HTTP(Hyper Text Transfer Protocol)�

The Hypertext Transfer Protocol (HTTP) is a protocol used mainly to access data on the World Wide Web.
HTTP functions as a combination of FTP and SMTP.
It is similar to FTP because it transfers files and uses the services of TCP.
It is much simpler than FTP because it uses only one TCP connection.
There is no separate control connection; only data are transferred between the client and the server.

1. HTTP(Hyper Text Transfer Protocol)
Dr R JegadeesanProf-CSE
JyothishmathiInstitute of Technology
and Science, Karimnagar

2. •TheHypertextTransferProtocol(HTTP)isa
protocolusedmainlytoaccessdataonthe
WorldWideWeb.
•HTTPfunctionsasacombinationofFTP
andSMTP.
•ItissimilartoFTPbecauseittransfersfiles
andusestheservicesofTCP.
•ItismuchsimplerthanFTPbecauseituses
onlyoneTCPconnection.
•Thereisnoseparatecontrolconnection;
onlydataaretransferredbetweentheclient
andtheserver.

3. •HTTPislikeSMTPbecausethedatatransferred
betweentheclientandtheserverlooklikeSMTP
messages.
•TheformatofthedataiscontrolledbyMIME-like
headers.
•UnlikeSMTP,theHTTPmessagesarenotdestinedto
bereadbyhumans;theyarereadandinterpretedbythe
HTTPserverandHTTPclient(browser)
•SMTPmessagesarestoredandforwarded,butHTTP
messagesaredeliveredimmediately

4. •Thecommandsfromtheclienttotheserverare
embeddedinarequestmessage.
•Thecontentsoftherequestedfileorother
informationareembeddedinaresponse
message.
•ASSMTPusestheservicesofTCPonwell-
knownport25,POP3uses110,IMAP4uses143
portnumber
•HTTPusestheservicesofTCPonwell-known
port80.

5. HTTP Transaction
•FigureillustratestheHTTPtransaction
betweentheclientandserver.
•Theclientinitializesthetransactionby
sendingarequestmessage.
•Theserverrepliesbysendingaresponse
message

7. Messages
•Theformatsoftherequestandresponse
messagesaresimilar;bothareshownin
figure
•Arequestmessageconsistsofarequestline,
aheader,andsometimesabody.
•Aresponsemessageconsistsofastatusline,a
header,andsometimesabody.

9. Request and Status Line
•Thefirstlineinarequestmessageiscalleda
requestline;
•Thefirstlineintheresponsemessageis
calledthestatusline.
•Thereisonecommonfield,asshownin
Figure

11. Request type.
•Thisfieldisusedintherequestmessage.
•Inversion1.1ofHTTP,severalrequesttypesaredefined.
theyare
➢GET
➢HEAD
➢POST
➢PUT
➢CONNECT

12. •GET
Requests a document from the server
•HEAD
Requests information about a document but
not the document itself.
•POST
Client submits data to be processed to a
specified server

13. •PUT
Sends a document from the server to client
•CONNECT
Reserved(connection established between
client and server)

14. •Status code
➢Thestatuscodefieldissimilartothoseinthe
FTPandtheSMTPprotocols.
➢Itconsistsofthreedigitscode.
➢Whereasthecodesinthe100rangeareonly
informational
➢thecodesinthe200rangeindicateasuccessful
request.
➢Thecodesinthe300rangeredirecttheclientto
anotherURL
➢thecodesinthe400rangeindicateanerrorat
theclientsite.
➢Finally,thecodesinthe500rangeindicatean
errorattheserversite.

17. Statusphrase.
•Thisfieldisusedintheresponsemessage.It
explainsthestatuscodeintextform
HTTP Version.
The most current version of HTTP is 1.1.

18. Header
•Theheaderexchangesadditionalinformation
betweentheclientandtheserver.
•Theheadercanconsistofoneormoreheader
lines.
•Eachheaderlinehasaheadername,acolon,
aspace,andaheadervalue

19. •A header line belongs to one of four categories:
•General Header
•Request Header
•Response Header
•Entity Header
•A request message can contain only general,
request, and entity headers.
•A response messagecan contain only general,
response, and entity headers

20. General header
➢Thegeneralheadergivesgeneralinformation
aboutthemessageandcanbepresentinbotha
requestandaresponse.
➢Cache-controlSpecifiesinformationabout
caching
➢ConnectionShowswhethertheconnection
shouldbeclosedornotbetweenclientandserver
➢DateShowsthecurrentdate
➢MIME-versionShowstheMIMEversionused

21. Request Header
•Therequestheadercanbepresentonlyina
requestmessage.
•Itspecifiestheclient'sconfigurationandthe
client'spreferreddocumentformat
•Listofsomerequestheadersandtheir
descriptions.

22. •Accept
Shows the format the client can accept
•Accept-charset
Shows the character set the client can handle
•Accept-encoding
Shows the encoding scheme the client can
handle
•Accept-language
Shows the language the client can accept
•From
Shows the e-mail address of the user
•Host
Shows the host and port number of the server

23. •If-modified-since
Sends the document if newer than specified
date
•If-match
Sends the document only if it matches given
request
•If-range
Sends only the portion of the document
•Referrer
Specifies the URL of the linked document
•User-agent
Identifies the client program

24. Response header
•Theresponseheadercanbepresentonlyina
responsemessage.
•Itspecifiestheserver'sconfigurationand
specialinformationabouttherequest
•Listofsomeresponseheaderswiththeir
descriptions

25. •Accept-range
Showsifserveracceptstherangeof
documentrequestedbyclient
•Public
Shows the supported list of methods
•Retry-after
Specifies the date after which the server is
available
•Server
Shows the server name and version number

26. Entity header
•The entity header gives information about the body
of the document.
•Given below List of some entity headers and their
descriptions.
➢Content-encodingSpecifies the encoding scheme
➢Content-languageSpecifies the language
➢Content-lengthShows the length of the document
➢Content-rangeSpecifies the range of the document
➢Content-typeSpecifies the data type

27. Body
•Thebodycanbepresentinarequestor
responsemessage.
•Usually,itcontainsthedocumenttobesent
orreceived.

28. Network security

29. •Networksecurityisprotectionofthe
accesstofilesanddirectoriesin
computernetworkagainsthacking,
misuseandunauthorizedchangesto
thefile.

30. SECURITY SERVICES
•Network security can provide one of the five
services.
➢Message Confidentiality,
➢Message Integrity
➢Authentication
➢Non repudiation
➢Entity Authentication Or Identification

31. Message Confidentiality
•Message confidentiality or privacy means that the
sender and the receiver expect confidentiality.
•The transmitted message must make sense to
only the intended receiver.
•To all others, the message must be garbage.
•ForexampleWhenacustomercommunicates
withherbank,sheexpectsthatthe
communicationistotallyconfidential.

32. Message Integrity
•Messageintegritymeansthatthedatamust
arriveatthereceiverexactlyastheyweresent.
•Theremustbenochangesduringthe
transmission,neitheraccidentallynor
maliciously.
•Asmoreandmoremoneyexchangesoccurover
theInternet,integrityiscrucial.
•Forexample,itwouldbedisastrousifarequest
fortransferringRs1000changedtoarequestfor
Rs10,000orRs1,00,000.

33. Authentication
•Itreferstotheprocessofverifyingthe
identityofanentityinvolvedinthe
communicationprocessi.e.determiningthe
identityofanentitybeforerevealingthe
sensitiveinformation.
•Theprocessofidentifyinganindividual,
usuallybasedonausernameandpassword.

34. Non repudiation
•Messagenonrepudiationmeansthatasender
mustnotbeabletodenysendingamessagethat
heorshe,infact,didsend.
•Nonrepudiationisawaytoguaranteethatthe
senderofamessagecannotlaterdenyhaving
sentthemessageandthattherecipientcannot
laterdenyhavingreceivedthemessage.
•Nonrepudiationcanbeobtainedthroughthe
useofdigitalsignatures.

35. Entity authentication
•Entity authenticationis a technique designed
to let one party prove the identity of another
party.
•Anentitycan be a person, a process, a client,
or a server.
•Theentitywhose identity needs to be proved
is called the claimant
•The entity that tries to prove the identity of
the claimantis called the verifier.

36. Thank you