Data Communication and Networking by wuyunqing

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									Data Communication and Networking
Data Communication:
Today computer is available in many offices and homes and therefore there is a need to share data
and programs among various computers. Data and information from one computer system can be
transmitted to other systems across geographical areas. Thus data transmission is the movement of
information using some standard methods. These methods include electrical signals carried along a
conductor, opticalsignals along an optical fibers and electromagnetic areas.
Basic Elements of a Communication System
The following are the basic requirements for working of a communication system.
       1. The sender (source) who creates the message to be transmitted
       2. A medium that carries the message
       3. The receiver (sink) who receives the message.
       Data : A collection of facts in raw forms that become information after processing.
       Signals : Electric or electromagnetic encoding of data.
       Signaling : Propagation of signals across a communication medium.
       Transmission : Communication of data achieved by the processing of signals.
A Communication Model
The Model




                                   Standard Communication Model
The parts of this model are as follows:
    Sender: The sender is what or who is trying to send a message to the receiver.
    Encoder: In the general case, it is not possible to directly insert the message onto the
       communications medium. For instance, when you speak on the telephone, it is not possible
       to actually transmit sound (vibrations in matter) across the wire for any distance. In your
       phone is a microphone, which converts the sound into electrical impulses, which can be
       transmitted by wires. Those electrical impulses are then manipulated by the electronics in
       the phone so they match up with what the telephone system expects.
    Message: Since this is a communication engineer's model, the message is the actual
       encoded message that is transmitted by the medium.
    Medium: The medium is what the message is transmitted on. The phone system, Internet,
       and many other electronic systems use wires. Television and radio can use electromagnetic
       radiation. Even bongo drums can be used as a medium
    Decoder: The decoder takes the encoded message and converts it to a form the receiver
       understands, since for example a human user of the phone system does not understand
       electrical impulses directly.
    Receiver: The receiver is the target of the message.




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The four basic components, of this model are:




                                    Simplified Communication Model
The base unit of this model can be called a connection.
connection
        If there is an identifiable sender, receiver, and medium, they define a connection along
        which a message can flow. When the sender sends a message, the medium transmits it, and
        the receiver receive the message.
A connection is always unidirectional in this model. If communication flows in both directions,
that should be represented as two connections, one for each direction.
Data Transmission Modes:
There are three ways for transmitting data from one point to another:
1. Simplex : In simplex mode the communication can take place in one direction. The receiver
receives the signal from the transmitting device. In this mode the flow of information is Uni-
directional. Hence it is rarely used for data communication.
                            A                             B
                                 Simplex A to B only
2. Half-duplex : In half-duplex mode the communication channel is used in both directions, but
only in one direction at a time. Thus a half-duplex line can alternately send and receive data.
                            A                                  B
                                Half-Duplex A to B or B to A
3. Full-duplex : In full duplex the communication channel is used in both directions at the same
time. Use of full-duplex line improves the efficiency as the line turnaround time required in half-
duplex arrangement is eliminated. Example of this mode of transmission is the telephone line.
                        A                                B
                            Full-Duplex A to B and B to A
Communication Media
Following are the major communication devices which are frequently used :


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  1. Wire Pairs : Wire pairs are commonly used in local telephone communication and for short
  distance digital data communication. They are usually made up of copper and the pair of wires is
  twisted together. Data transmission speed is normally 9600 bits per second in a distance
  of 100 meter.


  2. Coaxial Cables : Coaxial cable is groups of specially wrapped and insulated wires that are able
  to transfer data at higher rate. They consist of a central copper wire surrounded by an insulation
  over which copper mesh is placed. They are used for long distance telephone lines and local
  area network for their noise immunity and faster data transfer.




  Coaxial Cable is a high quality, well insulated cable capable of transmitting data over short
  distances. It is most commonly used in LAN’s, found to be cheap and simple to connect.
  Coaxial cable is used as a transmission line for radio frequency signals, in applications such as
  connecting radio transmitters and receivers with their antennas, computer network (Internet)
  connections, and distributing cable television signals.

  3. Twisted pair
  Twisted pair cabling is a type of wiring in which two conductors
  (the forward and return conductors of a single circuit) are twisted
  together for the purposes of canceling out electromagnetic interference
  (EMI) from external sources; for instance, electromagnetic radiation
  from Unshielded Twisted Pair (UTP) cables, and crosstalk between
  neighboring pairs.

  4. UTP (Unshielded Twisted Pair) is a copper cable used in much of the telephone networks.
     Unless shielded it can be a security risk since it radiates to its surroundings! It is cheap and
     easy to install.


5. Microwave : Microwave system uses very high frequency radio signals to
transmit data through space. The transmitter and receiver of a microwave system
should be in line-of-sight because the radio signal cannot bend. With microwave
very long distance transmission is not possible. Microwave is similar to radio waves.
Due to the earths curvature and as microwaves travel in straight lines, microwaves
stations can not be 30 miles apart. This is one key reason why you may experience
no reception on your cell phones; you may be out of reach from a transmitter /receiver.

  6. Communication Satellite : The problem of line-sight and repeaters are
  overcome by using satellites which are the most widely used data
  transmission media in modern days. In satellite communication, microwave
  signal is transmitted from a transmitter on earth to the satellite at space.
  The satellite amplifies the weak signal and transmits it back to the receiver.
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7. Ethernet
Ethernet is a family of frame-based computer networking technologies for local area networks
(LANs). The name comes from the physical concept of the ether.
8. Ethernet hub
A network hub or repeater hub is a device for connecting multiple twisted pair or fiber optic
Ethernet devices together and thus making them act as a single network segment.

9. Gateway
           o   A gateway may contain devices such as protocol translators, impedance matching
               devices, rate converters, fault isolators, or signal translators as necessary to provide
               system interoperability. It also requires the establishment of mutually acceptable
               administrative procedures between both networks.
           o   A protocol translation/mapping gateway interconnects networks with different
               network protocol technologies by performing the required protocol conversions.

10. Modem:
A modem (modulator-demodulator) is a device that modulates an analog carrier signal to encode
digital information, and also demodulates such a carrier signal to decode the transmitted
information. The goal is to produce a signal that can be transmitted easily and decoded to
reproduce the original digital data. Modems can be used over any means of transmitting analog
signals, from driven diodes to radio.

Computer networking:
A computer network is any set of computers or devices connected to each other with the ability to
exchange data. A computer network is interconnection of various computer systems located at
different places. In computer network two or more computers are linked together with a medium
and data communication devices for the purpose of communication data and sharing resources.
The computer that provides resources to other computers on a network is known as server. In the
network the individual computers, which access shared network resources, are known as nodes.
There are three types of networks: 1. Internet. 2. Intranet. 3. Extranet.

Types of Networks
    1. Local-Area Networks (LANs)
LAN is a computer network that spans a relatively small area. Most LANs are confined to a single
building or group of buildings. LANs are capable of transmitting data at very fast rates, much
faster than data can be transmitted over a telephone line; but the distance are limited, and there is
also a limit on the number of computers that can be attached to a single LAN.
A local area network is a network that spans a relatively small space and provides services to a
small number of people. Local area network (LAN), which is usually a small network constrained
to a small geographic area. An example of a LAN would be a computer network within a building.
    • Limited geographical ares (1 to 10 km)
    • Owned and administered by the user group (Network administrator(s))
    • Less than 1000 users.
    • A wide choice of media and topologies are available.

   2. Wide area network (WAN)


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A WAN is a computer network that spans a relatively large geographical area. Typically, A WAN
consists of two or more local-area networks (LANs).Computers connected to a wide-area network
are often connected through public networks, such as the telephone system. They can also be
connected through leased lines or satellites.
A wide area network is a network where a wide variety of resources are deployed across a large
domestic area or internationally. An example of this is a multinational business that uses a WAN to
interconnect their offices in different countries. The largest and best example of a WAN is the
Internet, which is a network composed of many smaller networks. The Internet is considered the
largest network in the world.

    3. Metropolitan area network (MAN)
MAN integrates two or more LAN networks over a specific geographical area ( usually a city ) so
as to increase the network and the flow of communications. Metropolitan area network (MAN),
which is used for medium size area. examples for a city or a state.

   4. Wireless networks (WLAN, WWAN)
A wireless network is basically the same as a LAN or a WAN but there are no wires between hosts
and servers. The data is transferred over sets of radio transceivers. These types of networks are
beneficial when it is too costly or inconvenient to run the necessary cables.

Network topology
Network topology is the physical interconnections of the elements (links, nodes, etc.) of a
computer network. A local area network (LAN) is one example of a network that exhibits both a
physical topology and a logical topology.

Basic topology types
The study of network topology recognizes five basic topologies:
      Bus topology
      Star topology
      Ring topology
      Tree topology
      Mesh topology

   1. Bus network topology
       In local area networks where bus technology is used, each machine is connected to a single cable.
       Each computer or server is connected to the single bus cable through some kind of connector.




   2. Star network topology


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In local area networks where the star topology is used, each machine is connected to a central hub.
In contrast to the bus topology, the star topology allows each machine on the network to have a
point to point connection to the central hub.




   3. Ring network topology

       In local area networks where the ring topology is used, each computer is connected to the
       network in a closed loop or ring. Each machine or computer has a unique address that is used for
       identification purposes. The signal passes through each machine or computer connected to the
       ring in one direction.




    4. Mesh network topology
The value of fully meshed networks is proportional to the exponent of the number of subscribers,
assuming that communicating groups of any two endpoints, up to and including all the endpoints.




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    5. Tree network topology: Also known as a hierarchical network.
The type of network topology in which a central 'root' node (the top level of the hierarchy) is
connected to one or more other nodes that are one level lower in the hierarchy (i.e., the second
level) with a point-to-point link between each of the second level nodes and the top level central
'root' node, while each of the second level nodes that are connected to the top level central 'root'
node will also have one or more other nodes that are one level lower in the hierarchy (i.e., the third
level) connected to it, also with a point-to-point link, the top level central 'root' node being the only
node that has no other node above it in the hierarchy.




Internet:
The Internet is a global system of interconnected computer networks that use the standard Internet
Protocol Suite to serve billions of users worldwide. It is a network of networks that consists of
millions of private and public, academic, business, and government networks of local to global
scope that are linked by a broad array of electronic and optical networking technologies.
Today, the Internet is a public, cooperative, and self-sustaining facility accessible to hundreds of
millions of people worldwide. Physically, the Internet uses a portion of the total resources of the
currently existing public telecommunication networks. Technically, what distinguishes the
Internet is its use of a set of protocols called TCP/IP (for Transmission Control Protocol/Internet
Protocol). Two recent adaptations of Internet technology, the intranet and the extranet, also make
use of the TCP/IP protocol.


Advantages Of Internet
The Internet provides many facilities to the people. The main advantages of Internet are:-
 1. Sharing Information
You can share information with other people around the world. The scientist or researchers can
interact with each other to share knowledge and to get guidance etc. Sharing information through
Internet is very easy, cheap and fast method.
2. Collection of Information:
You can get latest news of the world on the Internet. Most of the newspapers of the world are also
available on the Internet. They have their websites from where you can get the latest news about
the events happening in the world. These websites are periodically updated or they are
immediately updated with latest news when any event happens around the world. The Internet is a

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virtual treasure trove of information. Any kind of information on any topic under the sun is
available on the Internet. The search engines like Google, yahoo is at your service on the Internet.
You can almost find any type of data on almost any kind of subject that you are looking for.
3. Services & Jobs:
You can search different types of jobs all over the world, Most of the organizations/departments
around the world, advertise their vacant vacancies on the Internet. The search engines are also used
to search the jobs on Internet. You can apply for the required job through Internet. Many services
are now provided on the internet such as online banking, job seeking, purchasing tickets for your
favorite movies, guidance services on array of topics engulfing the every aspect of life, and hotel
reservations.
4. Advertisement
Today, most of the commercial organizations advertise their product through Internet. It is very
cheap and efficient way for the advertising of products. The products can be presented with
attractive and beautiful way to the people around the world.
5. Communication
Now we can communicate in a fraction of second with a person who is sitting in the other part of
the world. Today for better communication, we can avail the facilities of e-mail; we can chat for
hours with our loved ones. There are plenty messenger services in offering. With help of such
services, it has become very easy to establish a kind of global friendship where you can share your
thoughts, can explore other cultures of different ethnicity. For this purpose, different services are
provided on the Internet such as;
     Chatting
     Video conferencing
     E-mail
     Internet telephony etc.

7. Entertainment
Internet also provides different type of entertainments to the people. You can play games with
other people in any part of the world. Similarly, you can see movies, listen music etc. You can also
make new friends on the Internet for enjoyment.
8. Online Education
Internet provides the facility to get online education. Many websites of different universities
provide lectures and tutorials on different subjects or topics. You can also download these lectures
or tutorials into your own computer. You can listen these lectures repeatedly and get a lot of
knowledge. It is very cheap and easy way to get education.
9. Online Results
Today, most of the universities and education boards provide results on the Internet. The students
can watch their results from any part of country or world.

10. Online Airlines and Railway Schedules
Many Airline companies and Pakistan Railway provide their schedules of flights and trains
respectively on the Internet.
11. Online Medical Advice



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Many websites are also available on the Internet to get information about different diseases. You
can consult a panel of online doctors to get advice about any medical problem. In addition, a lot of
material is also available on the Internet for research in medical field.

Disadvantages of Internet

1. Theft of Personal information
If you use the Internet, you may be facing grave danger as your personal information such as
name, address, credit card number etc. can be accessed by other culprits to make your problems
worse.

2. Spamming:
Spamming refers to sending unwanted e-mails in bulk, which provide no purpose and needlessly
obstruct the entire system. Such illegal activities can be very frustrating for you, and so instead of
just ignoring it, you should make an effort to try and stop these activities so that using the Internet
can become that much safer.
3. Virus threat
Virus is nothing but a program which disrupts the normal functioning of your computer systems.
Computers attached to internet are more prone to virus attacks and they can end up into crashing
your whole hard disk, causing you considerable headache.

4. Pornography:
This is perhaps the biggest threat related to your children’s healthy mental life. A very serious
issue concerning the Internet. There are thousands of pornographic sites on the Internet that can be
easily found and can be a detrimental factor to letting children use the Internet.

5. Viruses
Today, Internet is the most popular source of spreading viruses. Most of the viruses transfer from
one computer to another through e-mail or when information is downloaded on the Internet. These
viruses create different problems in your computer. For example, they can affect the performance
of your computer and damage valuable data and software stored in your computer.
6. Security Problems
The valuable websites can be damaged by hackers and your valuable data may be deleted.
Similarly, confidential data may be accessed by unauthorized persons.
7. Immorality
Some websites contains immoral materials in the form of text, pictures or movies etc. These
websites damage the character of new generation.
8. Accuracy of Information
A lot of information about a particular topic is stored on the websites. Some information may be
incorrect or not authentic. So, it becomes difficult to select the correct information. Sometimes you
may be confused.
9. Wastage of times
A lot of time is wasted to collect the information on the Internet. Some people waste a lot of time
in chatting or to play games. At home and offices, most of the people use Internet without any
positive purpose.
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10. English language problems
Most of the information on the Internet is available in English language. So, some people cannot
avail the facility of Internet.


Electronic Mail (E-mail):
Electronic mail, most commonly abbreviated email is a method of exchanging digital messages. E-
mail systems are based on a store-and-forward model in which e-mail computer server systems
accept, forward, deliver and store messages on behalf of users.
An electronic mail message consists of two components, the message header, and the message
body, which is the email's content. The message header contains control information, including,
minimally, an originator's email address and one or more recipient addresses. Usually additional
information is added, such as a subject header field.
E-mail has many advantages over both ordinary mail and the telephone.
For example:
    • A message can be sent anywhere in the world at the price of a local call, without having to
         leave your desk;
    • The same message can be sent simultaneously to a group of people;
    • The message will arrive in at most a few hours, and can be picked up the next time the
         recipient looks at their e-mail;
    • It is very easy to send a reply to an e-mail as soon as it is received, using a ‘Reply’ button;
    • Long files including video, sound and graphics can be sent automatically when the cheap rate
         starts after 6pm, (or especially between Midnight Friday and Midnight Sunday).
    • Graphics and text can be electronically transmitted and placed in a document by the recipient.

Advantages of Email
   1. Relatively low cost of fulfilment. The physical costs of email are substantially less than
      direct mail.
   2. Direct response medium encourages immediate action. Email marketing encourages
      clickthrough to a website where the offer can be redeemed immediately this increases the
      likelihood of an immediate, impulsive response.
   3. Faster campaign deployment. Lead times for producing creative and the whole campaign
      lifecycle tends to be shorter than traditional media.
   4. Ease of personalisation. It is easier and cheaper to personalise email than for physical
      media and also than for a website.
   5. Options for testing. It is relatively easy and cost effective to test different email creative
      and messaging.
   6. Integration. Through combining email marketing with other direct media which can be
      personalised such as direct mail, mobile messaging or web personalisation, campaign
      response can be increased as the message is reinforced by different media.
   7. Managing Email is Easy: You can manage all your correspondence on screen and so can
      your customers. Your proposal can be answered, revised, stored, and sent to others, all
      without reams of paper involved.
   8. Email is Fast: Mail is delivered instantly...from your office to anywhere in the world. No
      other method of delivery can provide this service. Timely buying and selling decisions can
      be made in a heartbeat.
   9. Email is Inexpensive: Compared to telephone calls, faxes, or over night courier service,
      Email is less expensive.
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   10. Email is an Internet marketing tool that is fast, easy to use, inexpensive and effective.
       Email levels the playing field between the big corporations and small businesses. No longer
       is it just the big boys who have the resources to access the big advertising houses. Anyone
       can get their word out there using Email as the method of delivering the message.
Disadvantages of Email Marketing
   1. Deliverability. Difficulty of getting messages delivered through different internet service
       providers (ISPs), corporate firewalls and webmail systems.
   2. Renderability. Difficulty of displaying the creative as intended within the in-box of
       different email reading systems.
   3. Email response decay. Email recipients are most responsive when they first subscribe to an
       email. It is difficult to keep them engaged.
   4. Communications preferences. Recipients will have different preferences for email offers,
       content and frequency which affect engagement and response. These have to be managed
       through communications preferences.
   5. Resource intensive. Although email offers great opportunities for targeting, personalisation
       and more frequent communications, additional people and technology resources are
       required to deliver these
   6. Email creates more work: In contrast to the popular notion, email actually creates more
       work. The easy of sending and receiving email has transformed businesses throughout the
       world and we know that the stress levels are increase, right.
   7. People expect immediate replies Most people know that emails are delivered
       instantaneously and hence expect replies immediately.
   8. Most email messages are not secure.

Chatting:

On the Internet, chatting is talking to other people who are using the Internet at the same time you
are. Usually, this "talking" is the exchange of typed-in messages requiring one site as the
repository for the messages (or "chat site") and a group of users who take part from anywhere on
the Internet. In some cases, a private chat can be arranged between two parties who meet initially
in a group chat. Chats can be ongoing or scheduled for a particular time and duration. Most chats
are focused on a particular topic of interest and some involve guest experts or famous people who
"talk" to anyone joining the chat.



Chat Rooms:

         - A chat room is a Web site, part of a Web site, or part of an online service such as
America Online, that provides a venue for communities of users with a common interest to
communicate in real time. Forums and discussion groups, in comparison, allow users to post
messages but don't have the capacity for interactive messaging.
Chat room users register for the chat room of their choice, choose a user name and password, and
log into a particular room Inside the chat room, generally there is a list of the people currently
online, who also are alerted that another person has entered the chat room. To chat, users type a
message into a text box. The message is almost immediately visible in the larger communal
message area and other users respond. Users can enter chat rooms and read messages without
sending any, a practice known as lurking.
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What is NetMeeting?
NetMeeting is a data conferencing application program that allows you to communicate and
collaborate with other people in real-time over the Internet. With NetMeeting you can share
applications, exchange information through a shared clipboard, transfer files, collaborate on a
shared whiteboard, and communicate with a text-based chat feature.
NetMeeting can be a valuable tool for distance learning or training purposes. A wealth of
information about using this valuable online conferencing tool is already available on the Internet.
The guide will serve as a basic tutorial and a focused gateway especially designed for instructors,
and students.
What Do I Need?
      A PC running a Windows variant, such as Windows 95, Windows 98, Windows NT 4.0,
       Windows 2000 or Windows XP. You should have Internet Explorer 4.0 or better installed
       as well. Note that Windows XP and 2000 come with Netmeeting already installed.
      The PC should a reasonably current machine, such as a Pentium II 233 MHZ or better. A
       slower machine may work, but audio and video performance will suffer. It should have a
       decent amount of Ram (64 MB or better). A sound card is not mandantory, but for audio
       conferencing, some sort of audio interface is necessary.
      A Microphone and Headphones
       If you want to participate in an audio conference, you need a microphone. You need not
       spend a lot of money. You can also opt for a headset that has the microphone built in; this
       is all a matter of preference.
      A Network connection
       While it is possible to use some functions in NetMeeting with a 56k modem, a faster
       network connection is preferable. A Cable Modem or DSL connection is perfectly adequate
       for any of the features in NetMeeting when at home.

Web design:
Web design is the skill of creating presentations of content that is delivered to an end-user through
the World Wide Web, by way of a Web browser or other Web-enabled software like Internet
television clients, microblogging clients and RSS readers.
The intent of web design is to create a web site—a collection of electronic files that reside on a
web server/servers and present content and interactive features/interfaces to the end user in form of
Web pages once requested.
Typically web pages are classified as static or dynamic:
      Static pages don’t change content and layout with every request unless a human (web
        master/programmer) manually updates the page. A simple HTML page is an example of
        static content.
      Dynamic pages adapt their content and/or appearance depending on end-user’s
        input/interaction or changes in the computing environment (user, time, database
        modifications, etc.) Content can be changed on the client side (end-user's computer) by
        using client-side scripting languages (JavaScript, JScript, Actionscript, etc.) to alter DOM
        elements (DHTML).
The process of designing web pages, web sites, web applications or multimedia for the Web may
utilize multiple disciplines, such as animation, authoring, communication design, corporate
identity, graphic design, human-computer interaction, information architecture, interaction design,
marketing, photography, search engine optimization and typography.
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        Markup languages (such as HTML, XHTML and XML)
        Style sheet languages (such as CSS and XSL)
        Client-side scripting (such as JavaScript)
        Server-side scripting (such as PHP and ASP)
        Database technologies (such as MySQL and PostgreSQL)
        Multimedia technologies (such as Flash and Silverlight)
Web pages and web sites can be static pages, or can be programmed to be dynamic pages that
automatically adapt content or visual appearance depending on a variety of factors, such as input
from the end-user, input from the Webmaster or changes in the computing environment (such as
the site's associated database having been modified).
With growing specialization within communication design and information technology fields,
there is a strong tendency to draw a clear line between web design specifically for web pages and
web development for the overall logistics of all web-based services.




                                Electronic Commerce:
        Electronic Commerce or e-commerce is the trade of products and services by means of the
Internet or other computer networks. E-commerce follows the same basic principles as traditional
commerce that is, buyers and sellers come together to swap commodities for money. Electronic
commerce can be between two businesses transmitting funds, goods, services and/or data or
between a business and a customer. Electronic commerce, consists of the buying and selling of
products or services over electronic systems such as the Internet and other computer networks.
Types of E-Commerce:
    1. Electronic Data Interchange (EDI):
EDI is the structured exchange of information between applications in different companies. It is
about the relationships among companies. In a world that's getting smaller and smaller, and where
even the smallest company can display its products before a worldwide audience, the
interdependence of companies grows constantly. EDI is the exchange of business data using an
understood data format. EDI involves data exchange among parties that know each other well and
make arrangements for one-to-one (or point-to-point) connection, usually dial-up.
    2. Internet commerce:
Broad term covering all commercial activity on the internet, including auctioning, placing orders,
making payments, transferring funds, and collaborating with trading partners.
E-commerce is also conducted through email, instant messaging and social networking sites such
as Facebook or Twitter. To avoid the perception of spam, The internet can be used for advertising
goods and services and transacting one-off deals. Internet commerce has application for both
business to business and business to customer transactions.
    3. Electronic Market :
The principal function of an electronic market is to facilitate the search for the required product or
service. Electronic market helps in building customer relationships and easier to own and operate
more than one business or entity Online. Airline Booking System is an example of an electronic
market.

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Advantages Of E-Business Applications:
     Being able to conduct business 24 x 7 x 365 . E-commerce systems can operate all day
      every day. Your physical storefront does not need to be open in order for customers and
      suppliers to be doing business with you electronically. Customers can easily select products
      from different providers without moving around physically.
     Access the global marketplace . The Internet spans the world, and it is possible to do
      business with any business or person who is connected to the Internet. This global
      opportunity is assisted by the fact that, unlike traditional communications methods, users
      are not charged according to the distance over which they are communicating. The Internet
      allows you to reach people around the world, offering your products to a global customer
      base.
     Speed. Electronic communications allow messages to traverse the world almost
      instantaneously. There is no need to wait weeks for a catalogue to arrive by post: that
      communications delay is not a part of the Internet / e-commerce world.
     Opportunity to reduce costs. The Internet makes it very easy to 'shop around' for products
      and services that may be cheaper or more effective than we might otherwise settle for.
      Electronic commerce gives the customers the opportunity to look for cheaper and quality
      products. Besides these, people also come across reviews posted by other customers, about
      the products purchased from a particular e-commerce site, which can help make purchasing
      decisions.
     Stepping beyond borders to a global view. Using aspects of e-commerce technology can
      mean your business can source and use products and services provided by other businesses
      in other countries. It enables a business concern or individual to reach the global market. It
      caters to the demands of both the national and the international market.
     Increases Profitability:
      Electronic commerce reduces the burden of infrastructure to conduct businesses and
      thereby raises the amount of funds available for profitable investment. For business
      concerns, e-commerce significantly cuts down the cost associated with marketing,
      customer care, processing, information storage and inventory management.
     Catalog flexibility and Online fast updating
      Direct "link" capabilities to content information and visual displays already existing on
      other client web site. You can update your E-Catalog anytime, whether it's adding new
      products, or adjusting prices, without the expense and time of a traditional print catalog.
      Extensive search capabilities by item, corporate name, division name, location,
      manufacturer, partner, price or any other specified need.
    Shrinks the Competition Gap
     Reduced marketing/advertising expenses, compete on equal footing with much bigger
     companies; easily compete on quality, price, and availability.
    Lower Cost of Doing Business
     Reduce inventory, employees, purchasing costs, order processing costs associated with
     faxing, phone calls, and data entry, and even eliminate physical stores. Reduce transaction
     costs. Reduce unnecessary phone calls and mailings.
    Eliminate Middlemen & Frees Your Staff
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       Sell directly to your customers hence reduces customer service and sales support.
    More Efficient Business Relationships
     Better way to deal with dealers and suppliers. Gives customers control of sales process.
     Builds loyalty. .

Disadvantages of Electronic Commerce

    Time for delivery of physical products . It is possible to visit a local music store and walk
     out with a compact disc, or a bookstore and leave with a book. E-commerce is often used
     to buy goods that are not available locally from businesses all over the world, meaning that
     physical goods need to be delivered, which takes time and costs money.
      Physical product, supplier & delivery uncertainty . When you walk out of a shop with
       an item, it's yours. You have it; you know what it is, where it is and how it looks. The time
       period required for delivering physical products can also be quite significant in case of e-
       commerce. Secondly, because supplying businesses can be conducted across the world, it
       can be uncertain whether or not they are legitimate businesses and are not just going to take
       your money. It's pretty hard to knock on their door to complain or seek legal recourse!
       Thirdly, even if the item is sent, it is easy to start wondering whether or not it will ever
       arrive.
      Perishable goods . Forget about ordering a single gelato ice cream from a shop in Rome!
       Though specialised or refrigerated transport can be used, goods bought and sold via the
       Internet tend to be durable and non-perishable. Durable goods can be traded from almost
       anyone to almost anyone else, sparking competition for lower prices. In some cases this
       leads to disintermediation in which intermediary people and businesses are bypassed by
       consumers and by other businesses that are seeking to purchase more directly from
       manufacturers.
      Limited and selected sensory information. The Internet is an effective conduit for visual
       and auditory information: seeing pictures, hearing sounds and reading text. However it
       does not allow full scope for our senses: we can see pictures of the flowers, but not smell
       their fragrance; we can see pictures of a hammer, but not feel its weight or balance. If we
       were looking at buying a car on the Internet, we would see the pictures the seller had
       chosen for us to see but not the things we might look for if we were able to see it in person.
       And, taking into account our other senses, we can't test the car to hear the sound of the
       engine as it changes gears or sense the smell and feel of the leather seats.
      Returning goods. Returning goods online can be an area of difficulty. The uncertainties
       surrounding the initial payment and delivery of goods can be exacerbated in this process.
       Will the goods get back to their source? Who pays for the return postage? Will the refund
       be paid? Will I be left with nothing? How long will it take? Contrast this with the offline
       experience of returning goods to a shop. A lot of phone calls and e-mails may be required
       till you get your desired products. However, returning the product and getting a refund can
       be even more troublesome and time consuming than purchasing, in case if you are not
       satisfied with a particular product.
      Privacy, security, payment, identity, contract. Many issues arise - privacy of
       information, security of that information and payment details, whether or not payment


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      details (eg credit card details) will be misused, identity theft, contract, and, whether we
      have one or not, what laws and legal jurisdiction apply.
     Size and number of transactions. E-commerce is most often conducted using credit card
      facilities for payments, and as a result very small and very large transactions tend not to be
      conducted online. The size of transactions is also impacted by the economics of
      transporting physical goods. For example, any benefits of buying a box of pens online from
      a US-based business tend to be added to delivery cost for reaching India. The delivery costs
      also mean that buying individual items is significantly more expensive than buying all of
      the goods from one overseas business because the goods can be packaged and shipped
      together.
     Restricted to limited people: One important disadvantage of e-commerce is that the
      Internet has still not touched the lives of a great number of people, either due to the lack of
      knowledge or trust. A large number of people do not use the Internet for any kind of
      financial transaction.
     Other Disadvantages: Any one, good or bad, can easily start a business. And there are
      many bad sites which eat up customers’ money. Mechanical failures can cause
      unpredictable effects on the total processes. As there is minimum chance of direct customer
      to company interactions, customer loyalty is always on a check. There are many hackers
      who look for opportunities, and thus an ecommerce site, service, payment gateways, all are
      always prone to attack.

There are mainly six types of e-commerce models:
  1. Business to Consumer (B2C) - As the name suggests, it is the model involving businesses
     and consumers. This is the most common e-commerce segment. In this model, online
     businesses sell to individual consumers.
     The basic concept behind this type is that the online retailers and marketers can sell their
     products to the online consumer by using crystal clear data which is made available via
     various online marketing tools.
     E.g. An online pharmacy giving free medical consultation and selling medicines to patients.
     With B2C E-Commerce, the retailers is often selling to unknown, un-trusted strangers.
     Therefore extra effort must be made to capture customer and payment information.
     However, B2C almost always involves a customer typing information into an order screen,
     there is no need to link together two complex accounting systems
     As nearly all online stores will require the same functions: catalogues, order baskets,
     payment processing, content management and member management, it makes sense for
     those components to be created once and shared by all stores. Anyone who wants to sell
     products and services over the internet, or who wants customers to be able to research their
     purchases on the internet, should consider an online store.
  2. Business to Business (B2B) - It is the largest form of e-commerce involving business of
     trillions of dollars. In this form, the buyers and sellers are both business entities and do not
     involve an individual consumer. It is like the manufacturer supplying goods to the retailer
     or wholesaler. E.g. Dell sells computers and other related accessories online but it is does
     not manufacture all those products. So, in order to sell those products, it first purchases
     them from different businesses i.e. the manufacturers of those products. B2B involves
     widening the circle of suppliers (for safety and competition), and of centralizing control
     (for records and discounts). B2B ecommerce is an important part of any online business by
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     guaranteeing of quality and delivery of goods, reporting: approval of sale, invoicing,
     delivery, payment and safeguarding against fraud.
  3. Consumer to Consumer (C2C) - It facilitates the online transaction of goods or services
     between two people. E-Commerce has also emerged that allows unknown, un-trusted
     parties to sell goods and services to one-another. An excellent example of this is found at
     Ebay, where consumers sell their goods and services to other consumers. Firstly, Ebay
     allows all sellers and buyers to rate one another. The purchasers may see that a particular
     seller has sold to more than 2,000 customers - all of whom rate the seller as excellent. This
     type of information is helpful. Another technology that has emerged to support C2C
     activities is that of the payment intermediary. Pay Pal is a good example of this. Instead of
     purchasing items directly from an unknown, un-trusted seller, the buyer can instead send
     the money to Pay Pal. From there, Pay Pal notifies the seller that they will hold the money
     for them until the goods have been shipped and accepted by the buyer. Other examples of
     Consumer-to-Consumer applications are service and employment websites such as
     Monster.com, Seek.com.au and CareerOne.com.au. These websites provide a valuable
     service to consumers looking for jobs. Employers can advertise on these websites and
     potential employees can contact their organization for an interview.
  4. Peer to Peer (P2P) - Though it is an e-commerce model but it is more than that. It is a
     technology in itself which helps people to directly share computer files and computer
     resources without having to go through a central web server. To use this, both sides need to
     install the required software so that they can communicate on the common platform..
  5. m-Commerce - It refers to the use of mobile devices for conducting the transactions. The
     mobile device holders can contact each other and can conduct the business. Even the web
     design and development companies optimize the websites to be viewed correctly on mobile
     devices.
  6. B2E (Business to Employee) E-Commerce generally refers to the requisitioning of
     supplies by employees for use in their jobs, but this really has grown to encompass much
     more. For example, B2E makes it very easy for an employee to requisition a new toner
     cartridge and printer paper - the order is entirely electronic, and supervisors are asked to
     approved the requisition in the event that the total order exceeds preset limits for that
     particular employee.

Benefits Of Ecommerce
  1. Cheaper than Print Advertising: Many traditional businesses are used to more
     traditional marketing campaigns such as print and yellow pages advertising. Print
     advertising can get expensive as there may be a need to update regularly, which requires
     new work to be planned and generated. It is much quicker and most cost effective to update
     and maintain eCommerce marketing campaigns, specially as technology continues to
     improve.

  2. Interactive Ads or Marketing Campaigns: Using advertising that engages potential
     customers is key in todays fast paced, little time customer shopping space. One benefit to
     eCommerce marketing is the merchants ability to develop and improve a number of
     interactive advertising or marketing campaigns designed to reach out and engage shoppers.
     Videos, flash, presentations, graphics, moving animations. They can be used as interactive
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   devices to help entice shoppers to drop in and shop around for the product or services
   offered. Interactive ads and applications on the web are predicted to reach new heights as
   technology improves.

3. Builds Lasting Customer Relationships: The relationships you form with shoppers and
   existing customers can very well determine the overall success of any business, Online or
   off, however eBusiness has a lot more tools in building long standing customer
   relationships than traditional business do. Online eCommerce marketing and conducting
   business Online can have a direct influence on how customers view the overall brand or
   product.

4. Gather Feedback from Customers: Having a website that displays and offer products for
   sale is a great way to attract customers, make money and grow a business. eCommerce
   marketing initiatives aren’t always about a promotion or selling a product, some are meant
   to gather information or feedback from customers about how the business can improve.
   Conduction business Online and offering polls, questionaries and feedback forms is a great
   way to get direct input from existing customers and even shoppers who haven’t yet
   purchased.

5. Conduct Cheap Market Research: Trying to conduct market research for a brick and
   mortar store can be difficult and may take much time to plan and execute. With the
   availability of data on the Web and through the use of new technologies offered on the
   Web, eCommerce merchants are able to conduct market or product research quickly,
   efficiently and without hassle.

6. Lower Startup Cost Increase Efficiency and Profitability: Many a times it is much
   cheaper and takes less startup capital to open up an eCommerce business compared to a
   retail store location or chain. Online business does not require as many of the ingredients
   needed in business as a traditional business does. There’s typically no permits, fewer
   licenses, no lease to pay on, smaller utility bill, less or no employees to hire. Obviously, if
   it take less of the bottom line to get things up and running it will take less in return to
   generate a profit off of the eCommerce marketing.

7. Global Market Reach: The World Wide Web spans across and reaches exactly that, the
   world. With the reach and technology offered through eCommerce, merchants have the
   ability to target customers anywhere in the world, even smaller sections or local region.




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