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HTTP Network Basic2016.11.30()

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I N D E X

01HTTP

01HTTP HTTP(HyperText Tranfer Protocol) .HTTP Request , Response ., Request Response .

ClientServerURL , .( .)HTTP (Client )PC runningFirefox browserserver runningApache WebserveriPhone runningSafari browser

HTTP request

HTTP response

HTTP request

HTTP response

client: browser that requests, receives, (using HTTP protocol) and displays Web objects server: Web server sends (using HTTP protocol) objects in response to requests

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01HTTP HTTP(HyperText Tranfer Protocol) Request Message HTTP Request .request line(GET, POST, HEAD commands)

header lines

carriage return, line feed at startof line indicatesend of header linesGET /index.html HTTP/1.1\r\nHost: www-net.cs.umass.edu\r\nUser-Agent: Firefox/3.6.10\r\nAccept: text/html,application/xhtml+xml\r\nAccept-Language: en-us,en;q=0.5\r\nAccept-Encoding: gzip,deflate\r\nAccept-Charset: ISO-8859-1,utf-8;q=0.7\r\nKeep-Alive: 115\r\nConnection: keep-alive\r\n\r\n

carriage return characterline-feed character

MethodURI

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HTTP request message: general formatrequestlineheaderlines

body

methodspspcrlfversionURL

crlfvalueheader field name

crlfvalueheader field name

~~

~~

crlf

entity body

~~

~~cr lf = carriage return line feed

01HTTP HTTP(HyperText Tranfer Protocol) Response Message Request Response .status line(protocolstatus codestatus phrase)

header lines

data, e.g., requestedHTML fileHTTP/1.1 200 OK\r\nDate: Sun, 26 Sep 2010 20:09:20 GMT\r\nServer: Apache/2.0.52 (CentOS)\r\nLast-Modified: Tue, 30 Oct 2007 17:00:02 GMT\r\nETag: "17dc6-a5c-bf716880"\r\nAccept-Ranges: bytes\r\nContent-Length: 2652\r\nKeep-Alive: timeout=10, max=100\r\nConnection: Keep-Alive\r\nContent-Type: text/html; charset=ISO-8859-1\r\n\r\ndata data data data data ...

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01HTTP HTTP(HyperText Tranfer Protocol) stateless ( )HTTP stateless . HTTP , Request Response . , HTTP Request Response .

HTTP Request Response . , cookie session .HTTP(HyperText Tranfer Protocol) Request URI HTTP URI(Uniform Resource Identifiers) .

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01HTTP HTTP(HyperText Tranfer Protocol) Method -> .

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01HTTP HTTP(HyperText Tranfer Protocol) Method -> .Request , Method . . , .HTTP 1.0 1.1 .Method typesHTTP/1.0:GETPOSTPUTDELETEHEADasks server to leave requested object out of response

HTTP/1.1:GET, POST, HEAD, TRACE, CONNECTPUTuploads file in entity body to path specified in URL fieldDELETEdeletes file specified in the URL field

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01HTTP TCP (Non-persistent)HTTP , Text , HTTP .Non-persistent HTTP: response time

time to transmit file

initiate TCPconnection

RTT

requestfile

RTT

filereceivedtimetime

HTTP:1. HTTP HTTP 80 www.someschool.edu TCP . TCP .

2. HTTP 1 TCP HTTP . /somedepartment/home.index .

3. HTTP 1 . /somedepartment/home.index , HTTP .

4. HTTP TCP TCP .( TCP )

5. HTTP ,TCP . HTML . HTML 10 JPEG .

6. JPEG 4 .RTT : Round Trip Time. = .

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01HTTP TCP (Persistent)TCP . TCP .( HTTP () , .)TCP , .persistent HTTP:server leaves connection open after sending responsesubsequent HTTP messages between same client/server sent over open connectionclient sends requests as soon as it encounters a referenced objectas little as one RTT for all the referenced objects

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Thanks. Have a good day.

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