powerpoint http

8/20/2019 Powerpoint Http

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HTTPHTTP

Hypertext TransferHypertext Transfer

ProtocolProtocol


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HTTP 2

What It IsWhat It Is

Protocol for transfer of various dataProtocol for transfer of various data

formats between server and clientformats between server and client

– PlaintextPlaintext– HypertextHypertext

– ImagesImages

– VideoVideo– SoundSound

Metainformation also transferredMetainformation also transferred


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HTTP 3

!niform "esources!niform "esources

!"#!"#– !niform "esource #ocator!niform "esource #ocator

– "efers to an existing protocol"efers to an existing protocol http$% wais$% ftp$% mailto$% gopher$% news$http$% wais$% ftp$% mailto$% gopher$% news$

– Points to a document on a speci&c serverPoints to a document on a speci&c server

!"'!"'

– !niform "esource 'ame!niform "esource 'ame

– (lobally uni)ue% persistent identi&er(lobally uni)ue% persistent identi&er Independent of locationIndependent of location


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HTTP 4

!niform "esources!niform "esources

!"I!"I– !niform "esource Identi&er!niform "esource Identi&er

– *ollection of !"#+s and !"'+s*ollection of !"#+s and !"'+s


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HTTP 5

!"#!"#

: // : : // : / ; ? / ; ?##– schemescheme

,he protocol you are using ,he protocol you are using

– hosthost Host name or ip numberHost name or ip number

– portport ,*P port number that protocol server is using ,*P port number that protocol server is using

– pathpath Path and &lename reference of ob-ect on serverPath and &lename reference of ob-ect on server


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HTTP 6

!"#!"#

: // : : // :

/ ; ? / ; ?

##– parametersparameters

.ny speci&c parameters that ob-ect needs.ny speci&c parameters that ob-ect needs

– )uery)uery /uery string for a *(I program/uery string for a *(I program

– fragmentfragment "eference to a subset of an ob-ect"eference to a subset of an ob-ect


7/45HTTP 7

!"# and H,,P!"# and H,,P

.ll parts of !"#% except parameters%.ll parts of !"#% except parameters%

used with httpused with http

Scheme and host can be omitted whenScheme and host can be omitted whenreferenced ob-ect is on same machinereferenced ob-ect is on same machine

as referring documentas referring document

Port can be omitted so long asPort can be omitted so long asreferenced host is running on portreferenced host is running on port

listed in your 0etc0services &lelisted in your 0etc0services &le– !sually port 12!sually port 12


8/45HTTP 8

!"# and H,,P!"# and H,,P

3ull path used when referring to3ull path used when referring to

another serveranother server

– "elative path on same server"elative path on same server "eference with relative path is a"eference with relative path is a partialpartial

URLURL

/uery passes parameters to *(I/uery passes parameters to *(I 3ragment -umps to labels within a3ragment -umps to labels within a

pagepage– http$00www4x4y056foohttp$00www4x4y056foo


9/45HTTP 9

Web 7ocumentsWeb 7ocuments

– htmlhtml– .S*II text.S*II text–

PreformattedPreformatted postscriptpostscript

– ImagesImages (I3(I3 8P9( 8P9(

– VideoVideo MP9(MP9(

– V"M#V"M#– 8ava 8ava


10/45HTTP 10

*ommunication*ommunication

Server tells client what type ofServer tells client what type ofinformation is coming before informationinformation is coming before informationarrivesarrives– 3ile extensions3ile extensions

4html 4htm4html 4htm 4txt4txt 4ps4ps 4au4au 4gif 4ti: 4-peg4gif 4ti: 4-peg 4mpeg4mpeg 4vrml 4wrl4vrml 4wrl 4-ava4-ava


11/45HTTP 11

*ommunication*ommunication

,ext and inline images ,ext and inline images

– Separate ob-ectsSeparate ob-ects

*lient browser may optionally send a*lient browser may optionally send alist of formats it can acceptlist of formats it can accept

7ocument can be a program7ocument can be a program

–Web server executes program and sendsWeb server executes program and sendsresults to clientresults to client

– (eneric term for this program is(eneric term for this program is script script %%

gateway gateway % or% or gateway script gateway script


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13/45HTTP 13

(ateways(ateways

,ranslates from one protocol or ,ranslates from one protocol orservice to anotherservice to another

– H,,P 0 database )ueryH,,P 0 database )uery– 7atabase )uery results 0 H,,P7atabase )uery results 0 H,,P


14/45HTTP 14

H,,P ;42H,,P ;42

!sed in hypermedia systems!sed in hypermedia systems

distributed across networ?sdistributed across networ?s 7e&nes re)uestresponse conversation7e&nes re)uestresponse conversation

– "e)uesting program @clientA establishes"e)uesting program @clientA establishesconnection with receiving program @serverAconnection with receiving program @serverA

– *lient sends re)uest to server*lient sends re)uest to server H,,P speci&es syntaxH,,P speci&es syntax


15/45HTTP 15

H,,P ;42H,,P ;42

7e&nes re)uestresponse7e&nes re)uestresponse

conversationconversation

– Server replies with responseServer replies with response http speci&es syntaxhttp speci&es syntax

7oes not handle networ?7oes not handle networ?

connectivity or how information isconnectivity or how information istransmittedtransmitted

,*P0IP does this ,*P0IP does this


16/45HTTP 16

H,,P ;42H,,P ;42

H,,P re)uestH,,P re)uest

– MethodMethod

– !"I!"I

– Protocol versionProtocol version

– Bptional other informationBptional other information

– Method [Request UR! "$/%&'Method [Request UR! "$/%&'


17/45HTTP 17

H,,P ;42H,,P ;42

MethodMethod

– (et(et "eturns ob-ect"eturns ob-ect

– HeadHead "eturns information about ob-ect"eturns information about ob-ect

– PostPost Sends information to be stored on serverSends information to be stored on server

or as input to scriptor as input to script


18/45HTTP 18

H,,P ;42H,,P ;42

MethodMethod

– PutPut Sends new copy of existing ob-ect toSends new copy of existing ob-ect to

serverserver

!sually not allowed!sually not allowed

– 7elete7elete 7eletes ob-ect7eletes ob-ect

!sually not allowed!sually not allowed


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HTTP 21

H,,P ;42H,,P ;42

Bther informationBther information

– .uthori5ation.uthori5ation

!ser password!ser password(9, 0F0G04H,M# H,,P ;42(9, 0F0G04H,M# H,,P ;42

!ser .gent$ ProdigyW


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HTTP 22

H,,P ;42H,,P ;42

H,,P responseH,,P response

– Status lineStatus line H,,Pversion Statuscode "easonH,,Pversion Statuscode "eason Statuscodes ;xx InformationalStatuscodes ;xx Informational

– "eserved for future use"eserved for future use


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HTTP 23

H,,P ;42H,,P ;42


– Status lineStatus line Statuscodes Jxx SuccessStatuscodes Jxx Success

– ,he action was successfully received% ,he action was successfully received%

understood% and acceptedunderstood% and accepted J22 BC J22 BC J2;J2; PBS, command successfulPBS, command successful J2JJ2J "e)uest accepted"e)uest accepted J2DJ2D (9, or H9.7 re)uest ful&lled(9, or H9.7 re)uest ful&lled J2EJ2E 'o content'o content


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HTTP 25

H,,P ;42H,,P ;42


– Status lineStatus line

Statuscodes Exx *lient errorStatuscodes Exx *lient error– ,he re)uest contains bad syntax or cannot be ful&lled ,he re)uest contains bad syntax or cannot be ful&lled

E22E22 Method not allowed for resourceMethod not allowed for resource

E2KE2K "esource type not acceptable"esource type not acceptable


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HTTP 26

H,,P ;42H,,P ;42


– Status lineStatus line

Statuscodes >xx Server errorStatuscodes >xx Server error– ,he server failed to ful&ll an apparently valid ,he server failed to ful&ll an apparently valid

re)uestre)uest >22>22 Internal server errorInternal server error

>2;>2; Method not implementedMethod not implemented >2J>2J 2D Service unavailable 0 gateway timeoutService unavailable 0 gateway timeout >2E>2E Secondary gateway 0 server timeoutSecondary gateway 0 server timeout


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HTTP 27

H,,P ;42H,,P ;42

H,,P responseH,,P response– 7escription of information7escription of information

ServerServer ,ype of server ,ype of server 7ate7ate 7ate and time 7ate and time *ontent#ength*ontent#ength 'umber of bytes 'umber of bytes *ontent,ype*ontent,ype Mime type Mime type *ontent#anguage*ontent#anguage 9nglish% for example 9nglish% for example

*ontent9ncoding*ontent9ncoding 7ata compression 7ata compression #astModi&ed#astModi&ed 7ate when last modi&ed 7ate when last modi&ed 9xpires9xpires 7ate when &le becomes7ate when &le becomes

invalidinvalid


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HTTP 28

H,,P ;42H,,P ;42

ProblemsProblems

– H,,P is statelessH,,P is stateless 9ach re)uest re)uires separate ,*P9ach re)uest re)uires separate ,*P

connectionconnection

Server doesn+t remember previousServer doesn+t remember previous

re)uestsre)uests


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30/45

HTTP 30

9volution of H,,P9volution of H,,P

H,,P0;42 ;==>H,,P0;42 ;==>

– Metainformation between client and serverMetainformation between client and server

Media typesMedia types– MIM9 type0subtypeMIM9 type0subtype

Status codesStatus codes

,his information inuenced the development of ,his information inuenced the development of

web search enginesweb search engines

– *aching*aching

– .uthori5ation.uthori5ation


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HTTP 31


H,,P0;42 ;==>H,,P0;42 ;==>

– ProblemsProblems

ScalabilityScalability– High number of clients visit server for shortHigh number of clients visit server for short

timetime

3lash crowd3lash crowd


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HTTP 33


H,,P0;4;H,,P0;4;

– *ontent negotiation with )uality*ontent negotiation with )uality

factorsfactors /uality factors/uality factors

– "eal numbers between 2 and ;"eal numbers between 2 and ;

7efault is ;7efault is ;

.ccept#anguage$ fr% engb )Q241% en.ccept#anguage$ fr% engb )Q241% en)Q24R)Q24R


34/45

HTTP 34


H,,P0;4;H,,P0;4;

– *hun?ed encoding*hun?ed encoding

,ransmission of streaming multimedia ,ransmission of streaming multimedia– Bne frame varies in si5e and composition fromBne frame varies in si5e and composition from

the nextthe next

Streaming videoStreaming video

– 9ntire image transmitted in &rst chun? and9ntire image transmitted in &rst chun? anddi:erences to the previous image aredi:erences to the previous image are

transmitted in the next chun?transmitted in the next chun?


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HTTP 35


H,,P0;4;H,,P0;4;– Protocol switchingProtocol switching

*lient can specify another protocol more suited*lient can specify another protocol more suitedto data being transferredto data being transferred

– Message integrity chec?sMessage integrity chec?s

– 7igest authentication7igest authentication In H,,P0;42% user sent username and passwordIn H,,P0;42% user sent username and password

over the networ?over the networ? In H,,P0;4;% the client and the server neverIn H,,P0;4;% the client and the server never

send the actual username or password oversend the actual username or password overthe networ?the networ?


36/45

HTTP 36


H,,P0;4;H,,P0;4;

– Persistent connectionsPersistent connections

In H,,P0;42% if a single page includes inlineIn H,,P0;42% if a single page includes inlineimages% multiple frames% animation% and otherimages% multiple frames% animation% and other

external references% to browse this pageexternal references% to browse this page

would re)uire many reconnectionswould re)uire many reconnections

In H,,P0;4; there are multipleIn H,,P0;4; there are multiple

re)uest0response transactions per connectionre)uest0response transactions per connection *lients can pipeline re)uests to the server by*lients can pipeline re)uests to the server by

sending multiple re)uests at start of sessionsending multiple re)uests at start of session


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HTTP 37


H,,P0;4;H,,P0;4;– *ache management with entity tags*ache management with entity tags

When body of !"I changes% so does its entity tagWhen body of !"I changes% so does its entity tag

– !seful for maintaining caches% as updated !"I!seful for maintaining caches% as updated !"Iinformation would have a di:erent entity taginformation would have a di:erent entity tag

*an tell if same resource is being cached from*an tell if same resource is being cached frommultiple !"INs as it would have same entity tagmultiple !"INs as it would have same entity tag

Strong entity tagStrong entity tag– *hanges when any portion of resource changes*hanges when any portion of resource changes

Bne or more bytes changeBne or more bytes change Wea? entity tagWea? entity tag

– *hanges only when semantics of entitybody changes*hanges only when semantics of entitybody changes


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HTTP 38


H,,P0;4;H,,P0;4;

– Software multihomingSoftware multihoming

'umber of available IP addresses is a'umber of available IP addresses is aconcernconcern

In H,,P0;42% server could have multipleIn H,,P0;42% server could have multiple

7'S entries and IP addresses% each7'S entries and IP addresses% each

corresponding to di:erent document treecorresponding to di:erent document tree In H,,P0;4;% server could have multipleIn H,,P0;4;% server could have multiple

7'S entries and only a single IP address7'S entries and only a single IP address


39/45

HTTP 39

,he 3uture ,he 3uture

H,,P'ext (enerationH,,P'ext (eneration

– Many channelsMany channels

Bne ,*P connection carries multipleBne ,*P connection carries multiplechannels for parallel communicationchannels for parallel communication

7i:erent protocols on each channel7i:erent protocols on each channel

– ,raditional way ,raditional way

Multiple ,*P connections between sameMultiple ,*P connections between sameclient and serverclient and server

Pages contain images% video% audio% and htmlPages contain images% video% audio% and html


40/45

HTTP 40


9xtensibility9xtensibility– .dding new MIM9 headers has been the.dding new MIM9 headers has been the

traditional way of extending httptraditional way of extending http

– 7rawbac?s7rawbac?s 'o indication whether receiving end'o indication whether receiving end

understands these extensionsunderstands these extensions 'o indication whether extension is intended'o indication whether extension is intended

for all parties along message path or only forfor all parties along message path or only forcertain intermediariescertain intermediaries

'o indication of order in which extensions'o indication of order in which extensionsshould be interpretedshould be interpreted


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HTTP 42


PerformancePerformance

– Parsing MIM9 headers wastes resourcesParsing MIM9 headers wastes resources

– Stic?y headersStic?y headers Persistent state between multiple httpPersistent state between multiple http

re)uestsre)uests

'ot all headers have to be included in every'ot all headers have to be included in every

http messagehttp message 7istributed authoring7istributed authoring

– 9vent noti&cation9vent noti&cation


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HTTP 43


*aching and replication*aching and replication

– Popular sites arePopular sites are rea++yrea++y popularpopular

– 3lash crowds happen3lash crowds happen– Hot spots on the net are dynamicHot spots on the net are dynamic

– .mount of dynamic data is increasing.mount of dynamic data is increasing


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HTTP 44


/oS/oS

– /uality of service/uality of service

– 'ot everything must be treated with'ot everything must be treated withsame /oSsame /oS

– "e)uired /oS should be made at the"e)uired /oS should be made at the

userinterfaceuserinterface


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"ealtime protocols and the web"ealtime protocols and the web

– Streaming protocolsStreaming protocols

.udio0videoondemand.udio0videoondemand

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