HTTP (syper text transfer protocol)(6).ppt

http full details work with ssh and wihtout sshl

1. HTTP
Hypertext Transfer Protocol

2. HTTP 2
What It Is
Protocolfortransferofvariousdata
formatsbetweenserverandclient
–Plaintext
–Hypertext
–Images
–Video
–Sound
Meta-informationalsotransferred

3. HTTP 3
Uniform Resources
URL
–UniformResourceLocator
–Referstoanexistingprotocol
http:,wais:,ftp:,mailto:,gopher:,news:
–Pointstoadocumentonaspecificserver
URN
–UniformResourceName
–Globallyunique,persistentidentifier
Independentoflocation

4. HTTP 4
Uniform Resources
URI
–UniformResourceIdentifier
–CollectionofURL’sandURN’s

5. HTTP 5
URL
<scheme>://<host>:<port>
/<path>;<parameters>?<query>
#<fragment>
–scheme
Theprotocolyouareusing
–host
Hostnameoripnumber
–port
TCPportnumberthatprotocolserverisusing
–path
Pathandfilenamereferenceofobjectonserver

6. HTTP 6
URL
<scheme>://<host>:<port>
/<path>;<parameters>?<query>
#<fragment>
–parameters
Anyspecificparametersthatobjectneeds
–query
QuerystringforaCGIprogram
–fragment
Referencetoasubsetofanobject

7. HTTP 7
URL and HTTP
AllpartsofURL,exceptparameters,
usedwithhttp
Schemeandhostcanbeomittedwhen
referencedobjectisonsamemachine
asreferringdocument
Portcanbeomittedsolongas
referencedhostisrunningonportlisted
inyour/etc/servicesfile
–Usuallyport80

8. HTTP 8
URL and HTTP
Fullpathusedwhenreferringto
anotherserver
–Relativepathonsameserver
ReferencewithrelativepathisapartialURL
QuerypassesparameterstoCGI
Fragmentjumpstolabelswithinapage
–http://www.x.y/z#foo

9. HTTP 9
Web Documents
–html
–ASCIItext
–Preformatted
postscript
–Images
GIF
JPEG
–Video
MPEG
–VRML
–Java

10. HTTP 10
Communication
Servertellsclientwhattypeof
informationiscoming before
informationarrives
–Fileextensions
.html.htm
.txt
.ps
.au
.gif.tiff.jpeg
.mpeg
.vrml.wrl
.java

11. HTTP 11
Communication
Textandinlineimages
–Separateobjects
Clientbrowsermayoptionallysenda
listofformatsitcanaccept
Documentcanbeaprogram
–Webserverexecutesprogramandsends
resultstoclient
–Generictermforthisprogramisscript,
gateway,orgatewayscript

12. HTTP 12
Scripts
Translatesinputfromclient
Callsotherprograms
Translatesoutputfromprogramsand
returnsittoclient

13. HTTP 13
Gateways
Translatesfromoneprotocolorservice
toanother
–HTTP/databasequery
–Databasequeryresults/HTTP

14. HTTP 14
HTTP 1.0
BernersLee,Fielding,Nielsen-1995
Usedinhypermediasystemsdistributed
acrossnetworks
Definesrequest-responseconversation
–Requestingprogram(client)establishes
connectionwithreceivingprogram(server)
–Clientsendsrequesttoserver
HTTPspecifiessyntax

15. HTTP 15
HTTP 1.0
Definesrequest-responseconversation
–Serverreplieswithresponse
httpspecifiessyntax
Doesnothandlenetworkconnectivity
orhowinformationistransmitted
TCP/IPdoesthis

16. HTTP 16
HTTP 1.0
HTTPrequest
–Method
–URI
–Protocolversion
–Optionalotherinformation
–Method[RequestURI]HTTP/1.0<CRLF>

17. HTTP 17
HTTP 1.0
Method
–Get
Returnsobject
–Head
Returnsinformationaboutobject
–Post
Sendsinformationtobestoredonserveroras
inputtoscript

18. HTTP 18
HTTP 1.0
Method
–Put
Sendsnewcopyofexistingobjecttoserver
Usuallynotallowed
–Delete
Deletesobject
Usuallynotallowed

19. HTTP 19
HTTP 1.0
Otherinformation
–UserAgent
Kindofbrowser
–If-Modified-Since
Returnsobjectonlyifmorerecentthangiven
date
Otherwisereturnsstatuscode304

20. HTTP 20
HTTP 1.0
Otherinformation
–Accept
Mimetypeswhichbrowsercanaccept
–MultipurposeInternetMailExtension
text/plain
text/html
application/postscript
image/gif
image/jpeg
audio/basic
video/mpeg
x-world/x-vrml

21. HTTP 21
HTTP 1.0
Otherinformation
–Authorization
Userpassword
GET/X/Y/Z.HTML HTTP1.0
UserAgent:Prodigy-WB/1.3e
Accept:text/plain
Accept:text/html
Accept:application/postscript
Accept:image/gif
–Accept:*/*

22. HTTP 22
HTTP 1.0
HTTPresponse
–Statusline
HTTP-versionStatus-codeReason
Status-codes1xx-Informational
–Reservedforfutureuse

23. HTTP 23
HTTP 1.0
HTTPresponse
–Statusline
Status-codes2xx-Success
–Theactionwassuccessfullyreceived,understood,
andaccepted
200OK
201POSTcommandsuccessful
202Requestaccepted
203GETorHEADrequestfulfilled
204Nocontent

24. HTTP 24
HTTP 1.0
HTTPresponse
–Statusline
Status-codes3xx-Redirection
–Furtheractionmustbetakeninordertocomplete
request
300Resourcefoundatmultiplelocations
301Resourcemovedpermanently
302Resourcemovedtemporarily
304Resourcehasnotmodified(sincedate)

25. HTTP 25
HTTP 1.0
HTTPresponse
–Statusline
Status-codes4xx-Clienterror
–Therequestcontainsbadsyntaxorcannotbe
fulfilled
400Badrequestfromclient
401Unauthorizedrequest
402Paymentrequiredforrequest
403Resourceaccessforbidden
404Resourcenotfound
405Methodnotallowedforresource
406Resourcetypenotacceptable

26. HTTP 26
HTTP 1.0
HTTPresponse
–Statusline
Status-codes5xx-Servererror
–Theserverfailedtofulfillanapparentlyvalidrequest
500Internalservererror
501Methodnotimplemented
502Badgatewayorserveroverload
503Serviceunavailable/gatewaytimeout
504Secondarygateway/servertimeout

27. HTTP 27
HTTP 1.0
HTTPresponse
–Descriptionofinformation
Server Typeofserver
Date Dateandtime
Content-Length Numberofbytes
Content-Type Mimetype
Content-LanguageEnglish,forexample
Content-EncodingDatacompression
Last-Modified Datewhenlastmodified
Expires Datewhenfilebecomes
invalid

28. HTTP 28
HTTP 1.0
Problems
–HTTPisstateless
EachrequestrequiresseparateTCPconnection
Serverdoesn’trememberpreviousrequests

29. HTTP 29
Evolution of HTTP
HTTP/0.9-1990
–Requestmethod+URI+crlf
GET/pets/index.html
Justfilecontentssentback
–Noheaderinformation
Gopherinfluence
–Mediatypes
Singlecharacterindicatedoneoftentypes

30. HTTP 30
Evolution of HTTP
HTTP/1.0-1995
–Meta-informationbetweenclientand
server
Mediatypes
–MIMEtype/subtype
Statuscodes
Thisinformationinfluencedthedevelopmentof
websearchengines
–Caching
–Authorization

31. HTTP 31
Evolution of HTTP
HTTP/1.0-1995
–Problems
Scalability
–Highnumberofclientsvisitserverforshorttime
Flashcrowd
Bandwidth

32. HTTP 32
Evolution of HTTP
HTTP/1.1
–Byteranges
Requestofadocumentsubset
–Adobe'sPortableDocumentFormat
–Streamingmultimedia
Eliminates unnecessary client/server
communication
Aninterruptedtransferwhichisrestartedcan
bemoreefficient

33. HTTP 33
Evolution of HTTP
HTTP/1.1
–Contentnegotiationwithqualityfactors
Qualityfactors
–Realnumbersbetween0and1
Defaultis1
Accept-Language:fr,en-gb;q=0.8,en;q=0.7

34. HTTP 34
Evolution of HTTP
HTTP/1.1
–Chunkedencoding
Transmissionofstreamingmultimedia
–Oneframevariesinsizeandcompositionfromthe
next
Streamingvideo
–Entireimagetransmittedinfirstchunkand
differencestothepreviousimagearetransmittedin
thenextchunk

35. HTTP 35
Evolution of HTTP
HTTP/1.1
–Protocolswitching
Clientcanspecifyanotherprotocolmoresuited
todatabeingtransferred
–Messageintegritychecks
–Digestauthentication
InHTTP/1.0,usersentusernameandpassword
overthenetwork
InHTTP/1.1,theclientandtheservernever
sendtheactualusernameorpasswordoverthe
network

36. HTTP 36
Evolution of HTTP
HTTP/1.1
–Persistentconnections
InHTTP/1.0,ifasinglepageincludesinline
images,multipleframes,animation,andother
externalreferences,tobrowsethispagewould
requiremanyreconnections
In HTTP/1.1 there are multiple
request/responsetransactionsperconnection
Clientscanpipelinerequeststotheserverby
sendingmultiplerequestsatstartofsession

37. HTTP 37
Evolution of HTTP
HTTP/1.1
–Cachemanagementwithentitytags
WhenbodyofURIchanges,sodoesitsentity
tag
–Usefulformaintainingcaches,asupdatedURI
informationwouldhaveadifferententitytag
Cantellifsameresourceisbeingcachedfrom
multipleURI'sasitwouldhavesameentitytag
Strongentitytag
–Changeswhenanyportionofresourcechanges
Oneormorebyteschange
Weakentitytag
–Changesonlywhensemanticsofentity-body
changes

38. HTTP 38
Evolution of HTTP
HTTP/1.1
–Softwaremultihoming
NumberofavailableIPaddressesisaconcern
InHTTP/1.0,servercouldhavemultipleDNS
entriesandIPaddresses,eachcorresponding
todifferentdocumenttree
InHTTP/1.1,servercouldhavemultipleDNS
entriesandonlyasingleIPaddress

39. HTTP 39
The Future
HTTP-NextGeneration
–Manychannels
OneTCPconnectioncarriesmultiplechannels
forparallelcommunication
Differentprotocolsoneachchannel
–Traditionalway
MultipleTCPconnectionsbetweensameclient
andserver
Pagescontainimages,video,audio,andhtml

40. HTTP 40
The Future
Extensibility
–AddingnewMIMEheadershasbeenthe
traditionalwayofextendinghttp
–Drawbacks
Noindicationwhetherreceivingend
understandstheseextensions
Noindicationwhetherextensionisintendedfor
allpartiesalongmessagepathoronlyfor
certainintermediaries
Noindicationoforderinwhichextensions
shouldbeinterpreted

41. HTTP 41
The Future
Extensibility
–PEP
ProtocolExtensionProtocol

42. HTTP 42
The Future
Performance
–ParsingMIMEheaderswastesresources
–Stickyheaders
Persistentstatebetweenmultiplehttprequests
Notallheadershavetobeincludedinevery
httpmessage
Distributedauthoring
–Eventnotification

43. HTTP 43
The Future
Cachingandreplication
–Popularsitesarereallypopular
–Flashcrowdshappen
–Hotspotsonthenetaredynamic
–Amountofdynamicdataisincreasing

44. HTTP 44
The Future
QoS
–Qualityofservice
–Noteverythingmustbetreatedwithsame
QoS
–RequiredQoSshouldbemadeattheuser-
interface

45. HTTP 45
The Future
Real-timeprotocolsandtheweb
–Streamingprotocols
Audio/video-on-demand