A deep introduction to Internet and internet services. This ppt contains all the minor and major information about Internet from basic internet, www, concepts

1. Unit-1
Introduction to Internet
Definitions:-
 The Internet is a global System of interconnected computer networks. A
computer that connects to the Internet can access information from a vast.
 A large Global Network Comprised of thousands of smaller networks.
 A computer network consisting of worldwide network of computer
networks that use the TCP/IP network protocol to facilitate data
transmission.
The Internet sometimes called simply “the NET” is a world wide 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. It was
conceived by the Advanced Research Project Agency (ARPA) of the US.
government in 1969 and was first known as the “APPANET”.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.
Technically, what distinguishes the Internet is its use of a set of protocols called
TCP/IP (for Transmission Control Protocol/Internet Protocol).
For many Internet Users, Electronic Mail (e-mail) has practically replaced the
Postal Service for short written transactions. Electronic Mail is the most widely
used application on the Internet. You can also carry online “conversations” with
other computer users, using the Internet Relay Chat (IRC).
The most widely used part of the Internet is the World Wide Web (often
abbreviated “www” or called “the web”) .Its outstanding feature is hypertext, a
method of instant cross-referencing.

2. Internet Services
There are several types of services providedby the Internet.
1. E-mail
ElectronicMail isa methodof sendingamessage froma userat a computerto a recipienton
anothercomputer.
An e-mail messageconsistsof aheaderand the body of the message The firstpart,the header,
containsthe informationaboutwhere the messagehastobe sent,and the path thathas
followedtoreachitsdestination, aswell asotherinformationlikedate,returnpath,etc.The
bodyis the actual message thatis beingsent.
An e-mail addresshasthe form user@subdomain.subdomain.domain,e.g. rahul@imsc.res.in
2. FTP (File TransferProtocol)
FTP isan acronym forFile Transfer Protocol. As the name suggests, FTP is used to transfer files
between computers on a network, such as the Internet. FTP (File Transfer Protocol) is the
generictermfora groupof computerprogramsaimedatfacilitating the transfer of files or data
from one computer to another. This facility is a method of gaining limited access to another
machine in the Internet, and obtaining files from it.
How does it work?
FTP usesthe so-calledclient/servermodel.Onone side,there isthe customer - you- and on the
otherside there isa server,onwhichfilesare stored.
If one wishestostore orretrieve filesto/fromaserver,simplystartyourFTPprogram, and
specifythe hostname of the server,andausername andpassword.Once youhave loggedon
successfully,youwillbe able tobrowse throughthe filesanddirectoriesonthe remote server,
and uploadanddownloadfiles.
3. Telnet: logging in to Remote Network Computers
Telnet is the Internet facility that allows you to execute commands on a remote host
(another computer, most likely one to which you do not have physical access) as if you
were logged in locally. You need to know the name of the machine to which you want to
connect, and to have a valid user name in it. The commands for telnet are:
a. telnet hostname: it will open a connection to the host you name. For example,
"telnet math.sunysb.edu" will connect you to the machine named math.sunysb.edu
b. telnet "address": it opens a connection to the host at "address".

3. 4. GOPHER
Gopheris a menu-basedfacilitythatprovidesinformationaboutthe Internet.Althoughitwas
verypopulara fewyearsago,its usage has decreasedalotafterthe introductionof WWW. The
gophersystemissimilartothe Web.inthat you use a clienttoconnectto serversall overthe
world,one at a time.The informationispresentedasaseriesof simple menus.Eachgopher
serverhasa mainmenuan a seriesof sub-menus.Touse a gopher,all youneedtodo isselect
the menuitemyouwant,and yourclient will fetchitforyou.
5. Usenetand Mailinglist
If you wantto receive periodicallyinformationaboutcertaintopics,there are twothingsyoucan
do.The firstpossibilityistoreadthe newsgroupsof the Internet.Thisisamechanismto
broadcast news,calledarticles,fromyourlocal hostto the world.The newsserversare not
commonin India;unfortunately,toreadnewsyoumayneedtosetup a serverinyour local
host,and that takesquite alot of memory(youwill have toreserve abouthalf aGigabyte forit).
If you do nothave full Internetconnectivity,youcansubscribe toa mailinglist.Whatyouhave
to do isto sendyourname tosome server,andeverydayyou will receive e-mail containing
newsconcerningthe topicyouhave subscribedto.There are newsgroupsandmailinglistabout
anythingyoucan imagine,fromcomputerstoresearch,sports,politics,etc
6. WWW
The official description describes the World-Wide Web as a "wide-area *hypermedia*
information retrieval initiative aiming to give universal access to a large universe of
documents". The operation of the Web relies on hypertext as its means of interacting with
users. Hypertext is basically the same as regular text - it can be stored, read, searched, or
edited - with an important exception: hypertext contains connections within the text to
other documents.
For example, by clicking here you can get to the next document, while clicking in this
place will take you back to the Internet page.
.

4. What is the World Wide Web?
Definitions’:-
 Computernetworkconsistingof acollectionof internetsitesthatoffertextandgraphicsand
soundand animationresourcesthroughthe hypertext.
 The World Wide Web(commonlyabbreviatedas"the Web") isasystemof interlinkedhypertext
documentsaccessedviathe Internet.
 Collectively,all of the webpagesonthe Internetwhichhyperlinktoeachotherand to other
kindsof documentsandmedia;Internetresourcesthatare retrievedbyHypertextTransfer
Protocol (HTTP)
 The Web wasinventedin1991 by TimBerners-Lee,whileconsultingatCERN (European
OrganizationforNuclearResearch) inSwitzerland.
 The Web isa distributed information system.
 The Web contains multimedia.
 Informationinthe Webisconnectedby hyperlinks.
 The World Wide Web("WWW"orsimplythe "Web") isaglobal information mediumwhich
userscan read andwrite via computers connectedtothe Internet.
 The World Wide Web(knownas"WWW', "Web"or "W3") isthe universe of network-accessible
information,the embodiment of humanknowledge
Working of Internet
How does the Internet work?
Because the Internet is a global network of computers each computer connected to
the Internet must have a unique address. Internet addresses are in the form
nnn.nnn.nnn.nnn where nnn must be a number from 0 - 255. This address is
known as an IP address. (IP stands for Internet Protocol).
The picture belowillustrates two computers connected to the Internet; your computer with IP
address1.2.3.4 and anothercomputerwithIPaddress5.6.7.8. The Internetisrepresented as an
abstract object in-between

5. If you connect to the Internet through an Internet Service Provider (ISP), you are
usually assigned a temporary IP address for the duration of your dial-in session. If
you connect to the Internet from a local area network (LAN) your computer might
have a permanent IP address or it might obtain a temporary one from a DHCP
(Dynamic Host Configuration Protocol) server. In any case, if you are connected to
the Internet, your computer has a unique IP address.
Protocol Stacks and Packets
So your computer is connected to the Internet and has a unique address. How does
it 'talk' to other computers connected to the Internet? An example should serve
here: Let's say your IP address is 1.2.3.4 and you want to send a message to the
computer 5.6.7.8. The message you want to send is "Hello computer 5.6.7.8!".
Obviously, the message must be transmitted over whatever kind of wire connects
your computer to the Internet. Let's say you've dialed into your ISP from home and
the message must be transmitted over the phone line. Therefore the message must
be translated from alphabetic text into electronic signals, transmitted over the
Internet, then translated back into alphabetic text. How is this accomplished?
Through the use of a protocol stack. Every computer needs one to communicate on
the Internet and it is usually built into the computer's operating system (i.e.
Windows, Unix, etc.). The protocol stack used on the Internet is referred to as the
TCP/IP protocol stack because of the two major communication protocols used. The
TCP/IP stack looks like this:
Protocol Layer Comments
Application Protocols Layer
Protocols specific to applications such as WWW, e-mail, FTP,
etc.
Transmission Control
Protocol Layer
TCP directs packets to a specific application on a computer
using a port number.
Internet Protocol Layer
IP directs packets to a specific computer using an IP
address.
Hardware Layer
Converts binary packet data to network signals and back.
(E.g. ethernet network card, modem for phone lines, etc.)
If we were to follow the path that the message "Hello computer 5.6.7.8!" took from
our computer to the computer with IP address 5.6.7.8, it would happen something
like this:

6. 1. The message would start at the top of the protocol stack on your computer and work
it's way downward.
2. If the message to be sent is long, each stack layer that the message passes through
may break the message up into smaller chunks of data. This is because data sent
over the Internet (and most computer networks) are sent in manageable chunks. On
the Internet, these chunks of data are known as packets.
3. The packets would go through the Application Layer and continue to the TCP layer.
Each packet is assigned a port number. Ports will be explained later, but suffice to
say that many programs may be using the TCP/IP stack and sending messages. We
need to know which program on the destination computer needs to receive the
message because it will be listening on a specific port.
4. After going through the TCP layer, the packets proceed to the IP layer. This is where
each packet receives it's destination address, 5.6.7.8.
5. Now that our message packets have a port number and an IP address, they are
ready to be sent over the Internet. The hardware layer takes care of turning our
packets containing the alphabetic text of our message into electronic signals and
transmitting them over the phone line.
6. On the other end of the phone line your ISP has a direct connection to the Internet.
The ISPs router examines the destination address in each packet and determines
where to send it. Often, the packet's next stop is another router. More on routers
and Internet infrastructure later.
7. Eventually, the packets reach computer 5.6.7.8. Here, the packets start at the
bottom of the destination computer's TCP/IP stack and work upwards.
8. As the packets go upwards through the stack, all routing data that the sending
computer's stack added (such as IP address and port number) is stripped from the
packets.
9. When the data reaches the top of the stack, the packets have been re-assembled
into their original form, "Hello computer 5.6.7.8!"
Networking Infrastructure:-
So now you know how packets travel from one computer to another over the Internet.

7. Internet Connection concepts
The connectiontypesinthissectioninclude:
 Dial-upConnections
 ADSL Connections
 Cable Connections
ADSL and cable are typesof broadbandconnection,the term"broadband"onlyreferstothe
performance of aninternetconnection,nottoanyparticulartype of connection.
Dial-upconnections
Dial-upconnectionsare one type of internetconnectionavailable fromISPs, theyare the slowestand
(usually) the mostinexpensive.
A dial-upconnectionallowsyoutoconnectto the internetviaa local serverusingastandard 56k
modem.YourPC literallydials(hence the name) aphone number(providedbyyourISP) andconnectsto
the serverand therefore the internet.
Once connectedyoucan utilise all aspectsof the internet,the drawbackwithadial-upconnectionisthe
speed.A standard56k modemcan theoretically transfer56 Kilobitsof data a second,thismeansthat
youcan (againtheoretically) transferupto7 Kilobytesa second(althoughtogeta full 7kis near
impossible due tothe compressionoverhead).
Whenyouconsiderthat the average webpage includingitsimagesisaround50 Kilobytes,thismeansit
wouldtake around7 secondsforthe webpage to completelyloadinyourbrowser.
Dial-upconnectionPros
Dial-upconnectionscanbe veryeconomicandare widelyavailable,the cost perminute iscomparable
to that of a local phone call,orpricedas a monthlyplanwhichwillincludeacertainamountof time.As
these connectionsuse astandardmodemthe hardware costsare minimal,mostmodernlaptopshave a
built-in56Kmodem.
Dial-upconnectionCons
Dial-upconnectionsare veryslowcomparedtootherconnectiontypes.Whenconnectedtothe internet
the same phone line cannotbe usedforphone calls,soif anyone phonesyouwhenyouare connected
theywill getthe busysignal.
Dial-upconnectionstransferdataoveran analogue line sobeforethe dataissentit has tobe converted
fromdigital toanalogue,likewise whendataisreceivedithasto be convertedfromanalogue todigital

8. (thisiswhatthe modemdoes),thisaddsaperformance overheadwhichaffectsthe speedof the
connection.
ADSL connections
ADSL (AsymmetricDigital SubscribersLine) connectionsare becomingmore andmore widelyavailable
and can provide anexcellentinternetconnection.
The connectionsworkbysplittingyourphone line intotwoseparatechannels,one fordata(internet)
and one forvoice (phone calls),whichmeansyoucantalkonthe phone andbe connectedtothe
internetatthe same time.
You will oftensee ADSLconnectionservicesadvertisedashavingdifferentspeedspecifications,below
are some commonconfigurations:
 256Kbps/128Kbps
 512Kbps/128Kbps
 1Mbps/256Kbps
 2Mbps/512Kbps
 8Mbps/1024Kbps
Notice there are twovaluestoeach configuration,the firstfigure statesthe downloadspeedandthe
secondfigure isthe maximumuploadspeed.
ADSL connectionPros
Apart fromthe obviousspeedadvantagesthatADSLconnectionsoffer,ADSLtechnologyeliminatesthe
needfora secondphone line byallowingvoice anddatatransferat the same time (youcan use the
phone as normal while connectedtothe internet).
Because ADSLtransfersdata digitallyiteliminatesthe usual performanceoverheadassociatedwith
standarddial-upconnections,inotherwordsADSLdoesn'tneedtoconvertthe data fromdigital to
analogue andback again.
ADSL connectionCons
ADSL connectionsare notavailable toeveryone,youshouldalwaysensure thatyouhave ADSLcoverage
inyour area (anISP will checkforyou).The hardware costscan be quite significantasyouwill needa
special ADSLmodemandADSL filterstouse the service.MostISPsallow youtohire these itemswhich
can reduce the initial cost.
Cable connections
Cable connectionsare consideredone of the besttypesof internetconnectionavailable tothe home
user, theyofferveryfastandreliable connectionswithafixedmonthlyfee.
Cable companiesusuallyofferdifferentpackagestosuitdifferentinternetsubscribers,yourchoice of
package,as withall internetconnections,will dependonhow youintendtouse the internet.

9. The differentpackageswill offerdifferentspeedspecificationsandbandwidthlimits.
Because a cable connectionusesatotallyseparate mediumtotransferdatait doesn'taffectyourability
to make/receive phonecalls.
Cable connectionPros
Speedisa majorreasonfor havinga cable connection,withveryhighspeedpackagesavailableitisan
excellentchoice forthose whodon'tlike towaitaroundtappingtheirfingerswhendownloadingbigfiles
such as musicor large attachments.
Like ADSL connections,cable connectionstransferdatadigitally,eliminatinganydigital/analogue
conversionoverhead.
Cable connectionsare Alwayson,eliminatinglongwaitstomake a connection.
Cable connectionCons
Cable connectionsare notavailable ineveryarea,youwill needtocontactthe cable companyof your
choice to ensure thatyouhave coverage.
ISDN:-
ISDN (IntegratedServicesDigital Network):ISDN isaslightlyoldertechnologythatalsoprovidesahigh-
speedconnection.ISDN offersconnectionsoverordinarytelephone wire,facilitatingbothvoice and
data transmissionsoyoucan maintainyourconnectiontothe Internetwhile placingtelephone calls.
ISDN can be usedforindividualswhoneedtoconnectone computertoone line,orcan be usedto
connectmultiple computersinabuildingtothe Internet.
Wi-Fi:-
Wireless:isahigh-speedtechnologythattransmitsdataoverradiowaves.Wirelesstransmissioncanbe
usedto provide connectivityfromanISPtoan entire building,however,service willbe dependenton
the existence of aclearline of sightbetweenthe ISPandthe building.Withinabuilding,awirelesslocal
area network(LAN) canconnectmultiple computerstoeachotherandto the Internet.Wirelessisa
technologythatiscontinuallydeveloping.

10. Introduction to Intranet
Definition:-
Intranet is the generictermfora collectionof private computernetworkswithinanorganization.An
intranetusesnetworktechnologiesasatool to facilitate communicationbetweenpeopleorworkgroups
to improve the datasharingcapabilityandoverall knowledge base of anorganization'semployees.
An intranetisaninternal,securedbusinessenvironment,whichuses HTML andTCP/IPprotocolslike the
Internet,butoperateson a LAN (local areanetwork).
The Internethadmade the sharingof data and otherinformationbetweenbusinesses,the customers
and partnersextremelyeasy,evenif the usersare locatedacrossgreatdistances.Likewise,the
navigationof the WorldWide Webhas beenreadilystreamlinedinsucha waythat informationcanbe
retrievedquickly,andrequireslittle installedsoftware beyondaWebbrowser.However,the downside
of the Internetisthatthisinformationisalsoavailable insucha waythat itcan be foundandaccessed
by otherusers,aswell.
Benefitsofan Intranet
The main goal of an Intranet is to allow a company to share information among employees or
partners, but it can also limit access to the outside world. Sometimes access to the Web is
restricted so that workers don't spend a time surfing Web sites that have no relation to their
work. For a small business, there are many benefits of an Intranet:
 Greateraccess for all employees,especiallyforasmall ormedium-sizedbusinessthatmustrely
on the quicksharingof informationbetweenmultipleofficesorlocations.Thisprovides faster
and easieraccesstomore accurate company information.
 Ease of use for employees,because existingWebbrowserscanbe usedto navigate the Intranet.
Thisreducesthe needtoinstall specializedprogramsinmanycases,andfurtherrequireslittle
additional trainingof applications.
 Ease of shareddata, reducingthe needforprintoutsorotherhardcopies.
 Protectionof sensitive material,asuserslogintoa closednetworkanddatadoesnot have to be
sentout to usersindifferentofficesorthose workingremotely.Insteadthe dataisaccessby the
individual,thuslimitingthe chancesthata personoutside the companymightaccessit.
 Updatedinformationcanbe available toall usersatthe same time.

11. Configuring Internet Connection
How to use InternetConnectionSharing
To use InternetConnectionSharingtoshare yourInternetconnection,the hostcomputermusthave
one networkadapterthatis configuredtoconnecttothe internal network,andone networkadapteror
modemthatis configured toconnecttothe Internet.
On the host computer
On the hostcomputer,followthese stepstoshare the Internetconnection:
1. Log on to the host computerasAdministratororas Owner.
2. ClickStart, and thenclick Control Panel.
3. ClickNetworkand InternetConnections.
4. ClickNetworkConnections.
5. Right-clickthe connectionthatyouuse toconnectto the Internet.Forexample,if you
connectto the Internetbyusinga modem, right-clickthe connectionthatyouwantunder
Dial-up.
6. ClickProperties.
7. Clickthe Advanced tab.
8. Under InternetConnectionSharing,selectthe Allowothernetwork users to connect
through this computer'sInternetconnection checkbox.
9. If you are sharinga dial-upInternetconnection,selectthe Establisha dial-upconnection
whenevera computer on my network attempts to access the Internet checkbox if you
wantto permityourcomputerto automaticallyconnecttothe Internet.
10. ClickOK. You receive the followingmessage:
WhenInternetConnectionSharingisenabled,yourLAN adapterwill be settouse IP
address192.168.0.1. Your computermay lose connectivitywithothercomputerson
your network.If these othercomputershave staticIPaddresses,itisa goodideato setthem
to obtaintheirIPaddressesautomatically.Are you sure youwanttoenable Internet
ConnectionSharing?
11. ClickYes.
The connectiontothe Internetissharedtoothercomputersonthe local areanetwork(LAN).The
networkadapterthatis connectedtothe LAN is configured with a static IP address of 192.168.0.1 and a
subnet mask of 255.255.255.0

12. Connecting LAN to Internet
To configure the clientcomputertouse the sharedInternetconnection,followthese steps:
1. ClickStart, and thenclick Control Panel.
2. ClickNetworkand InternetConnections.
3. ClickInternetOptions.
4. In the InternetProperties dialogbox,clickthe Connectionstab.
5. Clickthe Setupbutton.
The NewConnectionWizardstarts.
6. On the Welcome tothe NewConnectionWizard page,click Next.
7. ClickConnectto the Internet,and thenclick Next.
8. ClickSetup my connectionmanually,and thenclick Next.
9. ClickConnectusing a broadband connectionthat is always on, and thenclick Next.
10. On the Completingthe NewConnectionWizard page,click Finish.
11. QuitControl Panel.
Whenyounow start MicrosoftInternetExplorer,the clientcomputerwill trytoconnectto the Internet
by usingthe hostcomputer'ssharedInternetconnection.
What Is DNS?
Domain Name System (DNS) is one of the industry-standard suite of protocols that comprise TCP/IP.
MicrosoftWindowsServer2003. DNSis implemented using two software components: the DNS server
and the DNS client (or resolver). Both components are run as background service applications.
Network resources are identified by numeric IP addresses, but these IP addresses are difficult for
networkusers to remember. The DNS database contains records that map user-friendly alphanumeric
namesfornetworkresourcestothe IP addressusedbythose resourcesfor communication. In this way,
DNS acts as a mnemonic device, making network resources easier to remember for network users.
The Windows Server 2003 DNS Server and Client services use the DNS protocol that is included in the
TCP/IP protocol suite. DNS is part of the application layer of the TCP/IP reference model.

13. Single User:-
Definition:single usermode:asystemmode createdforadministrative andmaintenance activities
demandcomplete control of the system.Whenthe systemisinthisstate whoeverisloggedinbecomes
root. Thisishowever,aminimal systemstartupstate
An importantrunlevel is singleusermode(runlevel 1),inwhichonlythe systemadministratorisusing
the machine andas fewsystemservices,includinglogins,aspossible are running.Single usermode is
necessaryfora fewadministrative tasks
Single usermode isa mode inwhicha multiusercomputeroperatingsystem bootsintoasingle super
user.It ismainlyusedformaintenance of multi-userenvironmentssuchasnetworkservers.Some tasks
may require exclusive accesstoshared resources.
The complementary term, single-user, is most commonly used when talking about an operating
system being usable only by one person at a time, or in reference to a single-user software
license agreement. Multi-user operating systems such as Unix sometimes have a single user
process available for emergency maintenance.
Multi User:-
Multi-userisa termthat definesan operatingsystem orapplicationsoftwarethatallowsconcurrent
access bymultiple usersof acomputer.Time-sharingsystemsare multi-usersystems.Most batch
processingsystemsformainframecomputers mayalsobe considered"multi-user",toavoidleavingthe
CPU idle while itwaitsforI/Ooperationstocomplete.However,the term"multitasking"ismore
commonin this context.
An example isaUNIXserverwhere multipleremote usershave access(suchasviaSecure Shell) tothe
Unix shell promptatthe same time.

14. Server:-
Definition:A network serverisa computerdesignedtoprocessrequestsanddeliverdatatoother
(client) computersoveralocal networkorthe Internet.
Definition:A serverisprimarilyaprogram that runson a machine,providingaparticularandspecific
service toothermachines connectedtothe machine onwhichitisfound.
At the mostbasic level,aserverisatechnologysolutionthat“serves”files,data,print,fax resources,
and more to multiple computers.
The word “server”oftenreferstothe specializedcomputer(orhardware) thatthe serversoftware runs
on.The serverisoptimizedtoperformservicesforothercomputersor“clients.”Clientscanbe
computersas well asprinters,faxes,orotherdevicesthatconnecttothe server.
Together, aserverand itsclientscompose aclient/servernetwork.A client/servernetworkprovides
routingsystemsandcentralizedaccesstoinformationandresources,storeddata,andmore.
Generallyspeaking,aserverisamachine witha specificsetof programsthat offerdifferenttypesof
service,whichothermachines(thencalledclients) requesttodocertaintasks.For example,afile server
isa machine whichkeepsfiles,andallowsclientstouploadanddownloadthemfromit.A webserveris
a machine that hostswebsitesandallowsInternetusers(clients)toaccessthese websites.The page
youare readingnowcomesfromthe about.comwebserver.A mail serverisamachine which,along
withthe storage and managementof email messages,providesservice toemail userswhocanread,
retrieve,andmanage these emailsmessages.

15. WorkStation:-
A workstation isa high-endmicrocomputerdesignedfortechnical orscientificapplications.Intended
primarilytobe usedbyone personata time,theyare commonlyconnectedtoalocal area network and
run multi-useroperatingsystems.The termworkstation hasalsobeenusedtorefertoa mainframe
computerterminal ora PC connectedtoa network.
Historically,workstationshadofferedhigherperformance than personal computers,especiallywith
respectto CPU andgraphics,memorycapacityand multitaskingcability.Theyare optimizedforthe
visualization andmanipulationof differenttypesof complex datasuchas3D mechanical design,
engineeringsimulation(e.g. computational fluiddynamics),animationandrenderingof images,and
mathematical plots.Consolesconsistof ahighresolutiondisplay,a keyboard andamouse at a
minimum,butalsooffermultipledisplays, graphicstablets,3Dmice (devicesformanipulatingand
navigating3D objectsandscenes),etc.Workstationsare the firstsegmentof the computermarketto
presentadvancedaccessoriesand collaborationtools.
A type of computerusedforengineeringapplications(CAD/CAM),desktoppublishing,software
development,andothertypesof applicationsthatrequireamoderate amountof computingpowerand
relativelyhighqualitygraphicscapabilities.
Workstationsgenerallycome withalarge,high-resolutiongraphicsscreen,atleast64 MB (megabytes)
of RAM, built-innetworksupport,andagraphical userinterface.
Client-Server Environment
Introduction to Client/Server Architecture
Numerousapplicationsrunina client/serverenvironment,thismeansthat clientcomputers(computers
forming part of the network) contact a server, generally a very powerful computer in terms of
input/output, which provides services to the client computers. These services are programmes which
provide data such as the time, files, a connection, etc.
The servicesare usedbyprograms clientprograms whichrun on client computers. This is why the term
"client" is applied (FTP client, email client, etc.), where a program is designed to run on a client
computer,capable of processingdatareceivedfromaserver(inthe case of the FTP clientwe are dealing
with files whereas for the email client we deal with email email).
Advantages of Client/Server Architecture
The client/servermodel isparticularlyrecommendedfornetworksrequiringahighdegree of reliability,
the main advantages being:

16.  centralisedresources: given that the server is the centre of the network, it can manage resources that
are common to all users, for example: a central database would be used to avoid problems caused by
redundant and inconsistent data
 improved security: as the number of entry points giving access to data is not so important
 server level administration: as clients do not play a major role in this model, they require less
administration
 scalable network: thanksto thisarchitecture itispossible toremove oraddclientswithoutaffectingthe
operation of the network and without the need for major modification
Disadvantages of the client/server model
Client/Server architecture also has the following drawbacks:
 increased cost: due to the technical complexity of the server
 a weaklink: the serveristhe onlyweaklinginthe client/server network, given that the entire network
is built around it! Fortunately, the server is highly fault tolerant (primarily thanks to the RAID system)
Client/Serversystemoperation
A client/server system operates as outlined in the following diagram:
 The client sends a request to the server using its IP address and the port, which is reserved for a
particular service running on the server.
 The server receives the request and responds using the client IP address and port.
What are static and dynamic websites?
There are many static websites on the Internet, you won’t be able to tell immediately if it is static, but
the chances are, if the site looks basic and is for a smaller company, and simply delivers information
without any bells and whistles, it could be a static website. Static websites can only really be updated
by someone with a knowledge of website development. Static websites are the cheapest to develop
and host, and many smaller companies still use these to get a web presence.
Advantages of static websites
 Quick to develop
 Cheap to develop
 Cheap to host

17. Disadvantages of static websites
 Requires web development expertise to update site
 Site not as useful for the user
 Content can get stagnant
Dynamic sites on the other hand can be more expensive to develop initially, but the advantages are
numerous. At a basic level, a dynamic website can give the website owner the ability to simply update
and add new content to the site. For example, news and events could be posted to the site through a
simple browser interface. Dynamic features of a site are only limited by imagination. Some examples
of dynamic website features could be: content management system, e-commerce system, bulletin /
discussion boards, intranet or extranet facilities, ability for clients or users to upload documents,
ability for administrators or users to create content or add information to a site (dynamic publishing).
Advantages of dynamic websites
 Much more functional website
 Much easier to update
 New content brings people back to the site and helps in the search engines
 Can work as a system to allow staff or users to collaborate
Disadvantages of dynamic websites
 Slower / more expensive to develop
 Hosting costs a little more
Active Page
A web page that is active, as in still being updated.
A web page that is dynamic - that is, there is some amount of programmatic behavior or interaction
with the user. Example - javascript code, ActiveX, applets, etc
Server-side scripting
Server-side scripting is a web server technology in which a user's request is verified by running a script
directly on the web server to generate dynamic web pages. It is usually used to provide interactive web
sites that interface to databases or other data stores. This is different from client-side scripting where
scripts are run by the viewing web browser, usually in JavaScript. The primary advantage to server-side
scripting is the ability to highly customize the response based on the user's requirements, access rights,
or queries into data stores.
From a security point of view, server-side scripts are never visible to the browser as these scripts are
executed on the server and emit HTML corresponding to user's input to the page.

18. When the server serves data in a commonly used manner, for example according to
the HTTP or FTP protocols, users may have their choice of a number of client programs (most modern
web browsers can request and receive data using both of those protocols). In the case of more
specialized applications, programmers may write their own server, client, and communications protocol,
that can only be used with one another.
Programs that run on a user's local computer without ever sending or receiving data over a network are
not considered clients, and so the operations of such programs would not be considered client-side
operations.
Some server-side scripting languages:-
 ASP
 C via CGI (*.c, *.csp)
 ColdFusion Markup Language (*.cfm)
 Java via JavaServer Pages (*.jsp)
 JavaScript using Server-side JavaScript (*.ssjs, *.js)
 Lua (*.lp *.op)
 Perl CGI (*.cgi, *.ipl, *.pl)
 PHP (*.php)
 Python via Django (*.py)
 Ruby, e.g. Ruby on Rails (open source)
 SMX (*.smx)
 Lasso (*.lasso)
 WebDNA (*.dna,*.tpl)
 Progress WebSpeed (*.r,*.w)
Client-side scripting
Client-side scripting generally refers to the class of computer programs on the web that
are executed client-side, by the user's web browser, instead of server-side (on the web server).[1] This
type of computer programming is an important part of the Dynamic HTML (DHTML) concept,
enabling web pages to be scripted; that is, to have different and changing content depending on user
input, environmental conditions (such as the time of day), or other variables.

19. Client-side scripts are often embedded within an HTML or XHTML document (hence known as an
"embedded script"), but they may also be contained in a separate file, which is referenced by the
document (or documents) that use it (hence known as an "external script"). Upon request, the necessary
files are sent to the user's computer by the web server (or servers) on which they reside. The user's web
browserexecutes the script, then displays the document, including any visible output from the script.
Client-side scripts may also contain instructions for the browser to follow in response to certain user
actions, (e.g., clicking a button). Often, these instructions can be followed without further communication
with the server.
By viewing the file that contains the script, users may be able to see its source code. Many web authors
learn how to write client-side scripts partly by examining the source code for other authors' scripts.
PHASE 1 – Analysis
This first phase is probably undertaken twice, first by you when you decide to develop a website for your
business. You need to justify that there is a role for a site within your business.
Secondly, by us, we will need to know such things as the target audience, primary and secondary . We
need to understand the aims of the site, what it is to achieve for your business. We need to understand
the purpose of the site, what is it going to do for your customers – current and potential.
An audit of your competitor’s websites will allow us to understand your market and how they market the
customers.
This knowledge will help us develop the requirements for your site.

20. PHASE 2 – Design
This phase is when we make the design decisions of how your site will look, and how it will work. From
our analysis we should have a good idea on your target audience. Now we are able to decide which
technologies are best suited for your company. Then we develop the user interface and navigation
system. Also, the site will be optimized for the average customer connectivity to the WEB and well as the
configuration of their computer system.
The personality, the look and feel of the website will also be established at this phase. This might be the
ideal time to think over your identity, logo and branding of your company. If you need to, we could bring in
Graphic Designers that would assist with a new image.
The bottom line is your primary requirements and we will focus on that issue.

21. PHASE 3 – Construction
Construction is often considered to be the project in its entirety his is not the case. Construction is the
phase where ideas and design come together and grow into your image. Pages are created, effects are
built in, images are produced, gateway scripts written and any other programming requirements are
produced. Obviously this is a time intensive part of the project; hence this must be done carefully because
it’s the backbone to the site.
Documentation is an important requirement, and the area no one enjoys to do, but without it the project
could no reflect the image to the customer you wish. This information you want to convey to your
customers must be the best, easiest to understand and concise so the customer gets the information in a
fashion they understand.
PHASE 4 – Testing
Testing phase of the project that is sometimes overlooked or considered expensive and therefore
reduced to the barest minimum. In any project there will be faults and bugs and they need to be
eliminated prior to production. We all want to make the best possible presentation to the customer;
therefore testing should be a must. In order to control expenses just the obvious errors will be correct and
the balance if any will be done as time goes by.
Testing has 2 primary phases, off-line and on-line.
 Off-line requires the developer to exercise each of the elements of the site, links, images etc.
while they are on the local computer, i.e. not connect to the Internet.
 On-line requires that a series of test are carried out to ensure that during the transfer nothing
was corrupted. Some elements can only be test while on-line. These test are conducted on a
separate system so the consumer doesn’t see it until the site has been completed.
Another test source could be using an outsource company to run tests prior to being on-line. These are
an additional expense and only recommend for extensive websites and have multi databases and unique
services.

22. PHASE 5 – Delivery
After our testing evaluation and most to the rough edges have been smoothed over as well as the
elements that allow the customers to interact with the site has been reviewed we’re ready for feed back.
The final process needs to be looked upon as a small project cycle in its’ own right. During this process
we then refine, implement and retest the changes and presto a new web presence will emerge.
Registration with the numerous search engines needs to be completed and tested as well. Keep in mind
that each search engine is different. Each search engine varies on its registration requirements and on
how long it takes to list a site so the consumer can locate it
PHASE 5 – Maintanence
Maintenance
Phase Six: Maintenance

23. The developmentof yourwebsite isnotnecessarilyover,though.One waytobringrepeatvisitorsto
your site isto offernewcontentorproductson a regularbasis.Most webdesignerswill be more than
happyto continue workingtogetherwithyou,toupdate the informationonyourwebsite.Many
designersoffermaintenance packagesatreducedrates,basedonhow oftenyouanticipate making
changesor additionstoyourwebsite.
If you prefertobe more handson,and update yourown content,there issomethingcalledaCMS
(ContentManagementSystem) thatcanbe implementedtoyourwebsite.Thisissomethingthatwould
be decideduponduringthe Planningstage.With aCMS, yourdesignerwill utilize onlinesoftwareto
developadatabase drivensite foryou.
A website drivenbyaCMS givesyouthe abilitytoeditthe contentareasof the website yourself.You
are givenaccesstoa back-endadministrativearea,where youcanuse an online texteditor(similartoa
mini versionof MicrosoftWord).You’ll be able toeditexistingcontentthisway,orif youare feeling
more adventurous,youcanevenaddnew pagesand contentyourself.The possibilitiesare endless!
It’sreallyupto you as far as howcomfortable youfeel asfaras updatingyourownwebsite.Some
people prefertohave all the control so that theycan make updatestotheirownwebsite the minute
theydecide todo so.Othersprefertohand off the website entirely,astheyhave enoughtaskson-hand
that are more importantforthemto handle directly.
That’s where the helpof ayour webdesignercomesin,once again,astheycan take overthe website
maintenance foryou – one lessthingforyou todo is alwaysa goodthinginthese busytimes!