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Web and HTTP Protocols: A Comprehensive Overview, Study notes of Engineering

University of Calgary Engineering

A comprehensive overview of web and http protocols, covering key concepts such as http request and response messages, persistent and non-persistent connections, web caching, and the role of dns. It also delves into the workings of smtp, explaining its three phases and how it differs from http. Well-structured and uses clear language, making it suitable for students and professionals seeking to understand the fundamentals of web communication.

Typology: Study notes

2023/2024

Available from 12/16/2024

mariam-ibrahim-7 🇨🇦

5 documents

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Web and HTTP

eachwebpageconsistsof anumberofobjectsthe

base

objectistypically an HTMLfileand

thenin

eachfileembedes

areseveralreferencedobjects ex another

HTML

file

Cssimageaudio

file

etc each

objectisaddressed

byaURL

Tam e

HTTPhypertexttransfer

protocol web'sapplication

layer

protocol inclient

server

model

clientbrowser

thatrequsts

receives

objectsusing

HTTP

protocols and displays webobjects HTMLinterpreter's

job

to

display

serverrecieves requests andsends back

the response objectusingHTTP

protocol

HTTP

usesTCPclientinitiates aTCP connection using

default

port

80 server

then accepts the connection

and

thenclientbegins tosend HTTPrequest serverthen

sends

back an HTTP

responsethen TCPthtltionthioses

Nonpersistent HTTP sending

onlyoneobject

perTCP

connectionand

close

connectiontodownloadmultipleobjects uneed

tocreatemultipleTCPconnections

PersistentHTTPreusing

the

TCPconnectionthat

wasstartedto

send

multipleobjects

until

tone

thencloses

Nonpersistent HTTP host

name path filename

soooooooo

times

Partial preview of the text

Download Web and HTTP Protocols: A Comprehensive Overview and more Study notes Engineering in PDF only on Docsity!

Web

and HTTP

each webpage

consists

of

a

number

of

objects

the

baseobject is

typically an

HTML

file

and then

in

each

file

embedes

are

several

referenced objects

ex

another HTML

file

Css

imageaudiofileetc

eachobject

is

addressed

by

a

URL

Tame

HTTP

hypertext

transfer

protocol

web's application

layer

protocol

in

clientserver

model

clientbrowser

that

requstsreceives objects

using

HTTPprotocols

and

displays web

objects HTMLinterpreter's

job

to

display

server

recieves requests and

sends back the response objectusing

HTTPprotocol

HTTP

usesTCPclient

initiates

a

TCP

connection

using

default

port

server

then accepts the

connection

andthenclient begins to

send HTTP request server

thensends back

an

HTTPresponse

then

TCP

thtltionthioses

Non persistent HTTP sending

only

one

object

per

TCP

connection and

close

connection

to

download

multipleobjects u

need

to

create multiple

TCP

connections

Persistent HTTP

reusingthe

TCP

connection

thatwas

started

to

send multiple

objects

until

tonethencloses then

closes

Non persistent HTTP

hostname path

filename

soooooooo

times

MATT

thetime for

a smallpacket request

msg

totravel

from client to

server

and

back as a response

msg

entens delay w

otransmoon

Nonpersistent

RTT

one

RTT

to

initiate

TCP

connection

one

RTT

for

HTTP request

thefirstfewbytesof

HTTP

response to return

object

file

transmission

time

accepthorn

non

persistentresponsetime 2

RTT

file

transmission

time

Has

forHTML

w 10 imagesit'll

take

RTT

11 file

transmission time

Persistent

RTT

server

leaves

connection

open

until

done requesting 8

receiving

persistentresponsetime

2

RTT file

transmission time

for

HTML

w 10 images

it'll

take

TCP

connection RTT

11 RTTfor

requests

transmission

times

vs

HTTP

response message

HTTP

response

status

codes

resirecting

Not

inserver anymore

Web

cashes

help

reduce

delay

of

requesting

receiving

objects

by

storing

them

in

its

own

storage disk

it

keeps

copies of

recently requested objects

in

localstorage

if

object

is in

cashe

gives

the object to

client w

o

going

to server

else cashe

requests

the

object

from server then

gives

to

client

preserver

why

web cashing

reduces

response time

retures

delay

8

traffic

Webcashe

acts

like

both client

server

Cashe

example

PR

My

La

097

reteap

I

asa

E mail

8 SMTP

three

major

components

User

agents the

software

running

onthe

machine

closer to the

users ex

Outlook

they

allow us

to

write

edit

read

emails

the

actual

emails

are all

stored

on the

servers

not

useragent

mail

servers the

software

running

on

machines

farther

away

fromusers

mailbox contains

all

the

users

incomingmags

message queue

the

outgoing

msgs

are

stored theretemporarly waiting

forthe recievingmailservertoopen

up

andaccept

the

emails

SMTP simple mail

transferprotocol allows

sendingserver receivingserverto

communicate

one

state

client

sending mail

server

server receiving

mail server

SMTP uses

TCP

to

reliably

transfer

email

msys

cuzthey're

mostly

texts

fromclient

to

server on

port

25

direct

transfer

sending

server acts like

theclientto

recur server

three

phases

of

SMTP

handshaking

SMTPtransfer

of

messages

SMTPclosure

the

msg

are

js

comments

response

like

HTTP

commands

in

ASCII

texts response in

status code

8

phrase

Scenario

C

S

SMTP

SMTP HIRE

always on

Sample

SMTPinteraction

Water

I'm

ready 8

my

name is

bobschool.edu

hello

sender

www.f

I'm

readyto

send data

data

immtstora

unsay

closing

DNS

domain

name

system

DNS

is

like

a phone

book

it has

machine webs names 8

their

corresponding

IP

addresses

IP

addresses

are for

computers

to

understand

thenameis

for usto

understand

So

DNS

is

used

to

identify

the maping bet

name

8 IP so

we

both

understand

distributed

database

implemented

in a

hierarchy of

many

name

servers

they

work w application

layer

protocol

hosts DNSservers

communicate

to

resolve names

address

name

translation

runs in

theendsystems

not

core

routers

so

canchangeez

DNS

services

host

name

to

IP

address translation

host

aliasing

some

host names rstill long

canonical

so

wemake a

simplecute aliasname

mailserver

aliasing

load

distribution

Hierarchical database

ex

when

a

host makes

a

DNS

query

it

is sent

to it's

local DNS

server

which

if

translation

out of

date

it

forwards

therequest

into

DNS

hierarchy

for

resolution

iterated

query

Edema

fintifthanam

recursive

query

puts

a

burden

on

rootserver

heavy

load at

upper

level

YNYMMMMM

apass ittowin

Transport

Layer

services provide a

logical

communication channel between two processes running on

dif

hosts

end systems

senderside breaks

application

msys

into

smaller

parts

adds

a

header toeach

part

making

them

into

segments

receiversidetakes segmentsfrom

network

layer

reassembles these segments back

to

theoriginal message 8 gets

passed

up

to

application

layer

that

breaking ofthe

segments 8 passing

them and

reassembling them

are

implemented

using

TCP

and

UDP

Transport

layer

workscloselywith

application

layer

8

network

layer

they

establish

logical

communictions between

processes

relies on underlying

network

layer

services

ex a

processsenting

to

another

how

does

the sending

process

knowwhich

way

to

pass

it

down

thats

the

network

layer's

job

Network

Tiger

protocols

they

provide

communication between hosts enables sending

of

segments

thru

the

internet and reaching

the

other

destination

host

Transport protocols

Ttm

does

reliable

and in

order delivery the

packets

willbe

controlled

if

theres congestion then

it

contro

the

sending of

packets

by

slowing

it

down

flow

control helps not

overwhelm

the

receiver

sidebuffer

its

a

connection

oriented service

that

takes

some

time

Wtpprt

unreliable

unordered

delivery

both neither

of

them

has

full

delay

guarantee or security garantee or

bandwidth

guarantee

Multiplexing De multiplexing sending out

packets

figuringout

who

it belongs

to

sents it out

to

other

receives

the

packets

application

layers

figures

out

whothey

belong

toto

hand

out

needs ports

to

Mentry

in

transport

layer

demultiplexing

is more

complex

so

host

receives

IP datagrams each

datagram

has

a

source

IP

address

and a

destination

IP

address

each

datagram carries one transport

layer

segment

each

segment

has a

source 8

destination

port

s

network

taperinfo

transport

layer

segment

Connection

oriented

demultiplexing

by

a

TCP

connection

the

TCP

socket is

identified

by

source

IP

address

source

port

test IP

address

test

port

uses

all

of

these

to direct the segment

to

the

appropriate

socket

TCP

server

supports

many

sockets

each socket is

associated

with a

different

connecting

client

identified

by

it's own 4 tuple

server

client client

Summary

Tophat

qs

2

requests 200 client

f

3

server

file

1sec cache

cache

012sec

TCP

connection

in cache 0,

C

Steache

client

cache

200

0.1 0.

RTT

8 back

24sec

Ioe

TCP

connection

3sec

cache

server 8 bark

cache

Groveton

200

TT

Et

20013

wFdEEt

Tt

seconds

Web and HTTP Protocols: A Comprehensive Overview, Study notes of Engineering

Related documents

Partial preview of the text

Download Web and HTTP Protocols: A Comprehensive Overview and more Study notes Engineering in PDF only on Docsity!

Web

of

of

the

file

in

file

file

imageaudiofileetc

URL

recieves requests and

TCP

TCP

only

TCP

to

TCP

TCP

totravel

Nonpersistent

RTT

TCP

for

thefirstfewbytesof

response to return

persistentresponsetime 2

RTT

time

forHTML

w 10 imagesit'll

RTT

11 file

until

RTT file

HTML

it'll

take

TCP

11 RTTfor

HTTP

HTTP

status

cashes

delay

receiving

objects

storing

own

storage disk

it

copies of

recently requested objects

localstorage

if

object

cashe

gives

client w

going

to server

else cashe

object

why

reduces

Webcashe

acts

both client

PR

I

three

major

User

agents the

closer to the

they

to