web programming unit-ii 2 & 16 marks qa
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7/23/2019 Web Programming Unit-II 2 & 16 Marks QA
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Mailam Engineering College (Approved by AICTE, New Delhi, Affiliated to Anna University, Chennai
& Accredited by National Board of Accreditation (NBA, New Delhi
Mailam (Po), Villupuram (Dt). Pin: 604 304
DEPARTMET !" C!MP#TER APP$%CAT%!&
'e Programming MC*+3
UNIT II WORLD WIDE WEB
!verview " #eb $ec%rity, rivacy, and site'blocin) " A%dio and *ideo on the web "
Creatin) and +aintainin) the #eb " #eb site creation concepts " #eb a)e Editors "
!ptii-in) #eb .raphics " #eb A%dio /iles " /ors, Interactivity, and Database'Driven
#eb sites " /ile Transfer and downloadin) " /T " eer to eer " Downloadin) and
Installin) software0
+ Mar- /uetion it1 Aner
2. '1at o ou mean 'orl 'ie 'e5
### is a distrib%ted syste of inter lined pa)es that incl%de te1t, pict%res, so%ndand other inforation0 It enables easy access to the inforation available on the internet0
+. 'rite 1ort note on TTP52ttp is application protocol with the li)htness and speed necessary for
the distrib%ted collaborative hyperedia inforation syste0
3. '1at i "TP5
The basic Internet /ile Transfer rotocol0 /T, which is based on TC3I, enables thefetchin) and storin) of files between hosts on the Internet0
4. '1at i 7#%5.raphical User Interface0 4efers to the techni5%es involved in %sin) )raphics, alon)
with a eyboard and a o%se, to provide an easy'to'%se interface to soe pro)ra0
. '1at i #R$5U46 stands for Unifor 4eso%rce 6ocater0 Three are two types of U46
Absol%te U46 " This incl%de coplete path to the file location incl%din) all the naesof directories and s%b directories0
4elative U46 " These are lie shorthand that tells the browser to )o bacward one orore directories to find the file0
6. De8ine &CM$5
The $o%rce Code +ar%p 6an)%a)e ($C+6 is a forattin) lan)%a)e that can be%sed to create teplates for so%rce code that needs to be o%tp%t by /lic0
9. '1at i Mailing $it5
A )ro%p of %sers with a shared interest, whose e'ail address are ept in an
Prepared ByMs. A.Subathra Devi, Asst. Prof. / MCA
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electronic list that can be %sed to send e'ail to each eber on the list0
. '1at are t1e -e element in a proto;ol. 5
$ynta1 ' Incl%des data forat and $i)nal levels
$eantics " Incl%des control inforation for co'coordinatin) & Error handlin)
Tiin) " Incl%des speed atchin) and se5%encin)
*. '1at i TM$5
2yperte1t +ar%p 6an)%a)e0 This is a file forat, based on $.+6, for hyperte1tdoc%ents on the Internet0 It is very siple and allows for the ebeddin) of ia)es,so%nds, video streas, for fields and siple te1t forattin)0 4eferences to other ob7ectsare ebedded %sin) U46s0 2T+6 is a plain te1t file with coands 8+A49U TA.$: to tellthe web browsers how to display the file0
20. o o ou ;1ange t1e ;olor o8 a;-groun or te<t in TM$5
8body b)color;<=rr))bb<:8body te1t;<=ffffff< lin;<=ff>>>>< vlin;<=ff>>>>< alin;<=ff>>>><:
22. o o ou ue a pi;ture a t1e a;-groun in TM$58body bac)ro%nd;<b)ia)e07p)<:
2+. 6o0 3o 4ou a33 mu.i; to a 0e( page5
8ebed src;<yo%r%sicfile0id< a%tostart;<tr%e< loop;<tr%e< width;<?< hei)ht;<><:83ebed:
23. De8ine 'e &e;urit.
There are a lot of dan)ers in p%ttin) %p a #eb pa)e0 /ro invasions of privacy toact%al hacers cracin) yo%r sec%rity0 6earn how to sec%re yo%r #eb server and site as well
as hacs and patches to eep yo%rself safe0
24. '1at are t1e ne;eitie o8 uing TM$ 8orm5
.atherin) %ser inforation
Cond%ctin) $%rveys
Interactive services
2. '1at are t1e e=uen;e o8 tep 8or ea;1 TTP re=uet 8rom a ;lient to t1e
er>er5
+ain) the connection
+ain) a re5%est
The response
Closin) the connection
Define +I+E0
+I+E (+%ltip%rpose Internet +ail E1tensions is an open standard for sendin) %ltipart,%ltiedia data thro%)h Internet eail0
26. $it t1e pree8ine M%ME ;ontent tpe.
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Te1t
+%ltipart
+essa)e
Ia)e
A%dio
*ideo
+odel
Application
29. De8ine TM$.It is a siple pa)e description lan)%a)e, which enables doc%ent creation for the
web0
2. '1at i meant loop a;- are5A -one that enables the server to direct traffic to itself0 The host n%ber is alost
always @?0>0>0@0
2*. '1at i e 1oting5
#eb 2ostin) is a service that provides internet %sers with online cop%ter systesfor storin) inforation, ia)es, video, or any content accessible via the internet or web0 /orInternet %sers to view online inforation, the web hostin) copany places the website
pa)es (htl, php, etc files on a web server which is stored inside a data center0 Data
centers are connected to the internet with e1treely reliable hi)h speed connections so thatthe world has access to the web files ? ho%rs a day, days a wee0 #eb %sers access the
web pa)es thro%)h the websites I address or the websites doain nae0
+0. '1at i a e 1ot5A web host provider (or web host is the copany that hosts and aintains the web
server that stores the websites pa)es0
+2. Doe t1e e 1ot on m ite5No, the content that is within yo%r site is yo%rs and yo%rs alone
++. o mu;1 oe e 1oting ;ot5
#eb hostin) costs vary draatically dependin) on what type of website yo% plan onr%nnin), how any visitors the site receives, and any additional feat%res yo% ay re5%ire0
/or a siple site with htl, c)i, and php web pa)es, the pricin) can ran)e fro @F0>> peronth to %pward of G>0>> per onth for a virt%al web hostin) acco%nt0 If the website )ets
illions of visitors a day, yo% ay re5%ire a dedicated server which can cost anywherebetween @>>0>> per onth to F>>0>> per onth0 This fee is to aintain a reliable hi)h
speed connection and eno%)h bandwidth or data transfer per onth for the website %sers toeffective navi)ate thro%)h the website0
+3. Can % 1ot m eite mel85Hes0 Its preferable to have a hi)h speed connection to the internet (D$6, Cable, or
T@ and yo% can dedicate one cop%ter to be a web server0 Also, the internet provider ayinc%r an e1tra char)e for hostin)0
2owever, this is the least efficient web hostin) ethod since it p%ts heavy additionalre5%ireents on yo%r hoe or office internet connection line and e1poses yo% to sec%rity
riss0 It is iportant to note that the cop%ter dedicated to bein) a web server %streain on ? ho%rs a day, days a wee for the website to be online all the tie0
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+4. o o % tran8er m eite 8ile 8rom m lo;al ;omputer to t1e remote e1oting er>er5
The ost coon ethod to %pload files fro a local cop%ter to yo%r web hostin)server is by %sin) an /T, or /ile Transfer rotocol, client0 An /T client is a piece of software
that allows a %ser to a%thenticate and establish a connection to the reote web hostin)server to %pload files for the website0
+. '1at i anit1 or ata tran8er5
Bandwidth or data transfer are ters referrin) to the ao%nt of data that can betransferred in and o%t within a )iven period of tie, %s%ally onthly0 #hen a visitor
browses a website, he or she has to download the 2T+6, ia)es, scripts and other files toview the web pa)e0 The ao%nt of transfer the visitor %ses co%nts towards yo%r allocated
onthly ao%nt of data transfer0 /or e1aple, if the visitor retrieves an ia)e that is ?9Band one 2T+6 pa)e at 9B, then the total data transfer for that session is appro1iately
9B0
+6. '1at i i- pa;e or torage pa;e5Dis space or stora)e space refers to the ao%nt of space yo% are allowed to store in
yo%r web hostin) acco%nt0 #hen yo% %pload website files, for e1aple, 2T+6 pa)es,ia)es, )raphics, scripts and so forth, it taes %p space on the web servers hard drive(s0
The si-e of the files yo% %pload into yo%r web hostin) will respectively deterine how %chstora)e space yo% will %se %p0
+9. o mu;1 i- pa;e an anit1 o % nee 8or 1oting m e ite5There is no definite answer for this 5%estion since it is hi)hly dependent on yo%r
c%rrent and f%t%re web hostin) needs for the website in 5%estion0 2owever, a sall personalwebsite with li)ht traffic will re5%ire F> ' @>> +B of stora)e space (dis space and @ .B of
onthly data transfer0 JIC Desi)n offers a $tarter #eb 2ostin) lan s%itable for this type of
website0 2owever, if the website offers videos or lar)e resol%tion ia)es, the Advanced #eb2ostin) lan is a possibility0
+. o o % get m on omain name5
Its iportant to reali-e that doain re)istration is separate fro web hostin) andthese two services can be provided by two different copanies0 A doain nae can be
re)istered with any ICANN'approved doain re)istrar0 JIC Desi)n offers doain naere)istrations and incl%des a doain nae free with specific web hostin) plans0
29. How do I get started developing a Web site?Ho%r #eb sites p%rpose i)ht be, for e1aple, <to sell o%r line of prod%cts0< A )ood
p%rpose will be specific and represent a new activity that adds si)nificant val%e to the #eb0
Then state specific, eas%rable ob7ectives that the site sho%ld accoplish0
30. '1at i t1e mot ;ommon mita-e 'e e>eloper ma-e5A lac of %nderstandin) of the a%dience for the #eb site0 Understandin) yo%r a%dience
eans nowin) their needs and e1pectations0 /or e1aple, a coon error is when soesites that depend on an in'person visit ne)lect to identify the city and state in which the
store or physical event is located0 The developers for)et that the #eb site is )lobal0Another coon a%dience error is to ass%e that they now abo%t the navi)ation
c%es on a site0 2avin) sybols, lins on certain words, and odes of representin) theinforation based on clicin) on lins aes a site hard to navi)ate0 The a%dience needs to
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be able to find o%t the navi)ation schee of a site0 Ideally, the schee sho%ld be self'evident, even to a brand new %ser0
32. '1at 1oul % loo- 8or in a 'e e>eloper (or agen;) % mig1t 1ire5
As the developers, <2ow can o%r needs be et with #eb'based co%nicationK< If the developers can artic%late iss%es s%ch as identifyin) yo%r a%dience, eetin) their needs,
and tain) advanta)e of the %ni5%e 5%alities of the #eb for yo%r #ebs p%rpose, considersthe0 If the developers start blabbin) on abo%t technolo)y''how cool Javascript (or fraes,
D2T+6 is for e1aple''dont hire the0
3+. '1at i t1e i88eren;e eteen ?'e e>elopment? an ?'e eign.?#eb developent encopasses a whole set of processes, and one of those
processes is #eb desi)n0 #eb desi)n, %nfort%nately, has coe to represent only pa)e layo%tand )raphics iss%es0
#eb desi)n as encopassin) far ore than that''incl%din) iss%es s%ch as hyperte1t
navi)ation, theatic iss%es that have to do with the #ebs p%rpose, and or)ani-ational
iss%es abo%t the #eb sites file or)ani-ation0 I hope people who call theselves <#ebdesi)ners< %nderstand this, b%t I thin any do not0
33. '1at o ou t1in- are t1e et 'e ite5Those that %nabashedly foc%s on their p%rpose and have a stron) sense of their
a%dience0 Hahoo0cos f%ll covera)e news area is absol%tely fantastic''it accoplishes aspecific p%rpose %sin) the %ni5%e 5%alities of the #ebL it has a clean layo%t and
or)ani-ation0
34. '1at i meant ;oo-ie5A essa)e )iven to a #eb browser by a #eb server0 The browser stores the essa)e
in a te1t file0 The essa)e is then sent bac to the server each tie the browser re5%ests apa)e fro the server0
3. '1at are t1e a>antage o8 uing ;oo-ie5 cooies do not re5%ire any server reso%rces0
cooies are easy to ipleent0
yo% can confi)%re cooies and e1pire when the browser ends0
36. '1at oe @M$ tan 8or5In cop%ter lin)o M+6 stands for E1tensible +ar%p 6an)%a)e0 It is a te1t%al data
forat and is %sed in interchan)in) data over the Internet0 M+6'based forats havebecoe the defa%lt for ost office'prod%ctivity tools, incl%din) +icrosoft !ffice,
!pen!ffice0or), and Apples i#or0
39. 'rite ome a>antage o8 @M$.
It is a platfor independent lan)%a)e0
It is as easy as 2T+60
M+6 is f%lly copatible with applications lie JA*A, and it can be cobined with any
application which is capable of processin) M+6 irrespective of the platfor it is bein)%sed on0
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M+6 is an e1treely portable lan)%a)e to the e1tent that it can be %sed on lar)e
networs with %ltiple platfors lie the internet, and it can be %sed on handhelds
or paltops or DAs0
M+6 is an e1tendable lan)%a)e, eanin) that yo% can create yo%r own ta)s, or %se
the ta)s which have already been created0 It can be deployed on any networ if it is aicable for %sa)e with the application in
%se0 If the application can wor alon) with M+6, then M+6 can wor on any platfor and
has no bo%ndaries0 It is also vendor independent and syste independent0 #hile data is bein)
e1chan)ed %sin) M+6, there will be no loss of data even between systes that %setotally different forats0
3. '1at o ou nee to e;ome a 1a;-er5E1stensive nowled)e of cop%ter and software sec%rity, lots of pro)rain) sills,
and in)en%ity0
3*. '1at are t1e A>antage Dia>antage o8 real time pro;eing at;1
pro;eing5 Advantages of Real Time processing
The syste is iediately %pdated0
There will be (in ost cases no processin) la) ca%sed by the syste0
Disadvantages Of Real Time Processing
The syste %st always be online0
Advantages of batch processing It allows sharin) of cop%ter reso%rces aon) any %sers0
It shifts the tie of 7ob processin) to when the cop%tin) reso%rces are less b%sy0
It avoids idlin) of cop%tin) reso%rces with in%te'by'in%te h%an interaction and
s%pervision0
Disadvantages
It is diffic%lt to provide the desired priority sched%lin)0
40. '1at i a 'e ire;tor5
Basically web directory is a site where we can s%bit and fetch lin on the basis of their cate)ories0 Is a stron) edi% of ain) bacward lins0 Us%ally ppl )ot conf%sed in
search en)ine and in web directory both is different0 There is no siilarity between the0/or E1aple'http33www0)oo)le0co is a search en)ine and http33www0lins)allery0info is
a web directory0
42. o o ou get to lo;-e eite5
There are specific websites that help bypass websites0 2owever, soe websites dontreally wor or the effect doesnt really tae place0 There are ways s%ch as %nlocin)parental controls and editin) it or )oin) onto websites that allow to bypass areas where
yo%re not allowed to )o to0 yo% co%ld try either of the
4+. o o ou impro>e t1e >iiilit o8 a eite5
Apply $E! for the website so that it will create bac lins0 roote it the socialedia sites0
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43. o o ou ;reate an Animate %mage or &lie1o5
This can be done very easily in Java$cript %sin) the set interval coand and other
piece of code in order to reprod%ce the 2T+6 code therefore creatin) a slideshow0Dynaic Drive has a pa)e on this with open so%rce scripts yo% can %se0 Ive added a lin
%nder related lins0
44. '1at i i88eren;e eteen element an attriute in @M$5Eleents are %sed to encaps%late pieces of data, and attrib%tes are )enerally %sed to
provide accopanyin) inforation abo%t an eleent, rather than to encaps%late raw dataitself0
4. o o ou ;reate an @M$ o;ument5
!pen +icrosoft e1cel, then do yo%r wor etc, then )o to save as than clic save as1l doc%ent0 Ho% can %se any basic te1t editor to create or with 1l files, for e1aple
notepad can be %sed to create and edit 1l files0 Ho% can also %se a dedicated 1l editor to
achieve the sae and to also carry o%t e1tra tass lie validation and bindin)0
46. '1at i Dataae Dri>en 'e page5
!ne of the ost coon types of dynaic web pa)es is the database driven type0This eans that yo% have a web pa)e that )rabs inforation fro a database and inserts
that inforation into the web pa)e each tie it is loaded0
If the inforation stored in the database chan)es, the web pa)e connected to the
database will also chan)e accordin)ly (and a%toatically, witho%t h%an intervention0
49. De8ine 'e Broer
A web browser displays a web doc%ent and enables %sers to access webdoc%ents0 #hen the %ser clics a hyperlin, the browser initiates a essa)e to a web
server0 This essa)e re5%ests the server to retrieve the re5%ested inforation and send itbac to the web browser thro%)h the teleco%nications networ0
4. '1at i meant PeertoPeer5A peer'to'peer cop%ter networ is one in which each cop%ter in the networ can
act as a client or server for the other cop%ters in the networ, allowin) shared access tovario%s reso%rces s%ch as files, peripherals, and sensors witho%t the need for a centralserver0
4*. o Doe %nternet P+P 'or-5The %ser %st first download and e1ec%te a peer'to'peer networin) pro)ra0 After
la%nchin) the pro)ra, the %ser enters the I address of another cop%ter belon)in) to thenetwor0 !nce the cop%ter finds another networ eber on'line, it will connect to that%sers connection0
0. o oe auio an >ieo e88e;t to eite5 #/ o>De; +020F
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There are any cop%ter forats for so%nd, and theoretically any of the co%ld be %sed ina web pa)e0 The three ost pop%lar forats (those ost liely to wor on yo%r readers
achines are #A*E, AU, and +IDI0
#A*E ('a>efor A%dio /ile /orat, with the file e1tension 0wav was invented for
#indows by +icrosoft0 AU (Audio /ile /orat, file e1tension 0a% was invented by NeMT and
$%n0 Both are now widely accepted on any platfors, and are coon on web pa)es0#A*E and AU are lie so%nd recordin)s000 they reprod%ce recorded so%nds (or cop%ter)enerated so%nds0 They also tend to be bi) files for 7%st a little so%nd0 #A*E and AU files
are )ood for a short so%nd effect s%ch as a short )reetin) or perhaps a cow oo0 There isalso a recorded so%nd forat called AI// (A%dio %nterchan)e "ile "orat, invented by
Apple and $.I, which is widely s%pported, b%t is far less pop%lar than AU and #A*E0
Vieo on t1e 'e
Today, ost videos are shown thro%)h a pl%)'in (lie flash0 2owever, differentbrowsers ay have different pl%)'ins0 2T+6 defines a new eleent which specifies a
standard way to ebed a video3ovie on a web pa)e the 8video: eleent0
8video width;<G?>< hei)ht;<?>< controls;<controls<:8so%rce src;<ovie0p< type;<video3p<:8so%rce src;<ovie0o))< type;<video3o))<:83video:
2. 1at i ataae ri>en eite, 1o t1e uilt5 #/ o>De; +020FA database'driven website is a website that %ses a database to )ather, display, or
anip%late inforation0 The web pa)es that are created when a database website desi)nsol%tion is %sed are act%ally called <dynaic web pa)es< as opposed to <static< web pa)es0
The inforation contained in the database is %s%ally ept %p to date by %sin) a websitecontent ana)eent syste0 The content ana)eent syste can be desi)ned and
tailored to yo%r specific re5%ireents0
Database driven sites can be b%ilt %sin) several copetin) technolo)ies, each with itOs own
advanta)es0 $oe of those technolo)ies3tools incl%de
2
J$
A$
E46
Cold /%sion
+. '1at i a p1i1ing e ite5 #/ o>De; +022F
hishin) is atteptin) to ac5%ire inforation s%ch as %sernaes, passwords, andcredit card details by as5%eradin) as a tr%stworthy entity in an electronic co%nication0Co%nications p%rportin) to be fro pop%lar social web sites, a%ction sites, onlinepayent processors or IT adinistrators are coonly %sed to l%re the %ns%spectin)p%blic0 hishin) eails ay contain lins to websites that are infected with alware0hishin) is typically carried o%t by e'ail spoofin) or instant essa)in), and it often directs%sers to enter details at a fae website whose loo and feel are alost identical to thele)itiate one
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3. o to re;ogniGe p1i1ing email meage, lin-, or p1one ;all
hishin) eail essa)es, websites, and phone calls are desi)ned to steal oney0
Cybercriinals can do this by installin) alicio%s software on yo%r cop%ter or stealin)personal inforation off of yo%r cop%ter0
Cybercriinals also %se social en)ineerin) to convince yo% to install alicio%ssoftware or hand over yo%r personal inforation %nder false pretenses0 They i)ht eail
yo%, call yo% on the phone, or convince yo% to download soethin) off of a website0
4. '1at oe a p1i1ing email meage loo- li-e5
2ere is an e1aple of what a phishin) sca in an eail essa)e i)ht loo lie0
. '1at i t1e tpi;al ataae te;1nologie ue 8or running a ataae ri>eneite5 #/ o>De; +022F
+$ $P6 $erver or !racle for hi)h traffic database'driven web sites0
+y$P6 for low'cost database'access0
+$ Access for low traffic web sites0
Part B
2. E<plain t1e 'orl 'ie 'e Con;ept in etail.
The Hypertext Concept
• The hyperte1t is a way of presentin) inforation in s%ch a way
that the se5%ence of the inforation is left %p to the reader0
• This se5%ence is %s%ally non'linear, however readers can follow
a linear se5%ence0
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• The hyperte1t wors by eans of hyperlin, which are
hi)hli)hted or %nderlined words (or )raphics that one can clic to brin) another
doc%ent into view0
Web Broser
• A web browser displays a web doc%ent and enables %sers to access web
doc%ents0
• #hen the %ser clics a hyperlin, the browser initiates a essa)e to a web
server0
• This essa)e re5%ests the server to retrieve the re5%ested inforation and send
it bac to the web browser thro%)h the teleco%nications networ0
#eb $erver
•
This is a pro)ra that waits patiently for the browser to re5%est a web pa)e0
• The server loos for the re5%ested inforation, retrieves it and sends it to the
browser or sends an error essa)e if the file is not fo%nd0
!niform Reso"rce #ocators $!R#% and Transfer protocols
These are the web addresses0
• The reso%rce locator is an addressin) syste that precisely states where a
reso%rce is located0
• It is divided into fo%r parts protocolL server3 doain naeL path and thereso%rce nae0 e) http33www0cites0%i%c0ed%3@>@3%rl@>@0htl
• The first portion of the U46 (http desi)nates the protocol that is %sed to locate
the file or reso%rce on the #eb0
• A protocol is a standardi-ed eans of co%nication aon) achines across a
networ0 rotocols allow data to be taen apart for faster transission,
transitted, and then reassebled at the destination in the correct order0
• 2ere, http represents the HyperText Transfer Protocol , which is %sed to transfer
#eb pa)es across the Internet to #eb browsers s%ch as Netscape Navi)ator,Internet E1plorer, or 6yn10
• The portion of the U46 followin) the protocol (www0cites0%i%c0ed% desi)nates the
host nae of the cop%ter yo% are accessin)0 The desi)nator www, fo%nd in
any U46s, is an acrony for #orld #ide #eb0 #hile %sin) www is conventional,it is not necessary0 $oe #eb servers oit the need to type www0
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• A U46 ay have any n%ber of directories followin) it0 In this e1aple, @>@ is a
directory %nder the root directory of the host yo% are accessin)0 The file
%rl@>@0htl is located in the @>@ directory0
+. '1at are 'e $anguage t1at are ue to ;reate e ite in etail5
HT&# $HyperText &ar'"p #ang"age%
• It is the %niversal lan)%a)e %nderstood by all ### (#orld #ide #eb clients0
• An 2T+6 doc%ent (pro)ra is A$CII te1t with ebedded instr%ctions
(ar%ps which affect the way the te1t is displayed0
• The basic odel for 2T+6 e1ec%tion is to fetch a doc%ent by its nae (e0)0 U46,
interpret the 2T+6 and display the doc%ent, possibly fetchin) additional 2T+6 doc%ents
in the process0
•
It can accept %ser inp%t and3or ca%se additional 2T+6 doc%ents to be fetched byU460
• rovidin) safety, platfor independence, and the ability to interact with a variety of
forats, protocols, tools, and lan)%a)es aes it a %niversal lan)%a)e0
(ava and (ava )cript
• Java is a lan)%a)e for sendin) applets over the web, so that the cop%ter can
e1ec%te the0
• Java$cript is a lan)%a)e that allows 2T+6 to ebed sall pro)ras called scripts
in web pa)es0
• The ain p%rpose of applets and scripts is to speed %p web pa)e interactivity0
*B$cript and ActiveM Controls
• *Bscript resebles +icrosoftOs *is%al Basic and is %sed to add scripts to pa)es
that are displayed by Internet e1plorer0
• ActiveM controls, lie Java, are %sed to ebed e1ec%table pro)ras into a web
pa)e0
*&#
• M+6 stands for EMtensible +ar%p 6an)%a)e
• M+6 is a ar%p lan)%a)e %ch lie 2T+6
• M+6 was desi)ned to carry data, not to display data
• M+6 ta)s are not predefined0 #e %st define o%r own ta)s
• M+6 is desi)ned to be self'descriptive
• M+6 is a #GC 4ecoendation0
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• M+6 is not a replaceent for 2T+60 M+6 and 2T+6 were desi)ned with different
)oals0 M+6 was desi)ned to transport and store data, with foc%s on what data is0
• 2T+6 was desi)ned to display data, with foc%s on how data loos0 2T+6 is abo%t
displayin) inforation, while M+6 is abo%t carryin) inforation0
• #ith M+6 we invent o%r !wn Ta)s0 The ta)s in the e1aple below (lie 8to: and
8fro: are not defined in any M+6 standard0
8note:
8to:Tove83to:
8fro:Jani83fro:
8headin):4einder83headin):
8body:Dont for)et e this weeend83body:
8note:
• These ta)s are <invented< by the a%thor of the M+6 doc%ent0 That is beca%se
the M+6 lan)%a)e has no predefined ta)s0
• The ta)s %sed in 2T+6 (and the str%ct%re of 2T+6 are predefined0 2T+6
doc%ents can only %se ta)s defined in the 2T+6 standard (lie 8p:, 8h@:,
etc00 M+6 allows the a%thor to define his own ta)s and his own doc%entstr%ct%re0
Portals
• A portal is a web site that wants to be the start pa)e0
• A portal site incl%des web )%ides, search en)ines, chat roos, e'ail acco%nts
and news services0
• All portal services are free b%t soe re5%ires re)isterin) and choosin) a
password0
• Corporations are replacin) their internal hoepa)es with portals0
Web directories and )earch +ngines
• A web directory or lin directory is a directory on the #orld #ide #eb0
• It speciali-es in linin) to other web sites and cate)ori-in) those lins0
• A web directory is not a search en)ine, and does not display lists of web pa)es
based on eywords, instead it lists web sites by cate)ory and s%bcate)ory0 Thecate)ori-ation is %s%ally based on the whole web site, rather than one pa)e or a
set of eywords, and sites are often liited to incl%sion in only one or twocate)ories0
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• #eb directories often allow site owners to directly s%bit their site for incl%sion,
and have editors review s%bissions for fitness0
• A #eb search en)ine is a search en)ine desi)ned to search for inforation on the
#orld #ide #eb0
• Inforation ay consist of web pa)es, ia)es and other types of files0 $oe
search en)ines also ine data available in news)ro%ps, databases, or open
directories0
• Unlie #eb directories, which are aintained by h%an editors, search en)ines
operate al)orithically or are a i1t%re of al)orithic and h%an inp%t0
• A search en)ine operates, in the followin) order
@0 #eb crawlin)
?0 Inde1in)
G0 $earchin)
• #eb search en)ines wor by storin) inforation abo%t any web pa)es, which
they retrieve fro the ### itself0 These pa)es are retrieved by a #eb crawlerQ
an a%toated #eb browser which follows every lin it sees0
• #hen a %ser enters a 5%ery into a search en)ine (typically by %sin) ey words,
the en)ine e1aines its inde1 and provides a listin) of best'atchin) web pa)esaccordin) to its criteria, %s%ally with a short s%ary containin) the doc%ents
title and soeties parts of the te1t0
• +ost search en)ines s%pport the %se of the boolean operators AND, !4 and N!T
to f%rther specify the search 5%ery0 $oe search en)ines provide an advanced
feat%re called pro1iity search which allows %sers to define the distance between
eywords0
Home Pages
• The hoepa)e or ain pa)e is the U46 or local file that a%toatically loads when a
web browser starts and when the browsers <hoe< b%tton is pressed0
• The ter is also %sed to refer to the front pa)e, webserver directory inde1, or ain
web pa)e of a website of a )ro%p, copany, or)ani-ation, or individ%al0
• In soe co%ntries, s%ch as .erany, Japan, and $o%th 9orea, and forerly in the
U$, the ter <hoepa)e< coonly refers to a coplete website (of a copany or
other or)ani-ation rather than to a sin)le web pa)e0
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• Also, with ore and ore people nowin) how to navi)ate the internet easily, the
si)nificance of choosin) a hoepa)e is alost non'e1istent0
• +any software copanies now a%toatically set their copanys website as the
%sers hoepa)e0
3. Di;u aout 'e &e;urit, Pri>a;, an &iteBlo;-ing
Web )ec"rity and Privacy Concepts
• $tand'alone cop%ters have $ec%rity olicy associated with the that can be
odified by %sers with the appropriate ri)hts0
• #hen a cop%ter 7oins a doain, the doain $ec%rity olicy is applied to the local
cop%ter0
• Doain $ec%rity olicy will override any chan)es ade to $ec%rity olicy at the
destop level0
• #eb sec%rity defines what the browser will allow web pa)es to r%n or store on the
cop%ter0
• Browsers have sec%rity policies, or systes that enable %s to specify which web sites
can tae what types of actions on o%r cop%ter0
• Another aspect of web sec%rity specifies what inforation web sites can store on the
cop%ter, to trac o%r %se of the web site0
Cooies
• Cooies are essa)es that web servers pass to the web browser when we visit
Internet sites0
• The browser stores each essa)e in a sall file, called cooie0t1t0
• #hen we re5%est another pa)e fro the server, the browser sends the cooie bac to
the server0
• These files typically contain inforation abo%t o%r visit to the web pa)e, as well as
any inforation weve vol%nteered, s%ch as the nae and interests0
• Cooies are ost coonly %sed to trac web site activity0 #hen we visit soe sites,
the server )ives a cooie that acts as the identification card0 Upon each ret%rn visitto that site, the browser passes that cooie bac to the server0
• In this way, a web server can )ather inforation abo%t which web pa)es are %sed the
ost, and which pa)es are )atherin) the ost repeat hits0
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• Cooies are also %sed for online shoppin)0 !nline stores often %se cooies that record
any personal inforation we enter, as well as any ites in the electronic shoppin)
cart, so that %ser dont need to re'enter this inforation each tie we visit the site0
• $ervers also %se cooies to provide personali-ed web pa)es0 #hen we select
preferences at a site that %ses this option, the server places the inforation in a
cooie0 #hen we ret%rn, the server %ses the inforation in the cooie to create ac%stoi-ed pa)e for %s0
)ec"rity concerns in coo'ies
!nly the web site that creates a cooie can read it0 Additionally, web servers can%se only inforation that yo% provide or choices that yo% ae while visitin) the
web site as content in cooies0
Acceptin) a cooie does not )ive a server access to the cop%ter or any of the
personal inforation (e1cept for any inforation that we ay have p%rposely )iven,as with online shoppin)0 $ervers can read only cooies that they have set, so otherservers do not have access to the inforation0 Also, it is not possible to e1ec%te code
fro a cooie, and not possible to %se a cooie to deliver a vir%s0
latfor for Internet Content $election (IC$
• The IC$ specification enables labels (etadata to be associated with Internet
content0
• It was ori)inally desi)ned to help parents and teachers control what children
access on the Internet, b%t it also facilitates other %ses for labels, incl%din) code
si)nin) and privacy0
• The IC$ platfor is one on which other ratin) services and filterin) software has
been b%ilt0
• IC$ is a cross'ind%stry worin) )ro%p whose )oal is to facilitate the
developent of technolo)ies to )ive %sers of interactive edia, s%ch as theInternet, control over the inds of aterial to which they and their children have
access0
• IC$ ebers believe that individ%als, )ro%ps and b%sinesses sho%ld have easy
access to the widest possible ran)e of content selection prod%cts, and a diversity
of vol%ntary ratin) systes0
• In order to advance its )oals, IC$ will devise a set of standards that facilitate
the followin)
o $elf'ratin) Enable content providers to vol%ntarily label the content they create and
distrib%te0
o Third'party ratin) Enable %ltiple, independent labelin) services to associate
additional labels with content created and distrib%ted by others0 $ervices ay devise
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their own labelin) systes, and the sae content ay receive different labels frodifferent services0
o Ease'of'%se Enable parents and teachers to %se ratin)s and labels fro a diversity
of so%rces to control the inforation that children %nder their s%pervision receive0
Content,Rating )ervices- )afes"rf and R)AC $Recreational )otare Advisory Co"ncil%
• The two ratin) systes that are b%ilt into Netscape Netwatch are $afes%rf andthe 4ecreational $oftware Advisory0
• +icrosoftOs Content Advisor incl%des only 4$ACOs syste0
• $afes%rf is a parentsO )ro%p tryin) to ae the internet a safe and %sef%l tool for
children0
• 4$AC is a nonprofit corporation and its ission was to iss%e a ratin) syste for
cop%ter )aes, and it later e1tended its )ae'ratin) syste to the Internet0
4. Di;u 1o Auio an >ieo on t1e e.
#ith the increased pop%larity of broadband connections, any sites feat%res %sic,
ovie, and television clips which can be viewed or download0
2owever the a%dio or video files are lar)e in si-e and tae a lon) tie to download0
$ince a%dio and video files are lar)e, streain) was invented0
$treain) enables the cop%ter to play the be)innin) of an a%dio or video file while
the rest of the file is still downloadin)0
If the file arrives ore slowly than the cop%ter plays it, the playbac has )apswhile the cop%ter waits for ore data to play0
Popular Audio and Video players
4eal!ne layer " plays ost pop%lar a%dio forats and video files, incl%din)
streain) a%dio and video0 $%pports b%rnin) a%dio files on CDs, so we can createo%r own %sic CDs0
P%ic Tie " plays a%dio and video files stored in the P%ictie forat0
#indows +edia layer " plays both re)%lar and streain) a%dio and video files,
incl%din) ost a%dio files and CDs0 It s%pports b%rnin) to CDs or copyin) files toportable edia players that s%pport #+A forat0
#inAp " plays +G and windows edia files, as well as any other pop%lar %sic
forats, CDs, and streain) a%dio0
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+%sic+atch " plays +Gs and CDs, copies and creates CDs, transfers +Gs to
portable edia players, and s%pports internet radio broadcasts0
Playing video on the Internet
The video files are very lar)e in si-e, eanin) a video clip 7%st a few seconds lon)
co%ld tae ten in%tes or ore to download0
Even %sin) streain) edia, where the content is played as it is downloaded, the
ia)es were often blocy and tiny0
#ith iproved video copression techni5%es and faster internet connections the rich
%ltiedia content can be downloaded or played within seconds0
rerecorded video
o $everal video forats are in %se on the internet0
o +any videos play in windows edia player, whereas other videos re5%ire
4eal!ne player or P%ictie player0
o #e can view the prerecorded video clips %sin) the ri)ht player0
6ive video with webcas
o Another so%rce for video broadcasts is the ever'pop%lar webca0
o These are di)ital video caeras broadcast fro a specific location
o #ebca ia)es are %s%ally %pdated between every few seconds,
altho%)h soe sites %se streain) video for their webcas0
. '1at are t1e tep 8or 'e ite Creation5
Basic steps in creating a site
lan the str%ct%re of the site, so that we have an idea what inforation will be on at
least the hoe pa)e and other ey pa)es0
Usin) the te1t editor or web pa)e editor, create the pa)es of the site and save the
as 2T+6 files0 Use a )raphics editor to create or view )raphics for the pa)es0
Usin) browser, view the 2T+6 files created0 Chec the contents and the lins
%blish the web site by p%ttin) all of its files on a web server0
Usin) the browser, view the web pa)es as stored on the web server0
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%blici-e the site, )et feedbac, )et new ideas, and repeat the steps0
Planning the )ite
The plannin) process involves answerin) these 5%estions0
#ho is the a%dience for the siteK
#hat can yo% p%t on the site that will interest peopleK
2ow can we ae it easy for people to navi)ate the siteK
2ow the pa)es are stored on the siteK
#hat are the tools needed to develop the siteK
.ss"es to be aare of hen planning the eb site-
Te1t si-e
Colors
#ritin) for an international a%dience
rivacy
+aintenance
Accessibility
Tools needed to develop the site
Te1t
ict%res
Aniated )raphics
A%dio files
*ideo files
Aniation files
/ora and database inforation
Te1t editor
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Drawin) pro)ras
Clip art )allery
$o%nd or video e5%ipent
6. Brie8l i;u aout !ptimiGing e grap1i; an it 8ile 8ormat.
/raphics 0ile formats
*ector ia)es consist if lines and vario%s shapes o%tlined and filled with colors or
shadin)s0
Bitap ia)es consist of colored dots, or pi1els0 #eb doc%ents coonly %se
bitap ia)es in two forats .raphics Interchan)e /orat (.I/ and Jointhoto)raphic E1perts .ro%p (JE.0
Common programs for creating /.0 and (P+/ files
.enerally, .raphics pro)ras are of three varieties
aint and photo pro)ras " Enables to read different ia)e files and c%stoi-e the
for web %se0 E) Adobe hotoshop and +acroedia firewors
Ill%stration pro)ras " foc%s on creatin) ia)es, principally vector )raphics and
have feat%res for optii-in) the bitap files0 E) Adobe Ill%strator and CorelDraw0
.raphics Utilities ' sall pro)ras with siple feat%res that foc%s on convertin)
ia)es fro one forat to another0
/raphics program that are idely available-
+icrosoft aint
Adobe hoto$hop
Adobe Ia)e4eady
+acroedia /irewors
aint $hop ro
6view pro
Optimi1ing .mages
The Best ethod to decrease file si-e for a #EB ia)e is to decrease the 5%ality0
This does N!T ean the ia)e will not loo )ood on a cop%ter onitor0
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Di)iti-ed ia)es are norally at a %ch hi)her 5%ality (resol%tion 3 dots per inch
than a onitor can display0
This step alone will norally red%ce the file si-e to @3F of the ori)inal0 hysical si-e
will not chan)e (Avoid resi-e %ntil final step0
The $econd best ethod (optional is to crop off any dead area0 /or e1aple,
center the s%b7ect in the pict%re by croppin) the borders0
Usin) resi-e to red%ce file si-e is N!T very effective0 (%s%ally no ore than @3? of
the ori)inal si-e ' even if we tae the viewin) si-e below G?> 1 ?> ( 4esi-e sho%ld
be %sed to obtain the physical si-e yo% desire i0e resi-in) ' Used alone res%lts in ania)e that is not really optii-ed very well0
+inii-e the ia)e diensions by %sin) the sallest practical ia)e hei)ht and
width0
+inii-in) or avoidin) certail types of Ia)e content0
+inii-in) and flattenin) colors0
0 #hat is /T, and how do I %se it to transfer filesK RUP Nov3Dec ?>@>&?>@@S
/ile Transfer rotocol (/T is a networ protocol %sed to transfer data fro one
cop%ter to another thro%)h a networ, s%ch as the Internet0
/T is a file transfer protocol for e1chan)in) and anip%latin) files over any TC'basedcop%ter networ0 A /T client ay connect to a /T server to anip%late files on that
server0 As there are any /T client and server pro)ras available for different operatin)systes, /T is a pop%lar choice for e1chan)in) files independent of the operatin) systes
involved0
Connection methods
/T r%ns e1cl%sively over TC0 /T servers by defa%lt listen on port ?@ for incoin)
connections fro /T clients0 A connection to this port fro the /T Client fors the controlstrea on which coands are passed to the /T server fro the /T client and on
occasion fro the /T server to the /T client0 /T %ses o%t'of'band control, which eans it%ses a separate connection for control and data0 Th%s, for the act%al file transfer to tae
place, a different connection is re5%ired which is called the data strea0 Dependin) on the
transfer ode, the process of settin) %p the data strea is different0
In active ode, the /T client opens a dynaic port (@F?"FFGF, sends the /T
server the dynaic port n%ber on which it is listenin) over the control strea and waitsfor a connection fro the /T server0 #hen the /T server initiates the data connection to
the /T client it binds the so%rce port to port ?> on the /T server0
In order to %se active ode, the client sends a !4T coand, with the I and port as
ar)%ent0 The forat for the I and port is <h@,h?,hG,h,p@,p?<0 Each field is a decialrepresentation of bits of the host I, followed by the chosen data port0 /or e1aple, a
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client with an I of @?0@0>0@, listenin) on port @F for the data connection will sendthe coand <!4T @?,@,>,@,@?,?<0 The port fields sho%ld be interpreted as p@V?F W
p? ; port, or, in this e1aple, @?V?F W ? ; @F0
In passive ode, the /T server opens a dynaic port (@F?"FFGF, sends the /T
client the servers I address to connect to and the port on which it is listenin) (a @ bit
val%e broen into a hi)h and low byte, lie e1plained before over the control strea andwaits for a connection fro the /T client0 In this case the /T client binds the so%rce portof the connection to a dynaic port between @F? and FFGF0
To %se passive ode, the client sends the PA)2 coand to which the server wo%ld
reply with soethin) siilar to <?? Enterin) assive +ode (@?,>,>,@,@?,F?<0 The synta1
of the I address and port are the sae as for the ar)%ent to the !4T coand0
In e1tended passive ode, the /T server operates e1actly the sae as passive ode,
however it only transits the port n%ber (not broen into hi)h and low bytes and theclient is to ass%e that it connects to the sae I address that was ori)inally connected to0
E1tended passive ode was added by 4/C ?? in $epteber @0
#hile data is bein) transferred via the data strea, the control strea sits idle0 This can
ca%se probles with lar)e data transfers thro%)h firewalls which tie o%t sessions afterlen)thy periods of idleness0 #hile the file ay well be s%ccessf%lly transferred, the control
session can be disconnected by the firewall, ca%sin) an error to be )enerated0
The /T protocol s%pports res%in) of interr%pted downloads %sin) the 4E$T coand0
The client passes the n%ber of bytes it has already received as ar)%ent to the 4E$T
coand and restarts the transfer0 In soe coandline clients for e1aple, there is anoften'i)nored b%t val%able coand, <re)et< (eanin) <)et a)ain< that will ca%se an
interr%pted <)et< coand to be contin%ed, hopef%lly to copletion, after a
co%nications interr%ption0
4es%in) %ploads is not as easy0 Altho%)h the /T protocol s%pports the AE coand
to append data to a file on the server, the client does not now the e1act position at which atransfer )ot interr%pted0 It has to obtain the si-e of the file soe other way, for e1aple
over a directory listin) or %sin) the $IXE coand0
The ob3ectives of 0TP4are-
• To proote sharin) of files (cop%ter pro)ras and3or data0
• To enco%ra)e indirect or iplicit %se of reote cop%ters0
•To shield a %ser fro variations in file stora)e systes aon) different hosts0
• To transfer data reliably, and efficiently0
Data forat
#hile transferrin) data over the networ, several data representations can be %sed0 The
two ost coon transfer odes are
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• A$CII ode
• Binary ode In <Binary ode<, the sendin) achine sends each file byte for byte
and as s%ch the recipient stores the bytestrea as it receives it0 (The /T standardcalls this <I+A.E< or <I< ode
In <A$CII ode<, any for of data that is not plain te1t will be corr%pted0 #hen a fileis sent %sin) an A$CII'type transfer, the individ%al letters, n%bers, and characters are sent
%sin) their A$CII character codes0 The receivin) achine saves these in a te1t file in theappropriate forat (for e1aple, a Uni1 achine saves it in a Uni1 forat, a #indows
achine saves it in a #indows forat0 2ence if an A$CII transfer is %sed it can beass%ed plain te1t is sent, which is stored by the receivin) cop%ter in its own forat0
Translatin) between te1t forats i)ht entail s%bstit%tin) the end of line and end of filecharacters %sed on the so%rce platfor with those on the destination platfor, e0)0 a
#indows achine receivin) a file fro a Uni1 achine will replace the line feeds withcarria)e ret%rn'line feed pairs0 It i)ht also involve translatin) charactersL for e1aple,
when transferrin) fro an IB+ ainfrae to a syste %sin) A$CII, EBCDIC characters %sedon the ainfrae will be translated to their A$CII e5%ivalents, and when transferrin) fro
the syste %sin) A$CII to the ainfrae, A$CII characters will be translated to theirEBCDIC e5%ivalents0
By defa%lt, ost /T clients %se A$CII ode0 $oe clients try to deterine there5%ired transfer'ode by inspectin) the files nae or contents, or by deterinin) whether
the server is r%nnin) an operatin) syste with the sae te1t file forat0
The /T specifications also list the followin) transfer odes
• EBCDIC ode ' this transfers bytes, e1cept they are encoded in EBCDIC rather than
A$CII0 Th%s, for e1aple, the A$CII ode server
• 6ocal ode ' this is desi)ned for %se with systes that are word'oriented rather thanbyte'oriented0
0TP and eb brosers+ost recent web browsers and file ana)ers can connect to /T servers, altho%)h they
ay lac the s%pport for protocol e1tensions s%ch as /T$0 This allows anip%lation of reote files over /T thro%)h an interface siilar to that %sed for local files0 This is done via
an /T U46, which taes the for ftp(s338ftpserveraddress: (e0)0, ftp33ftp0)ip0or)30 Apassword can optionally be )iven in the U46, e0)0
ftp(s338login:8 passord :Y8ftpserveraddress:8 port :0 +ost web'browsers re5%irethe %se of passive ode /T, which not all /T servers are capable of handlin)0 $oe
browsers allow only the downloadin) of files, b%t offer no way to %pload files to the server0
#ist of 0TP commands
Coands %sed by the /T client software as opposed to the %ser are often describedas raw /T coands0
• AB!4 ' Abort an active file transfer0
• ACCT ' Acco%nt inforation0
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• A66! ' Allocate s%fficient dis space to receive a file0
• AE ' Append0
• CDU ' Chan)e to arent Directory0
• C6NT ' $end /T Client Nae to server0
• C#D ' Chan)e worin) directory0
• DE6E ' Delete file0
• E$* ' Enter e1tended passive ode
• E4T ' $pecifies an e1tended address and port to which the server sho%ld
connect0
• /EAT ' .et the feat%re list ipleented by the server0 .ET ' Use to download afile fro reote
• 2E6 ' 4et%rns %sa)e doc%entation on a coand if specified, else a )eneral
help doc%ent is ret%rned0
• 6I$T ' 4et%rns inforation of a file or directory if specified, else inforation of
the c%rrent worin) directory is ret%rned0
• 6$* ' Enter lon) passive ode0
• 64T ' $pecifies a lon) address and port to which the server sho%ld connect
• +DT+ ' 4et%rn the last'odified tie of a specified file0
• +.ET ' Use to download %ltiple files fro reote0
• +9D ' +ae directory (folder0
• +NT ' +o%nt /ile $tr%ct%re0
• +!DE ' $ets the transfer ode ($trea, Bloc, or Copressed0
• +UT ' Use to %pload %ltiple files to reote0
• N6$T ' 4et%rns a list of filenaes in a specified directory0
• N!! ' No operation (d%y pacetL %sed ostly on eepalives0
• !T$ ' $elect options for a feat%re0
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• A$$ ' A%thentication password0
• A$* ' Enter passive ode0
• !4T ' $pecifies an address and port to which the server sho%ld connect0
• UT ' Use to %pload a file to reote0
• #D ' rint worin) directory0 4et%rns the c%rrent directory of the host0
• PUIT ' Disconnect0
• 4EIN ' 4e initiali-es the connection0
• 4E$T ' 4estart transfer fro the specified point0
• 4ET4 ' 4etrieve (download a reote file0
• 4+D ' 4eove a directory0
• 4N/4 ' 4enae fro0
• 4NT! ' 4enae to0
• $ITE ' $ends site specific coands to reote server0
• $IXE ' 4et%rn the si-e of a file0
• $+NT ' +o%nt file str%ct%re0
• $TAT ' 4et%rns the c%rrent stat%s0
• $T!4 ' $tore (%pload a file0
• $T!U ' $tore file %ni5%ely0
• $T4U ' $et file transfer str%ct%re0
• $H$T ' 4et%rn syste type0
• THE ' $ets the transfer ode
• U+NT ' Uno%nt file str%ct%re0
• U$E4 ' A%thentication %sernae
. Di;u t1e ;on;ept o8 Peertopeer
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Peer,to,peer Architect"re
!ften referred to siply as peer'to'peer, or abbreviated ?, peer'to'peer
architect%re is a type of networ in which each worstation has e5%ivalent capabilities andresponsibilities0 This differs fro client3server architect%res where soe cop%ters are
dedicated to servin) the others0 eer'to'peer networs are )enerally sipler b%t they
%s%ally do not offer the sae perforance %nder heavy loads0 The ? networ itself relieson cop%tin) power at the ends of a connection rather than fro within the networ itself0
? is often istaenly %sed as a ter to describe one %ser linin) with another %ser to
transfer inforation and files thro%)h the %se of a coon ? client to download +Gs,videos, ia)es, )aes and other software0 This, however, is only one type of ?
networin)0 .enerally, ? networs are %sed for sharin) files, b%t a ? networ can also
ean .rid Cop%tin) or Instant essa)in)0
Types of ? Networs
eer'to'peer networs coe in three flavors0 The cate)ory classification is based on
the networ and application0
Collaborative Comp"ting-
Also referred to as distrib%ted cop%tin), it cobines the idle or %n%sed CUprocessin) power and3or free dis space of any cop%ters in the networ0 Collaborative
cop%tin) is ost pop%lar with science and biotech or)ani-ations where intense cop%terprocessin) is re5%ired0 E1aples of distrib%ted cop%tin) can be fo%nd at .4ID0!4. where
United Devices is hostin) virt%al screenin) for cancer research on the .rid + platfor0 This
pro7ect has evolved into the lar)est cop%tational cheistry pro7ect in history0 UnitedDevices has harnessed the power of ore than ?,>>>,>>> Cs aro%nd the world to )enerate
ore than @>> teraflops of power0 +ost distrib%ted cop%tin) networs are created by
%sers vol%nteerin) their %n%sed cop%tin) reso%rces to contrib%te to p%blic interestresearch pro7ects0
.nstant &essaging-
!ne very coon for of ? networin) is Instant +essa)in) (I+ where software
applications, s%ch as +$N +essen)er or A!6 Instant +essen)er, for e1aple, allow %sers tochat via te1t essa)es in real'tie0 #hile ost vendors offer a free version of their I+
software others have be)%n to foc%s on enterprise versions of I+ software as b%siness andcorporations have oved towards ipleentin) I+ as a standard co%nications tool for
b%siness0
Affinity Comm"nities-
Affinity co%nities is the )ro%p of ? networs that is based aro%nd file'sharin) andbecae widely nown and taled abo%t d%e to the p%blic le)al iss%es s%rro%ndin) the direct
file sharin) )ro%p, Napster0 Affinity Co%nities are based on %sers collaboratin) andsearchin) other %sers cop%ters for inforation and files0
Ho Peer,to,peer 0ile,sharing Clients Wor'-
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!nce yo% have downloaded and installed a ? client, if yo% are connected to theInternet yo% can la%nch the %tility and yo% are then lo))ed into a central inde1in) server0
This central server inde1es all %sers who are c%rrently online connected to the server0 Thisserver does not host any files for downloadin)0 The ? client will contain an area where
yo% can search for a specific file0 The %tility 5%eries the inde1 server to find other connected%sers with the file yo% are looin) for0 #hen a atch is fo%nd the central server will tell yo%
where to find the re5%ested file0 Ho% can then choose a res%lt fro the search 5%ery andyo%r %tility when then attept to establish a connection with the cop%ter hostin) the file
yo% have re5%ested0 If a s%ccessf%l connection is ade, yo% will be)in downloadin) the file0!nce the file download is coplete the connection will be broen0
A second odel of ? clients wors in the sae way b%t witho%t a central inde1in)
server0 In this scenario the ? software siply sees o%t other Internet %sers %sin) thesae pro)ra and infors the of yo%r presence online, b%ildin) a lar)e networ of
cop%ters as ore %sers install and %se the software0
P5P )ec"rity Concerns-
!ne a7or concern of %sin) ? architect%re in the worplace is, of co%rse, networsec%rity0 $ec%rity concerns ste fro the architect%re itself0 Today we find ost blocin)and ro%tin) handles by a specific server within networ, b%t the ? architect%re has no
sin)le fi1ed server responsible for ro%tin) and re5%ests0 The first step in sec%rin) yo%r ?networ is to adopt a strict %sa)e policy within the worplace0 In sec%rin) yo%r networ
a)ainst attacs and vir%ses there are two ain strate)ies where foc%s is on controllin) thenetwor access or the foc%s is p%t on controllin) the files0 A protocol'based approach is
where syste adinistrators %se a software or hardware sol%tion to watch for and blocintr%sive networ traffic bein) received thro%)h the ? clients0 A second ethod of
protection is a software sol%tion which wo%ld provide file s%rveillance to actively search forfiles based on their type, their nae, their si)nat%re or even their content0
P5P at Wor'-
? is not only pop%lar with hoe %sers b%t any sall b%siness have coe to rely
on this cost'effective sol%tion for sharin) files with co'worers and clients0 ? prootes theease of worin) to)ether when yo%re not physically located in the sae office0 In 7%st
seconds %pdated files and data can be shared with peers and confidential files can bebloced for sec%rity0 Additionally, copanies can also bloc access to Internet %sic and
video files to assist in aintainin) a wor'oriented ? networ0 Not only does this eep thecopany free and clear fro le)al iss%es re)ardin) %sic downloadin) and sharin) b%t it
also eeps the corporate bandwidth %sa)e down0
*. Brie8l e<plain t1e tpe o8 aut1enti;ation5
@0 asswords
asswords are the easiest and ost coon a%thentication process that are %sed, not
only on destop cop%ters b%t also at the networ level0 2owever certain r%les sho%ld befollowed when settin) a password for yo%r cop%ter or Networ0 Do not %se easily
predictable words for yo%r passwordsL they dont even re5%ire a hacer to access thesyste thro%)h yo%r acco%nt0 Use passwords that are %npredictable0 $et lon) passwords
and %se n%bers and special characters when settin) yo%r password0 4eeber yo%r
passwordsL dont write it down anywhere0 2acers %se vario%s tools to now yo%r
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passwords, b%t a lon) password with a n%ber of special characters, indeed )ives the alot of tro%ble0
?0 Di)ital Certificates
Usin) a certain al)orith, cop%ter adinistrator cobine yo%r personal details with
other %ser credentials to )enerate a p%blic ey0 This p%blic ey or di)ital certificate is%sed for the a%thentication p%rpose in the networ0
G0 $art Cards
$art Cards are aon) the very few hardware a%thentication processes in which a
siple card with an ebedded circ%itry is %sed for accessin) the networ0 Each valid cardfor a partic%lar networ, when inserted into the circ%itry it has been ade for, )ives an
o%tp%t which decides whether yo% will be allowed to enter into the networ or not0 Thepro)rain) lo)ic inserted into each card is different and it is one of the safest ethods
of a%thentication0
0 /in)erprint detection
Alost available in all laptops that are an%fact%red todayL fin)erprint detection isanother safe ethod of cop%ter sec%rity a%thentication0 Everyone nows that even the
iris pattern of two people ay even atch, b%t fin)erprints can never atch0
F0 /ace reco)nition systes
/ace reco)nition syste, ay a%se yo%, b%t of late any people worin) in the field of
sec%rity have 5%estioned its %ser friendly nat%re and the sec%rity it can provide0 A siple
diension calc%lation of the face is done by the cop%ter and the lo)ic %sed in doin) so,has been often fo%nd to be prone to errors0
0 Bioetrics
Bioetrics is often considered as a far ore sec%re way of a%thentication than passwords or
di)ital certificates0 It is even safer than sart cards, which ay be isplaced0 The physicaland behavioral traits of a person are taen into consideration in this type of a%thentication0
0 Captcha 9eys
This is the process of a%thentication that is %sed to verify whether a h%an or a cop%ter
bot has lo))ed into the syste0 Captcha eys are randoly )enerated alphabets andn%ericals presented in s%ch a for, that only a h%an can reco)ni-e0
The above listed ethods are 7%st a few of the widely %sed a%thentication ethods0 In fact,the eas%res that we tae for safe)%ardin) o%r cop%ter or networ are ore iportant
than the ethod itself0 +any of %s have a habit of nain) o%r networs after theprota)onist fro o%r favorite ovie0 This sho%ld be avoided and networs sho%ld have
sensible naes that cannot be easily deterined0 If yo% are a networ adinistrator inchar)e of a closed sec%re networ, then it is always desirable to set yo%r networ visibility
stat%s to the invisible ode0
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20. 'rite a 1ort note on e page eitor. #/ o>De; +020F
This is a pro)ra that yo% %se to create #eb pa)es0 It can be soethin) as siple as thete1t editor that cae with yo%r cop%ter or it can be soethin) that creates the pa)e ri)ht
in front of yo% as yo% point and clic away0
If yo% lie to desi)n yo%r pa)es %sin) 2T+6 then yo% will probably %s a te1t editor of soesort0 They coe with a wide variety of options incl%din) teplates, spell checers, colorcodin) and %ch ore0
E1aples
#eb A%thorin) 3 2T+6 Editors 3 M2T+6 Editors
• Arachnophilia, by 0 6%t%s
2T+6 editor, pro)rain) editor for #indows0 Incl%des search3replace feat%res, spell
checer, will tidy %p yo%r ar%p, has c%stoi-ation available, acros, has b%ilt'in /T
service, ore0 $%pports A$ and 2, too0 6oyal followin) of devoted %sers0 /ree0 /or#indows0R$oftware by 0 6%t%s0S
• BBEdit, by Bare Bones $oftware
Top'ranin) 2T+6 editor for +acs0 Altho%)h I havent personally %sed it, those %sin)2oe$ite (for Cs, below and BBEdit copare the as siilar0 $ynta1 colorin) and
f%nction navi)ation s%pport for 2T+6, Java$cript, erl, 2, 4%by, $P6, M2T+6, M+6, andHA+60 $ynta1 colorin), f%nction navi)ation, and ar%p s%pport for C$$0 6ocal preview
server for preview of code )enerated by 2, erl, incl%des, and siilar0 B%ilt'in s%pport forDreaweaver0 +ore0 Try their 6ite version, or download a free trial fro their #eb site0
rices >@'?>> aro%nd @?F f%llL G>'> %p)radeL ed%cational0 /or +ac0R$oftware by
Bare Bones $oftware0S
• CoffeeC%p 2T+6 Editor, by CoffeeC%p $oftware, Inc0
2T+6 editor with #H$I#H.0 Incl%des /T, dra)'and'drop capabilities, M2T+6 conversion
tool, s%pport for 2 and other pro)rain) lan)%a)es, b%ilt in C$$ editor, spell chec,b%ilt in siteappin) tool, CoffeeC%p Ia)e +apper, %ch ore0
• Dreaweaver, by Adobe (forerly by +acroedia
Another top'ranin) 2T+6 pro)ra0 Inte)rates with +acroedia 2oe$ite, Adobe
/irewors, and other software pro)ras0 /ree trial download0 E1cellent 2T+6 editor, M2T+6
editor, accessible to those not nowin) 2T+6, and )ainin) in pop%larity aon) #eb sitedevelopers, copanies, lar)e corporations, and individ%als for #eb site b%ildin),
aintenance and especially for ana)in) lar)e sites0 Dreaweaver also s%pports #GC
4ecoendations and does pretty well with its #H$I#H. feat%res ' far s%perior to/ronta)e0 rices >@'?>> aro%nd G f%llL @ %p)rade, ed%cational0 /or #indows and
+ac0
• E1pression #eb Desi)ner, by +icrosoft
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E1pression #eb Desi)ner replaces /ronta)e and is a new prod%ct by +icrosoft, part of the E1pression faily that incl%des E1pression #eb Desi)ner, E1pression .raphic Desi)ner,
and E1pression Interactive Desi)ner0 +%ch better C$$ s%pport, better s%pport for #ebstandards than its predecessor0
• /ronta)e, by +icrosoft
Editor Note +ay ?>> /ronta)e was replaced with E1pression #eb Desi)ner as of this
note, yo%ll still find s%pport inforation at +icrosofts site0
• .o6ive, by Adobe
A direct copetitor with Dreaweaver, and a powerf%l #eb a%thorin) tool with #H$I#H.capabilities0 Also allows easy convertin) of Adobe InDesi)nZ layo%ts into #eb pa)es0 +ditor note &ay 5667- /o#ive development ill contin"e as a standalone softare prod"ct
$anno"nced by Adobe 8ovember 5669%4 altho"gh Adobe is also enco"raging "sers to sitch
to Dreameaver: /or #indows and +ac0R$oftware by Adobe0S
• 2oe$ite, by +acroedia
Top'ranin) 2T+6 software for Cs, aon) the top favorites %sed by #eb sitedevelopers0 $%pports 2, inte)rates well with Dreaweaver, Cold /%sion and other
pro)ras0 Accessible for new %sers, too0 E1cellent 2T+6 editor0 /ree trial download0 +ditor note 0ebr"ary 5669- Adobe and &acromedia merged: Home)ite development has been
stagnant for some time4 even tho"gh devoted Home)ite fans contin"e to hope for "pdates:Watch their site for the latest: rices >@'?>> aro%nd f%llL ? %p)rade0 /or #indows0
• 2T+6'9it Tools (/orerly 2T+6'9it, by Chai
op%lar #eb developer tool for 2T+6 and ore0 Incl%des any pl%)ins, s%ch as C$$,
2T+6 Tidy, #GC 2T+6 and C$$ references, M2T+6, Java$cript, A$, Cold/%sion, erl, 2,$$I, $P6, and ore0 rices >@'?>> aro%nd F f%llL free %p)rade for re)istered 2T+6'9it
@0> %sers0 /or #indows0R$oftware by Chai0S
• NoteTab, by /ooes $oftware
Top'rated te1t and 2T+6 editor shareware0 Awards fro C+a)a-ine and others0 $iple to%se and helpf%l with 2T+6, C$$, 2, C.I scripts, ore0 $earch3replace, dra) and drop
files, convert te1t to 2T+6, strip ta)s, ore0 rices >@'?>> aro%nd ?0F roL @0F$tandardL /ree 6ite version0 /or #indows0R$oftware by /ooes $oftware0S
• Te1tad, by 2elios $oftware $ol%tions
owerf%l, )eneral p%rpose editor for plain te1t files0 $pell checer, edit %ltiple files,
%nliited %ndo3redo, sortin), powerf%l search3replace, booars, file ana)er,coparison %tility, ore0 Add %tilities, clip libraries, dictionaries, acros, synta1 definitions,
and ore for )reater f%nctionality0 Aro%nd U$ ?, free trial download0 rices >@'?>>aro%nd GG0>> f%llL free %p)rade to Te1tad F fro Te1tpad 0 /or #indows0R$oftware by
2elios $oftware $ol%tions0S
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• Top$tyle C$$, 2T+6, M2T+6 Editor, by News.ator Technolo)ies
Top'rated editor for Cs (F stars with XDNet, C+a)a-ine, CNet, ore0 Inte)rates
sealessly with +acroedia 2oe$ite, +acroedia Dreaweaver, C$E 2T+6 *alidator,NoteTab, and others0 The 6ite version is already incl%ded in 2oe$ite (and possibly other
pro)ras, too0 op%lar pro)ra with #eb site developers0 2i)hly recoended by
#ebsiteTips0co and %sed for this #eb site0 Download trial or p%rchase online0 rices >@'?>> aro%nd 0F f%llL free %p)rade within version GL ?0F %p)rade prior to version GL/ree 6ite *ersion0 /or #indows0
22. Di;u t1e >ulnerailit o8 internet te;1nolog 8or e;urit t1reat.#/ o>De; +022F
#ireless networin) presents any advanta)es rod%ctivity iproves beca%se of
increased accessibility to inforation reso%rces0 Networ confi)%ration and reconfi)%rationis easier, faster, and less e1pensive0 2owever, wireless technolo)y also creates new threats
and alters the e1istin) inforation sec%rity ris profile0 /or e1aple, beca%seco%nications taes place <thro%)h the air< %sin) radio fre5%encies, the ris of
interception is )reater than with wired networs0 If the essa)e is not encrypted, orencrypted with a wea al)orith, the attacer can read it, thereby coproisin)
confidentiality0 Altho%)h wireless networin) alters the riss associated with vario%s threatsto sec%rity, the overall sec%rity ob7ectives reain the sae as with wired networs
preservin) confidentiality, ens%rin) inte)rity, and aintainin) availability of the inforationand inforation systes0 The ob7ective of this paper is to assist ana)ers in ain) s%ch
decisions by providin) the with a basic %nderstandin) of the nat%re of the vario%s threatsassociated with wireless networin) and available co%ntereas%res0
The pop%larity of wireless Networs is a testaent priarily to their convenience,
cost efficiency, and ease of inte)ration with other networs and networ coponents0 The
a7ority of cop%ters sold to cons%ers today coe pre'e5%ipped with all necessarywireless0
Networs technolo)y0 The benefits of wireless Networs incl%de Convenience,+obility, rod%ctivity, Deployent, E1pandability and Cost0
#ireless Networ technolo)y, while replete with the conveniences and advanta)esdescribed above has its share of downfalls0 /or a )iven networin) sit%ation, wireless
Networs ay not be desirable for a n%ber of reasons0 +ost of these have to do with theinherent liitations of the technolo)y0 The disadvanta)es of %sin) a wireless networ are
$ec%rity, 4an)e, 4eliability, and $peed0
#ireless Networs present a host of iss%es for networ ana)ers0 Una%thori-ed
access points, broadcasted $$IDs, %nnown stations, and spoofed +AC addresses are 7%st afew of
the probles addressed in #6AN tro%bleshootin)0 +ost networ analysis vendors, s%ch asNetwor Instr%ents, Networ .eneral, and /l%e, offer #6AN tro%bleshootin) tools or
f%nctionalities as part of their prod%ct line0
'irele Vulnerailitie, T1reat an Countermeaure
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The wireless networs consist of fo%r basic coponents The transission of data%sin) radio fre5%enciesL Access points that provide a connection to the or)ani-ational
networ and3or the Client devices (laptops, DAs, etc0L and Users0 Each of thesecoponents provides an aven%e for attac that can res%lt in the coproise of one or ore
of the three f%ndaental sec%rity ob7ectives of confidentiality, inte)rity, and availability0
2+. De;rie t1e ue o8 8orm in e o;ument an t1e te;1nolog 1i;1 t1e
8orm 1anle at t1e er>er. #/ o>De; +022F
%ntrou;tion to 'e "orm Page
#eb /ors pa)es to create pro)raable #eb pa)es that serve as the %ser interface foryo%r #eb application0 A #eb /ors pa)e presents inforation to the %ser in any browser or
client device and ipleents application lo)ic %sin) server'side code0 #eb /ors pa)eo%tp%t ay contain alost any 2TT'capable lan)%a)e, incl%din) 2T+6, M+6, #+6, and
EC+A$cript (J$cript, Java$cript0
#eb /ors pa)es are
• Based on +icrosoft A$0NET technolo)y in which code that r%ns on the server
dynaically )enerates #eb pa)e o%tp%t to the browser or client device0 /or details
abo%t A$0NET0
• Copatible with any browser or obile device0 A #eb /ors pa)e a%toatically
renders the correct browser'copliant 2T+6 for feat%res s%ch as styles, layo%t, andso on0 Alternatively, yo% can desi)n yo%r #eb /ors pa)es to r%n on a specific
browser s%ch as +icrosoft Internet E1plorer F and tae advanta)e of the feat%res of arich browser client0
• Copatible with any lan)%a)e s%pported by the 0NET coon lan)%a)e r%ntie,
incl%din) +icrosoft *is%al Basic, +icrosoft *is%al C=, and +icrosoft J$cript 0NET0
• B%ilt on the +icrosoft 0NET /raewor0 This provides all the benefits of the
fraewor, incl%din) a ana)ed environent, type safety, and inheritance0
• $%pported in *is%al $t%dio with powerf%l rapid application developent (4AD tools
for desi)nin) and pro)rain) yo%r fors0
Coponents of #eb /orsIn #eb /ors pa)es, the %ser interface pro)rain) is divided into two distinct
pieces the vis%al coponent and the lo)ic0 If yo% have wored with tools lie *is%al Basicand *is%al CWW in the past, yo% will reco)ni-e this division between the visible portion of a
for and the code behind the for that interacts with it0
The vis%al eleent is referred to as the #eb /ors page0 The pa)e consists of a file
containin) static 2T+6, or A$0NET server controls, or both si%ltaneo%sly0
The #eb /ors pa)e wors as a container for the static te1t and controls yo% want to
display0 Usin) the *is%al $t%dio #eb /ors Desi)ner pl%s A$0NET server controls, yo% candesi)n the for as yo% wo%ld in any *is%al $t%dio application0
Prepared ByMs. A.Subathra Devi, Asst. Prof. / MCA
7/23/2019 Web Programming Unit-II 2 & 16 Marks QA
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32
'e "orm "ile &tru;ture
The code'behind class files for all #eb /ors pa)es in a pro7ect are copiled into the
pro7ect dynaic'lin library (0dll file0 The 0asp1 pa)e file is also copiled, b%t soewhat
differently0 The first tie a %ser browses to the 0asp1 pa)e, A$0NET a%toatically)enerates a 0NET class file that represents the pa)e, and copiles it to a second 0dll file0The )enerated class for the 0asp1 pa)e inherits fro the code'behind class that was
copiled into the pro7ect 0dll file0 #hen a %ser re5%ests the #eb pa)e U46, the 0dll files r%non the server and dynaically prod%ce the 2T+6 o%tp%t for yo%r pa)e0 /or ore
inforation0
#hat #eb /ors a)es 2elp Ho% Accoplish#eb application pro)rain) presents challen)es that do not typically arise when
pro)rain) traditional client'based applications0 Aon) the challen)es are
• %mplementing a ri;1 'e uer inter8a;e. A %ser interface with a cople1 layo%t,
a lar)e ao%nt of dynaic content, and f%ll'feat%red %ser'interactive ob7ects can bediffic%lt and tedio%s to desi)n and ipleent %sin) basic 2T+6 facilities0 It is
partic%larly diffic%lt to create a rich %ser interface for applications liely to r%n onany different browser and client device platfors0
• &eparation o8 ;lient an er>er. In a #eb application, the client (browser and
server are different pro)ras often r%nnin) on different cop%ters (and even on
different operatin) systes0 Conse5%ently, the two halves of the application sharevery little inforationL they can co%nicate, b%t typically e1chan)e only sall
ch%ns of siple inforation0
• &tatele e<e;ution. #hen a #eb server receives a re5%est for a pa)e, it finds the
pa)e, processes it, sends it to the browser, and then, effectively, discards all pa)e
inforation0 If the %ser re5%ests the sae pa)e a)ain, the server repeats the entire
se5%ence, reprocessin) the pa)e fro scratch0 %t another way, a server has noeory of pa)es that it has processed0 Therefore, if an application needs to
aintain inforation abo%t a pa)e, this becoes a proble that has to be solved in
application code0
Prepared ByMs. A.Subathra Devi, Asst. Prof. / MCA
7/23/2019 Web Programming Unit-II 2 & 16 Marks QA
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33
• #n-non ;lient ;apailitie. In any cases, #eb applications are accessible to
any %sers %sin) different browsers0 Browsers have different capabilities, ain) it
diffic%lt to create an application that will r%n e5%ally well on all of the0
• Compli;ation it1 ata a;;e. 4eadin) fro and writin) to a data so%rce in a
traditional #eb applications can be coplicated and reso%rce'intensive0
• Compli;ation it1 ;alailit. In any cases #eb applications desi)ned with
e1istin) ethods fail to eet scalability )oals d%e to the lac of copatibilitybetween the vario%s coponents of the application0 This is often the sin)le fail%re
point for applications %nder a heavy )rowth cycle0
23. Create an online 1opping epage uing TM$ 8orm an ot1er te;1nologie
ne;ear 8or t1at. #/ o>De; +020F
hht!l
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Prepared ByMs. A.Subathra Devi, Asst. Prof. / MCA
7/23/2019 Web Programming Unit-II 2 & 16 Marks QA
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34
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33 4ef0 6ab ro)ra
AA #%VER&%TH
PART A
@0 2ow does a%dio and video effects to websiteK R4ef0 No0 F>S
?0 #hat is database driven website, how they b%iltK R4ef0 No0 F@S
G0 #hat is a phishin) web siteK R4ef0 No0 F?S
0 #hat is the typical database technolo)ies %sed for r%nnin) a database driven websiteK
R4ef0 No0 FFS
PART B
@0 #hat is /T, and how do I %se it to transfer filesK R4ef0 No0 S
?0 #rite a short note on web pa)e editors0 R4ef0 No0 @>S
Prepared ByMs. A.Subathra Devi, Asst. Prof. / MCA
7/23/2019 Web Programming Unit-II 2 & 16 Marks QA
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35
G0 Disc%ss the v%lnerability of internet technolo)y for sec%rity threats0 R4ef0 No0 @@S
0 Describe the %se of fors in web doc%ents and the technolo)y by which the fors
handled at the server0 R4ef0 No0 @?S
F0 Create an online shoppin) webpa)e %sin) 2T+6 fors and other technolo)ies necessary
for that0 R4ef0 No0 @GS