Wilamowski B.M., Irwin J.D. The Industrial Electronics Handbook. Second Edition: Industrial Communication Systems

Подождите немного. Документ загружается.

61-10 Industrial Communication Systems

61.2.7 Error Control

TCP.as.a.reliable.protocol.that.uses.unreliable.underlying.IP.must.implement.error.control.. is.error.

control.includes.detecting.lost.segments,.out-of-order.segments,.corrupted.segments,.and.duplicated.

segments..Aer.detection,.the.error.must.be.corrected.. e.error.detection.is.implemented.by.using.

three.features:.segment.checksum,.segment.acknowledgment,.and.time-out..Segments.with.incorrect

checksum

.(Figure.61.9a). are. discarded.. Since. TCP. uses.only. positive.acknowledgment,. no.negative.

acknowledgment.can.be.sent,.and.both.the.corrupted.segment.error.and.the.lost segment.(Figure.61.9b).

error.are.detected.by.time-out.for.receiving.an.acknowledgment.by.the.sender.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Threshold

Congestion window size

Time-out

New threshold

Number of transmitted segments(a)

(b)

Sender Receiver

Segment 1

Segment 2

Time Time

Buffer

1000

5000

4000

seq:2001,5000 bytes

ack:7001 win:0

ack:7001 win:1000

seq:7001,1000 bytes

FIGURE 61.8 Congestion.Control.Window.Size..Sender.side.(a).(upper/le),.receiver.side.control.(b).(lower/right).

Transmission Control Protocol—TCP 61-11

 e.error.correction.is.implemented.by.establishing.a.time-out counter.for.each.segment.sent..If.the.

acknowledgment.is.received,.then.the.particular.and.all.preceding.counters.and.the.segments.are.dis-

posed.

.If.the.counter.reaches.time-out,.then.the.segment.is.resent.and.the.timer.is.reset.

.duplicate segment.can.be.created.if.the.acknowledgment.segment.is.lost.or.is.delayed.too.much..

Since.data.are.reassembled.into.a.byte-stream.at.the.destination,.data.from.the.duplicate.segment.is.

already.in.the.buer.. e.duplicate.segment.is.discarded..No.acknowledgment.is.sent.

. out-of-order segment. is. stored. but. not. acknowledged. before. all. segments. that. precede. it. are.

received.. is.may.cause.resending.the.segments.. e.duplicates.are.discarded.

.case.of.lost acknowledgment.(Figure.61.9c),.the.error.is.corrected.when.the.acknowledgment.for.

the.next.segment.is.sent,.since.an.acknowledgment.to.the.next.segment.also.acknowledges.all.previous.

segments.. erefore,.a.lost.acknowledgment.may.not.be.noticed.at.all.. is.could.generate.a.deadlock.

in.case.if.the.acknowledgment.is.sent.on.the.last.segment.and.for.a.time.when.there.is.no.more.seg-

ments

.to.send.. is.deadlock.is.corrected.by.a.sender.that.uses.a.so-called.persistence timer..If.no.

acknowledgment.comes.within.a.certain.time.frame,.then.the.sender.sends.a.1.byte.segment.called.

probe.and.resets.the.persistence.counter..With.each.attempt,.the.persistence.timer.time-out.is.doubled.

until.60.s.time.is.reached..Aer.receiving.an.acknowledgment,.the.persistence.timer.time-out.is.reset.

to.the.initial.value.

Keep-alive timer

.is.used.to.prevent.a.long.idle.connection..If.no.segments.are.exchanged.for.a.given.

period.of.time,.usually.2.h,.the.server.send.a.probe..If.there.is.no.response.aer.10.probes.the.connection.

is.reset.and.thus.terminated.

Sender

Receiver

Segment 1

Segment 2

Segment 3

Segment 3, retransmitted

ack:2601

ack:2801

Segment 3

corrupted

seq:2601,200 bytes

seq:2401,200 bytes

seq:2201,200 bytes

OK OK

Time

Time-out

Time

(a)

Sender

Receiver

Segment 3

lost

Segment 1

Segment 2

Segment 3

Segment 3, retransmitted

ack:3601

ack:3801

seq:3601,200 bytes

seq:3401,200 bytes

seq:3201,200 bytes

OK OK

Time

Time-out

Time

(b)

Sender

Receiver

Acknowledgment

lost

ack:4801

ack:4601

seq:4201,200 bytes

seq:4401,200 bytes

seq:4601,200 bytes

OK OK OK

Time Time

(c)

FIGURE 61.9 Corrupted.segment.(a),.lost.segment.(b),.and.lost.acknowledgment.(c).

61-12 Industrial Communication Systems

Time-waited timer.is.used.during.the.connection.termination.procedure.that.is.described.later..If.

the

.is.no.ack

nowledgment

.to.the.FIN.seg

ment,

.the.FIN.seg

ment

.is.res

ent

.ae

.tim

e-waited

.tim

exp

ires.

.Du

plicate

.FI

.se

gments

.ar

.di

scarded

.by.th

.de

stination.

61.2.8 Congestion Control

In.case.of.the.congestion.on.the.network,.packets.could.be.dropped.by.routers..TCP.assumes.that.the.cause.

of.a.los

.segm

ent

.is.due.to.the.net

work

.con

gestion.

. er

efore,

.an.add

itional

.mech

anism

.is.bui

.in.int

.TCP.

to.pre

vent

.pro

mpt

.rese

nding

.of.pac

kets

.and.cre

ating

.eve

.mor

.con

gestion.

. is.mech

anism

.is.imp

le-

mented

.by.add

itional

.con

trol

.of.the.send

.win

dow,

.as.desc

ribed

.bel

.and.ill

ustrated

.in.Fig

ure

.61.

8a.

•

. e.sen

der

.win

dow

.size.is.alw

ays

.set.to.the.sma

ller

.of.the.two.val

ues—the

.rec

eiver

.win

dow

.size.

and.th

.co

ngestion window size.

•

. e.co

ngestion

.wi

ndow

.siz

.st

arts

.at.th

.siz

.of.tw

.ma

ximum

.se

gments.

•

. Wit

.each.rec

eived

.ack

nowledgment,

.the.con

gestion

.win

dow

.siz

.is.dou

bled

.unt

.cer

tain

.thr

eshold.

Ae

.re

aching

.th

reshold

.th

.fu

rther

.in

crease

.is.ad

ditive.

•

. Wit

.eac

.ack

nowledgment

.tim

.out

.the.thr

eshold

.is.red

uced

.by.hal

.and.the.con

gestion

win

dow

.siz

.is.res

.to.the.ini

tial

.siz

.of.two.max

imum

.seg

ment

.siz

61.2.9 Connection termination

Any.of.the.two.application.processes.that.established.a.TCP.connection.can.close.that.connection..

Whe

.a.con

nection

.in.one.dir

ection

.is.ter

minated,

.the.oth

.dir

ection

.is.sti

.fun

ctional,

.unt

.the.sec

ond

.pro

cess

.als

.ter

minates

.it.. er

efore,

.fou

.act

ions

.mus

.be.per

formed

.to.clo

.the.con

nection

.in.

bot

.di

rections:

. 1.. Hos

.A.(ei

ther

.cli

ent

.or.serv

er)

.send

.a.segm

ent

.ann

ouncing

.tha

.it.wan

.to.ter

minate

.the.con

nection.

. 2.. Hos

.B.sen

.a.seg

ment

.ack

nowledging

.the.req

uest

.of.A..At.thi

.mom

ent,

.the.con

nection

.fro

A.to.B.is.clo

sed,

.but.fro

.B.to.A.is.sti

.ope

. 3..Whe

.hos

.B.is.rea

.to.ter

minate

.the.con

nection,

.for.exa

mple,

.ae

.sen

ding

.the.rem

aining

.dat

it.se

nds

.a.se

gment

.an

nouncing

.th

.it.wa

nts

.to.te

rminate

.th

.co

nnection

.as.we

ll.

. 4.. Host.A.sends.a.segment.acknowledging.the.request.of.B..At.this.moment,.the.connection.in.both.

dir

ections

.is.cl

osed.

Unlike

.in.cas

.of.ope

ning

.the.con

nection,

.non

.of.the.ste

.can.be.comb

ined

.into.one.seg

ment.

efore,

. the. con

nection

. ter

mination

. des

cribed

. is. als

. cal

led

. fou

r-way handshaking.

. Fig

ure

. 61.

ill

ustrates

.an.exa

mple

.of.seg

ment

.exc

hange

.dur

ing

.con

nection

.ter

mination.

.Bec

ause

.it.doe

.not.mat

ter

whi

.ho

.is.a.se

rver

.an

.wh

ich

.is.a.cl

ient,

.th

.ar

.de

noted

.on

.as.A.an

.B.

. 1..Hos

.A.se

nds

.a.se

gment

.wi

.FI

.bi

.se

. 2.. Hos

.B.se

nds

.a.se

gment

.wi

.AC

.bi

.se

.to.co

nrm

.re

ceiving

.th

.FI

.se

gment

.fr

.ho

.A.

. 3.. Hos

.B.may.con

tinue

.to.sen

.dat

.and.exp

ect

.to.rec

eive

.ack

nowledgment

.mes

sages

.wit

.no.

dat

.fro

.hos

.A..Eve

ntually,

.whe

.the

.is.not

hing

.mor

.to.sen

.it.sen

.a.seg

ment

.wit

FIN.bit.set

. 4.. Hos

.A.sen

.the.las

.seg

ment

.in.the.tra

nsmission

.wit

.ACK.bit.set.to.con

rm

.rec

eiving

.the.FIN.

seg

ment

.fr

.ho

.B.

.con

nection

.ter

mination

.pro

cedure

.des

cribed

.abo

.is.so-

called

.as.gra

ceful

.ter

mination.

.In.

cer

tain

.cas

es,

.the.con

nection

.may.be.ter

minated

.abr

uptly

.by.res

etting.

. is.may.hap

pen

.in.the.fol

lowing

.cas

es:

•

. e.cli

ent

.pro

cess

.req

uested

.a.con

nection

.to.a.non

existent

.por

. e.TCP.lib

rary,

.on.the.oth

side

.ma

.se

.a.se

gment

.wi

.th

.RS

.bi

.se

.to.in

dicate

.co

nnection

.re

fusal.

Transmission Control Protocol—TCP 61-13

•. One.of.the.processes.wants.to.abandon.the.connection.because.of.an.abnormal.situation..It.can.

send.the.RST.segment.to.destroy.the.connection.

•

. One.of.the.processes.determines.that.the.other.side.is.idle.for.a.long.time.. e.other.system.is.

considered.idle.if.it.does.not.send.any.data,.any.acknowledgments,.or.keep-alive.segments.. e.

awaiting.process.may.send.the.RST.segment.to.destroy.the.connection.

Sender

Receiver

Time

Segment 1: FIN

Segment 3: FIN

Segment 2: ACK

Segment 4: ACK

seq:12500, ack:--

seq:5000, ack:12501

seq:5001, ack:12501

seq:12501, ack:5002

FIGURE 61.10 Four-way.handshaking.during.connection.termination.

Closed

Listen

SYN-SENT

SYN-RCVD

Active open/SYN

Close/--

RST/--

Passive open/--

SYN/SYN+ACK

(Simultaneous open)

Established

ACK/--

ACK/--ACK/--

Close/FIN

Close/

FIN

FIN/ACK

(Time-out)

FIN+ACK/ACK

Send/SYNRST/--

Time-out/RST

time-out /--

SYN+ACK/ACK

ACK/--

Close or

Closing

wait

Last

ack

Time-

wait

FIN

wait-2

FIN

wait-1

FIGURE 61.11 TCP.state.transition.diagram.

61-14 Industrial Communication Systems

61.3 State Diagram

 e.state.transition.diagram.for.soware.that.implements.TCP.is.presented..Figure.61.11.shows.the.state.

transition.diagram.for.the.server.and.for.the.client.. e.dashed.lines.indicate.transitions.in.a.server..

 e.solid.lines.indicate.transitions.in.a.client.

61.4 Programming Samples

Figures.61.12.and.61.13.contain.two.C.programs.that.demonstrate.the.use.of.TCP.for.communication.

using.client–server.paradigm.[C02-3]..Socket.API.is.a.de facto.standard..Programs.use.conditional.

compilation.directives.that.include.minor.variations.in.the.library.headers.needed.for.operation.under.

(a)

FIGURE 61.12 Sample.C.program.that.illustrates.a.TCP.server.(a),.(b).

Transmission Control Protocol—TCP 61-15

Unix/Linux.and.Windows..Function.calls.should.be.modied.if.desired.to.run.under.other.operating.

systems.or.with.proprietary.operating.systems.for.embedded.devices..Minor.modications.need.to.be.

performed.when.utilizing.underlying.IPv6.API,.as.described.in.[RFC3493]..Figure.61.12.shows.the.server.

program.that.waits.for.the.incoming.connection.from.the.client.program.listed.in.Figure.61.13..To.allow.

maximum.compatibility,.the.sample.server.does.not.use.multithreading.when.servicing.client.connec-

tions,

.thus.allowing.only.one.connection.at.a.time..However,.such.modication.can.be.easily.made.by.

relocating.code.for.servicing.a.client.(marked.by.comments).into.a.function.run.in.a.separate.thread,.each.

time.a.new.client.is.connected..Programs.show.all.steps.necessary.to.set-up,.use,.and.tear.down.a.TCP.

connection.

Internet

.socket.is.an.end.point.of.a.bidirectional.interprocess.communication.ow.across.an.IP-based.

computer.network..Interface.to.the.socket.library.is.standardized.only.on.Unix/Linux.and.Windows..

Other.operating.systems,.including.various.embedded.systems,.may.employ.dierent.functions.to.carry.

out.the.same.functionality..Programs.of.the.same.functionality.implemented.in.other.languages.may.

combine.several.steps.into.calling.a.single.function.. is.is.especially.true.for.the.socket.initialization.

and.connection.set.up.

(b)

FIGURE 61.12 (continued)

61-16 Industrial Communication Systems

FIGURE 61.13 Sample.C.program.that.illustrates.a.TCP.client.

Transmission Control Protocol—TCP 61-17

references

[C02–1].D..Comer,.Internetworking with TCP/IP,.Vol..1:.Principles, Protocols, and Architecture,.5th.edn.,.

Pren

tice

.Ha

ll,

.Up

per

.Saddle.Ri

ver,

.NJ,.2005.

[C02-3]

.D..Com

.et.al.,.Int

ernetworking with TCP/IP,

.Vol

.III:.Clien

t-Server Programming and Applications,

Linux/Posix Sockets Version,

.Pr

entice

.Ha

ll,

.Up

per

.Saddle.Ri

ver,

.NJ,.2000.

[F10]

.B.A..Fo

rouzan,

.TCP/IP P

rotocol Suite,

.4th.edn.,.McG

raw-Hill,

.Ne

.Yo

rk,

.2010.

[GW03]

.A..Le

on-Garcia,

.I..Wid

jaja,

.Co

mmunication Networks,

.2nd.edn.,.McG

raw-Hill,

.Ne

.Yo

rk,

.2003.

[IAN

.We

.Si

.fo

.IAN

A—Internet

.As

signed

.Num

bers

.Au

thority,

.ht

tp://www.iana.org/

[PD07]

.L.L..Peter

son,

.B.S..Dav

ie,

.Com

puter Networks: A System Approach,

.4th.edn.,.Mor

gan

.Kauf

mann

Publi

shers,

.San.Fra

ncisco,

.CA,.2007.

[RFC]

.We

.Si

.fo

.RFC Edi

tor,

.ht

tp://www.rfc-editor.org/

[RFC813]

.D..Cla

rk,

.Win

dow

.and.Ack

nowledgement

.Str

ategy

.in.TCP

.Jul

.198

.htt

p://www.rfc-editor.org/

[RFC896]

.J..Nag

le,

.Con

gestion

.Con

trol

.in.IP/

TCP

.Int

ernetworks,

.Jan

uary

.198

.htt

p://www.rfc-editor.org/

[RFC2147]

.D..Bor

man

.et.al.,.TCP.and.UDP.over.IPv6.Jumb

ograms,

.May.1997,.htt

p://www.rfc-editor.org/

[RFC2525]

.V..Pax

son

.et.al.

.Kno

.TCP.Imp

lementation

.Pro

blems,

.Mar

.199

.htt

p://www.rfc-editor.org/

[RFC2675]

.D..Bo

rman

.et.al

.IPv6.Jum

bograms,

.Augu

.1999,.ht

tp://www.rfc-editor.org/

[RFC2757]

.G..Mo

ntenegro

.et.al

.Lo

. in.Net

works,

.Ja

nuary

.2000,.ht

tp://www.rfc-editor.org/

[RFC3493]

.R..Gil

ligan

.et.al.

.Bas

.Soc

ket

.Int

erface

.Ext

ensions

.for.IPv

.Feb

ruary

.200

.htt

p://www.

rfc-editor.org/

[STD2]

.J..Re

ynolds,

.J..Pos

tel,

.As

signed

.Num

bers,

.Oc

tober

.1994,.ht

tp://www.rfc-editor.org/

[STD5]

.J..Postel,.Internet.Protocol,.September.1981,.http://www.rfc-editor.org/

[STD7]

.RFC0793/STD0007,.J..Post

.(ed.),.Tran

smission

.Con

trol

.Pro

tocol

.DARPA.Int

ernet

.Prog

ram

Pro

tocol

.Sp

ecication,

.Sep

tember

.1981,.ht

tp://www.rfc-editor.org/

62-1

62.1 Introduction

A.static.Web.site,.which.is.generally.written.in.HTML,.does.not.provide.the.functionality.to.dynami-

cally

.extr

act

.the.info

rmation

.beca

use

.stat

.Web.sites.do.not.store.info

rmation

.in.a.data

base,

.lack

ing

.the.

func

tionality

.need

.for.dyna

mic

.Web.sites

.In.most.case

.beca

use

.stat

.Web.page

.do.not.carr

.larg

amou

.of.inf

ormation,

.all.the.inf

ormation

.is.embe

dded

.in.the.sta

tic

.Web.site

Dynamic

.Web.sites.[3].inte

ract

.dyna

mically

.with.the.clie

.by.taki

.requ

ests

.from.the.clie

nt,

.send

ing

.them.to.the.serv

.for.proc

essing,

.and.disp

laying

.the.resu

lts

.on.the.Web.page

.Mean

while,

.the.serv

inte

racts

.with.the.data

base

.to.extr

act

.the.info

rmation

.requ

ired

.for.the.user

.form

ats

.the.info

rmation

so.that.the.user.can.read.it,.and.send

.it.back.to.the.clie

.brow

ser.

.HTML.alon

.does.not.prov

ide

.the.

func

tionality

.need

.for.a.dyna

mic,

.inte

ractive

.envi

ronment.

. e.most.comm

.scri

pting

.lang

uages

used.for.deve

loping

.dyna

mic

.Web.sites.are.PHP,.Perl

.and.Pyth

on.

.Figu

.62.1.show

.the.data.ow.in.a.

dyna

mic,

.int

eractive

.cli

ent-server

.env

ironment.

PHP,

.a.serv

er-side

.scri

pting

.lang

uage,

.is.the.most.popu

lar

.tech

nology

.that.is.espe

cially

.suit

.for.

deve

loping

.dyna

mic,

.inte

ractive

.Web.sites

.PHP,.whic

.orig

inally

.stood.for.“per

sonal

.home.page

,”

.and.is.

an.open

-source

.sow

are

.init

ially

.crea

ted

.to.repl

ace

.a.smal

.set.of.Perl.scri

pts

.that.had.been.used.in.Web.

sites

.Grad

ually

.PHP.beca

.a.gene

ral

.purp

ose

.scri

pting

.lang

uage

.that.is.used.espe

cially

.for.Web.deve

opment

.and.now.call

.“hyp

ertext

.prep

rocessor.”

.PHP.is.embed

ded

.into.HTML.and.inte

rpreted

.on.a.

Web.serv

.con

gured

.to.oper

ate

.PHP.scri

pts.

.PHP.is.a.serv

er-side

.scri

pting

.lang

uage

.simil

.to.othe

serv

er-side

.scri

pting

.lang

uages

.like.Micr

oso’s

.Acti

.Serv

.Page

.and.Sun.Micr

osystems’

.Java

Server

Page

[1].

PHP

rese

mbles

synt

and

PERL

main

die

rence

betw

een

PHP

and

PERL

lays

the.set.of.stan

dards

.buil

.in.libr

aries

.that.supp

ort

.the.gene

rations

.of.HTML.code

.proc

essing

.data.from.

and.to.the.Web.serv

er,

.and.hand

ling

.cook

ies

.[4]..PHP.is.used.in.conj

unction

.with.data

base

.syst

ems,

.such.

Development of

Interactive Web Pages

62.1. Introduction.....................................................................................62-1

62.2

. Inst

allations......................................................................................62-2

WAMP.Server

62.3. Introduction.to.PHP........................................................................62-3

Variables. •. Conditional.Statements. •. Loops. •. .

Functions. •. Include.Function. •. $_GET.and.$_POST.function

62.4. MySQL...............................................................................................62-7

Creating.a.Database. •. Creating.a.Table. •. Modifying.Tables

62.5. Creating.Dynamic.Web.Sites.Using.PHP.and.MySQL............62-10

Connecting.to.Database. •. SQL.Queries.with.PHP. •. Creating.

aDatabase. •. Creating.a.Table. •. Insert,.Update.and.Delete.queries

References................................................................................................... 62-14

Pradeep Dandamudi

Auburn University

62-2 Industrial Communication Systems

as,.PostgreSQL,.Oracle,.MySQL,.to.create.powerful.and.dynamic.server-side.applications..Signicant.

Web.site

.tha

.are.wri

tten

.in.PHP.inc

lude

.Joo

mla,

.Dru

pal,

.Wor

dPress,

.Fac

ebook,

.etc

Database

.come

.to.pict

ure

.when.it.come

.to.stori

.huge.amou

.of.info

rmation

.and.retr

ieving

.the.

info

rmation

.back.when.need

.by.the.Web.site.. e.data

base

.can.cont

ain

.info

rmation

.coll

ected

.from.

the.user.or.from.the.admi

nistrator.

.MySQ

.(wri

tten

.in.C.and.C++).is.an.open

-source

.rela

tional

.data

base

mana

gement

.syst

.(RDB

MS)

.that.is.base

.on.the.stru

cture

.quer

.lang

uage

.(SQL

)

.for.proc

essing

.the.

data.in.the.data

base

.and.mana

ges

.mult

iuser

.acce

.to.a.numbe

.of.data

bases.

.In.a.rela

tional

.data

base,

ther

.are.tabl

.that.store.data

. e.colu

mns

.den

.what.kind.of.info

rmation

.will.be.store

.in.the.tabl

and.a.row.cont

ains

.the.actu

.valu

.for.thes

.spec

ied

.colu

mns.

. e.lang

uage

.prov

ides

.a.stan

dard

synt

.for.acce

ssing

.rela

tional

.data

bases.

.MySQ

.work

.on.many.die

rent

.syst

.plat

forms,

.incl

uding

Linu

.Mac.OS.X,.Mic

roso

.Wind

ows,

.Ope

nSolaris

.and.man

.oth

ers.

PHP

.(hyp

ertext

.prep

rocessor)

.and.MySQ

.(a.port

able

.SQL.serv

er)

.toget

her

.have.made.the.task.of.

buil

ding

.and.acce

ssing

.rela

tional

.data

bases

.much.easie

.[2].. is.chapt

.intr

oduces

.you.to.PHP.and.

MySQ

.and.exp

lains

.how.to.use.the

.two.toge

ther

.in.ord

.to.bui

.dyn

amic

.Web.site

.[7]

62.2 Installations

Before.you.begin.to.design.a.Web.site,.you.need.to.set.up.an.environment.that.facilitates.your.develop-

ment.

.You.can.set.up.a.tes

.site.on.you

.com

puter

.by.loc

ally

.ins

talling

.the.fol

lowing

.so

wares.

. 1..Apac

he—an

.ope

n-source

.Web.ser

ver

. Down

load

.fro

.htt

p://tomcat.apache.org/index.html

. 2.. PHP—

.ope

n-source

.gen

eral

.pur

pose

.scr

ipting

.lan

guage

.desi

gned

.spe

cically

.for.the.Web

. Down

load

.fro

.www

.php.net/

. 3..MySQ

L—an

.ope

.sou

rce

.dat

abase

.man

agement

.sys

tem

. Down

load

.fro

.www

.mysql.com/

Aer

.the.abov

.sow

ares

.are.down

loaded

.and.inst

alled,

.you.need.to.con

gure

.the.Apac

.serv

.to.

process.the.PHP.code..You.also.need.to.create.an.MySQL.account.in.order.to.use.it.in.your.PHP.code..

Some

times

.you.may.nd.it.dic

ult

.to.inst

all

.and.con

gure

.thes

.sow

ares

.but.the.Web.sites.wher

.you.

down

load

.the.sow

are

.will.prov

ide

.you.with.gene

ral

.inst

ructions

.to.inst

all

.and.con

gure

.them

.If.you.

nd.it.dic

ult

.to.inst

all

.thes

.sow

ares

.will.it.woul

.be.easie

.for.you.to.nd.sow

are

.pack

ages

.(oe

call

.sow

are

.bund

les)

.that.can.inst

all

.and.con

gure

.them.autom

atically.

.A.few.sow

are

.pack

ages

of.inde

pendently

.crea

ted

.prog

rams

.are.WAMP.serv

.(for.Windo

.envi

ronment),

.LAMP.serv

.(for.

Linu

.use

rs),

.MAM

.ser

ver

.(fo

.Mac.OS).and.SAM

.ser

ver

.(fo

.Sol

aris

.OS)

62.2.1 WaMP Server

WAMP.is.an.open-source.soware.used.to.run.dynamic.Web.sites.on.the.Windows.environment.. e.

WAMP.pack

age

.prin

cipal

.comp

onents

.are:.Apac

.Web.serv

er,

.MySQ

.data

base

.mana

gement

.syst

em,

PHP.(or.Per

l/Python)

.scr

ipting

.lan

guages

.and.Php

MyAdmin.

Client side

Web Browser

e.g. Firefox, IE, etc.

HTML, CSS, JavaScript

Interpreter

Database

HTTP

Daemon

CGI

PHP scripts,

Perl scripts, etc.

Server side

FIGURE 62.1 Data.ow.in.a.client–server.partition.