
• UNIFORM RESOURCE LOCATOR
(URL): address of specific Internet
resource
INTERNET TERMS
• HYPERTEXT TRANSPORT PROTOCOL
(http): communications standard (sets of
rules) used to transfer Web pages.HTTP
defines how messages are formatted and
transmitted and what actions Web servers
and browsers should take in response to
various commands.
• HYPERTEXT MARKUP LANGUAGE
(HTML): popular programming language
for creating Web sites
SURFING THE NET
• SEARCH ENGINE: tool for locating
specific sites or information on
WWW
• “PUSH” TECHNOLOGY: server
streams Web page content to a Web
browser
• HYPERLINK: spot on screen, when
clicked shifts to a new page or site
“Push” Technology
• Instead of surfing the Web, users can have the
information they are interested is delivered
automatically to their desktops through “push’
technology.
• A computer broadcasts information of interest directly
to the user, rather than having the user “pull’ content
from Web sites.
• “Push” comes from server push, a term used to
describe the streaming of Web page contents from a
Web server to a Web browser
• Special client software allows the user to
specify the categories of information he wants
to receive and how often this information
should be updated.
“Push” Technology
• Push program will notify the user by sending email, playing a sound, displaying an icon on
the desktop, sending full article or Web pages,
or displaying headlines on screen saver.
• Examples:
• Fruit of the Loom is using Pointcast push
technology to alert managers to updated
inventory information stored on its IBM AS/400
intranet Web server.
• Lufthansa uses the BackWeb push delivery
service to alert customers to fare discount.
INTRANET
• INTERNAL NETWORK: A simple intranet can
be created by linking a client computer with Web
browser to a computer with Web server software
via a TCP/IP network
• Intranet software technology is same as
that of the WWW TECHNOLOGY.
• FIREWALL: Security System (consists of
hardware and software placed between an
organization’s internal network and an external
network, including the Internet) to Prevent
Invasion of Private Networks
• Overcomes computer platform differences.
• Often installed on existing network infrastructure.
EXTRANET
Allows authorized users outside
organization to use its Intranet:
• Customers
• Business partners
• Vendors
EXTRANET
DATABASES
CUSTOMER
SUPPLIER
INTERNET
FIREWALL
SERVER
BUSINESS
PARTNER
CLIENTS
INTERNET BENEFITS
•
•
•
•
•
•
Global connectivity
Reduced communications cost
Lower transaction costs
Reduced agency costs
Interactivity, flexibility, customization
Accelerated knowledge
Components of an Internet server
SMTP
FTP
DNS
Client
Access
WAIS/
RDBFE
WWW
Server
Authorizing
Tools
Back/End Database
Network TCP/IP Stack
Network Operating system
Server Box
Internet Interface
Firewall/Router
Internet Service Provider
Components of an Internet server
SMTP: The Simple Mail Transfer Protocol utility translates between local and Internet mail
formats, allowing clients to send/receive Internet e-mail.
FTP: The File Transfer Protocol utility enables file transfers to and from the server.
DNS: The Domain Name Serving Utility maps numerical Internet machine addresses
(161.362.456.567) to alphabetic names (systems.compaq.com).
Client Access: The Client Access software allows local clients to use the Internet
(Web, FTP, etc.) over the existing network.
WAIS/RDBFE: The Wide Area Information Service and Relational Database Front End
Software allows Web site guests to access document database without requiring HTML
encoding beforehand. WAIS is the most thorough way to locate a specific file, however, you
have to know the name of the databases you want to search.
WWW Server: The WWW Server Software serves Web pages to guests and helps to
administrate the Web site.
Authoring Tools: Authoring Tools create the pages that appear on the Web site.
Components of an Internet server
Back/End Database: The Back/End Database is an Oracle, Sybase, or Back Office
database that contains content served to the Web via the RDBFE and WWW Server
Network TCP/IP: The TCP/IP stack allows the NOS to communicate via the Internet
protocol in addition to its native protocol.
Network Operating System: The Network Operating System is UNIX, Netware, or NT
Server Box: The server Box houses the CPU, disks, and Ethernet I/O hardware.
Internet Interface: The Internet Interface is a WAN card that connects the server to
the leased line provided by the Internet Service Provider (ISP). These cards can be
Installed in a separate firewall/router box or on the server itself.
Firewall/Router: The Firewall/Router sorts and filters data passing to and from the Internet.
This functionality is performed by software either installed on the server itself or on a
separate box.
Internet Service Provider: The Internet Service Provider provides an Ip address,
works through the local telephone company to arrange for a leased line, and provides
installation and administration consulting services.