软件是计算机的灵魂

PARTIIntroductiontothe

FoundationofInformation

Technologies

Session7

ComputerSoftware

SOFTWARE

软件是计算机的灵魂”

PROGRAM:Setofinstructionstothecomputer

STORED:Programmustbeinprimarystorage

Software:Detailedinstructionstocontrolcomputer

operationofacomputersystems.Withoutsoftware,the

computerhardwarecouldnotperformanytasks.The

functionsofsoftwareareto

(1)managethecomputerresourcesoftheorganization,

(2)providetoolsfbrhumanbeingstotakeadvantageofthethese

resources

(3)actasintermediarybetweenorganizationsandstored

information.

APPLICATIONSOFTWARE

Generalizedprogramsthat

SYSTEMSOFTWAREmanagetheresourcesof

thecomputer,including

-OperatingSystem:

HARDWARE

•Scheduledcomputerevent

•Allocatescomputer

resources

•Monitorsevents

-Languagetranslators:

•Interpreters

•Compilers

-UtilityPrograms:

•Routineoperations

•Managedata

Programswrittenforaspecificapplicationtoperformfunctions

specifiedbyendusers.

-ProgrammingLanguage

-softwarepackage

Operatingsystem

•Allocatesandassigns:

-memory

»e.g.,filesystem,virtualmemory

-processortime

»e.g.,multitasking,multiprocessing

-input-outputdevices

»e.g.,printer,keyboard,etc.

•Mayalsoprovideothercapabilitiesusefulto

manyusersorprograms

-GraphicalUserInterface(GUI)capabilities

-Fonts,networkprotocols,...

peratingsystemasmagician(魔术师)

•Thefourillusions

-Manyseparatecomputers,oneforeachprocess

—“Multitasking”

一Largememory-"Virtualmemory”

-Disksandothersecondarystorageare

organizedascollectionsoffiles-"Filesystems”

-Windowsandmenus-"GraphicalUser

Interface(GUI)”

^OperatingSystemsCapabilities:

MultiprogrammingsMultitasking

TRADITIONALSINGLE-MULTIPROGRAMMING

PROGRAMSYSTEMENVIRONMENT

ratingSystemsCapabilities:

VirtualStorage

•VirtualStorageisthemethodofhandling

severalprogramsinprimarystorage:

-Programdividedinto

•Fixedlengthportions(pages)OR

•Variablelength(segments)

-Currentportionsresideinprimarystorage,

portionsswappedoutwhendone.

^^eratingSystemsCapabilities:

timesharing

MANYUSERSSHARELARGECPU:

•TimeinCPUdividedintoslices(e.g.:2

microseconds)

•EachuserhasaccesstoCPUduringslice.

•SingleCPUisfast,candomuchduring

timeslice

Usersjobswappedoutatendofslice

箭ratingSystemsCapabilities:

MMultiprocessing

•LinkstogethertwoormoreCPUstowork

inparallelinasinglecomputersystemsto

executetwoormoreinstructions.

-Programcanbedividedtobeprocessedby

multipleCPUs.

-Canprocesslargeprogramsmorerapidly

*,

peratingSystemsCapabilities:

FileSystems

•Reality:

-Disksaresetsoftracks（磁道）

-Tracksaresetsofsectors（扇区）

-Sectorscanstorefixed-sizedbyteblocks

•Illusion:

-Disksaresetsofdirectories（目录）

-Directoriescontainotherdirectoriesorfiles

-Filesarevariable-sizebytesequences

-Directoriesandfileshavenames

^^feperatingSystemsCapabilities:

JWindowsandMenus

•Reality:Screenisanarrayofpixels（象素数组）

•Illusion1:Menus

-Dependingonwhereyouclick,differentaction

happens

-Technique:OSlooksuplocationwheremousewas

clicked,executesappropriateaction

•Illusion2:Overlappingwindows

-Awindowmaycoverpartorallofanother

-Whenawindowisuncovered,itscontentsare

redisplayed

-Technique:OSsavesbitmap（位图）ofcovered

windows

»Applicationdoesnotneedtoknowhowtoredrawthe

contentsofitswindow

OCOMPUTEROPERATINGSYSTEMS

OPERATINGSYSTEMFEATURES

Windows32-bitoperatingsystem,GUI,multitasking,

98&95networking

WindowsNT,32-bitoperatingsystemnotlimitedtoIntelchips.

Me&2000&Multitasking,multiprocessing,networking

XP,2003

WindowsCEPaired-downforhandheldcomputers,wireless

communicationdevices

OS/232-bit.DevelopedforIBMPS/2.Multitasking,

networking

ICROCOMPUTEROPERATINGSYSTEMS

OPERATINGSYSTEMFEATURES

UnixForpowerfulmicrocomputers,workstations,

minicomputers.Multitasking,multi-user

processing,networking.Portabletovarious

computerplatforms

LinuxFree,reliablealternativetoUnix,Windows.

RunsonmanyPlatforms.Open-source

MacOSForMacintoshcomputers.Multitasking.

Powerfulgraphics,multimedia

DOSForIBM(PC-DOS)andPC(MS-DOS).

Programmemory:640K

SelectinganOperating

System

•IsourexistingsoftwarecompatiblewiththeOS?

•DoestheOShavealargebaseofcompatible

software?

•HowreliableistheOS?Doesitcrashfrequently?

•IstheOSavailableforawidevarietyofhardware?

•Howquicklydoesitrun?

•Howeasyitistolearnanduse?

•Howeasyisittoinstallandconfigure?

•Howmuchdoesitcost?

APPLICATIONSOFTWARE

Generalizedprogramsthat

SYSTEMSOFTWAREmanagetheresourcesof

thecomputer,including

-OperatingSystem:

HARDWARE

•Scheduledcomputerevent

•Allocatescomputer

resources

•Monitorsevents

-Languagetranslators:

•Interpreters

•Compilers

-UtilityPrograms:

•Routineoperations

•Manage

Programswrittenforaspecificapplicationtoperformfunctions

specifiedbyendusers.

-ProgrammingLanguage

EXAMPLE:7+10=?

MachineLanguage

AssemblylanguageInstructionProgram:

Program:00111110操作码(LDA)

LDA,700000111操作数(7)

ADDAJO11000110操作码(ADDA)

HALT00001010操作数(10)

01110110操作码(HALT)

^^INSTRUCTION&EXECUTIONCYCLE

Address

00000000

00000001

00000010

00000011

00000100

TRANSLATIONPROCESS

SOURCECODE

PROGRAMHigh-levellanguageinstructions

COMPILERTranslateshigh-levelcodeintomachinelanguage

UTILITYPROGRAMS

OBJECTCODEReadyfbrcomputer

LINKAGEOTHEROBJECT

EDITORCODEMODULES

LOADMODULE

GENERATIONSOF

PROGRAMMINGLANGUAGES

1st.Since1940s.MACHINELANGUAGE:

binarycode

2nd.Sinceearly'50s.ASSEMBLY

LANGUAGE:

mnemonicsfornumericcode

3rd.Sincemidc50s.HIGH-LEVEL

LANGUAGES

4th.Sincelate'70s.

APPLICATIONSOFTWARE

Generalizedprogramsthat

SYSTEMSOFTWAREmanagetheresourcesof

thecomputer,including

-OperatingSystem:

HARDWARE

•Scheduledcomputerevent

•Allocatescomputer

resources

•Monitorsevents

-Languagetranslators:

•Interpreters

•Compilers

-UtilityPrograms:

•Routineoperations

•Managedata

Programswrittenforaspecificapplicationtoperformfunctions

specifiedbyendusers.

-ProgrammingLanguage

-softwarepackage

UtilityPrograms

•Routineoperations

-Eg.,Sort,list,print,

•Managedata

-Eg.,createfile,mergefile,

▼ApplicationSoftwareand

ProgrammingLanguages

•Programminglanguages:

-evolvedfrommachinelanguagetohigh-level

languagesforbusinessandscientificwork

•Importantprogramminglanguagesfor

businesstoday:COBOL,C,C++,and

VisualBasic,soon

际

ProgrammingLanguages

cOperatingsystems;applicationsoftware

C++Object-oriented;applicationsoftware

COBOLBusinessadministration;alphanumeric

processing

VisualBasicVisualtool;Windowsapplications

FORTRANProcessingnumericdata;scientific,

engineeringprograms

BASICUsedfbrteaching

PascalUsedprimarilyfbrteachingprogramming

Fourth-GenerationLanguages

•Fourth-generationlanguage:

-Canhelpendusersdevelopsoftwarewithlittle

ornoassistancefromISspecialists,less

procedural

-6CATEGORIES

•Naturallanguages:

-Closetohumanlanguage

OURTHGENERATIONLANGUAGES

(4GL)

QueryVeryhigh-level

Application

language/GraphicProgramming

generators

Reportlanguagelanguage

generators

egSQLSASGraphPowerBuilderGPSS

gRPG-III

SystatMicrosoftFrontPageAPL

Nomad2

Application

softwarePCtools

package

SAPR/3Lotus1-2-3

InternetExplore

Access

,^BONTEMPORARYTOOLSFOR

SOFTWAREDEVELOPMENT

•Object-orientedprogramming

-Approachtosoftwaredevelopmentthat

combinesdataandproceduresintoasingle

object

•Objectsareindependent,reusablebuildingblocks

•Basedonconceptsofclassandinheritance

•Visualprogramming

-Constructionofsoftwareprogramsbyselecting

andarrangingprogrammingobjects

Classandinheritance

,^CONTEMPORARYTOOLSFOR

SOFTWAREDEVELOPMENT

•Java

-Object-orientedProgramminglanguage,

-Deliversthesoftwarefunctionalityneededfbraparticulartask

-Runsonanycomputerandoperatingsystem,Platform-independent

•HypertextMarkupLanguage(HTML):

-Pagedescriptionlanguage,createsWebpagesandother

hypermediadocuments

•XML(extensibleMarkupLanguage):

-Describesthestructureofadocument,supportslinkstomultiple

documents,allowingdata

ApplicationSoftwarePackages

一andProductivitySoftware

•PCsoftwaretools:

-Wordprocessingsoftware:Create,format,printdocuments

-Desktoppublishingsoftware:Produceprofessional-qualitydocuments

withgreaterformatting,designcapabilities

-Spreadsheets:Displaydataingridfbrrecalculatingnumericaldata

-Datamanagementsoftware:Store,manipulatedatainlistsand

databases

-Presentationgraphics:Createprofessional-qualitygraphicsand

multimediapresentations

-IntegratedSoftwarePackagesandSuites:Combinetwoormore

applications;easydatatransfer

•Otherproductivitysoftware:

-E-mailsoftware:Computerexchangeofmessages

-Webbrowsers:AccessanddisplayWeb,Internetresources

-Groupware:Supportactivitiesofworkgroups

^^|oftwarePackageforEnterprise

Integration

•Enterprise(business)software

-Eg.，ERP,SCM,CRM,

-Setofintegratedmodulesformajorbusiness

functions

-Allowsdatatobeusedbymultiplefunctions

andbusinessprocesses

•Legacysystem:

-Systeminplaceforlongtime

SELECTEDEXAMPLESOFAPPLICATION

SoftwarePackages

ENTERPRISERESOURCEPLANNING;MATERIAL

REQUIREMENTPLANNING;MNAUFACTURINGRESOURCE

PLANNING;E-COMMERCE,CUSTOMERRELATIONSIP

MANAGEMENT;BUSINESSINTELLIGENCE;ACCOUNTS

PAYABLE/RECEIVABLE;ARCHITECTURALDESIGN;

BANKING;SUPPLYCHAINMANAGEMENT;COMPUTER-

AIDED-DESIGN;DOCUMENTIMAGING;TRAVELAGENCY;E-

MAIL;FINANCIALCONTROL;FORECASTING;FORMS

DESIGN;GRAPHICS;HOTELMANAGEMENT;HUMAN

RESOURCES;INSTALLMENTLOANS;INVENTORYCONTROL;

JOBCOSTING/SCHEDULING;LIFEINSURANCE;HOTEL

MANAGEMENTSYSTEM;MATHEMATICAL/STATISTICAL

MODELING;ORDERENTRY;PAYROLL;PROCESSCONTROL;

REALESTATEMANAGEMENT;SALES&DISTRIBUTION;

■SAVINGSSYSTEMS;STOCKMANAGEMENT;TAX

ACCOUNTING;UTILITYCONTROLS;WORDPROCESSING

*

到SoftwareforEnterprise

Integration

•Middleware

-Allowstwodisparateapplicationstocommunicateto

exchangedata

ApplicationData,MiddleData.Application

ACommandswareCommandsB

•Enterpriseapplicationintegration(EAI)software

-Tiestogethermultipleapplicationstosupportenterprise

integration

Enterpriseapplicationintegration

(EAI)softwareversustraditional

integration

SoftwarefbrEnterpriseIntegration

Webservices:

-UniversalstandardsusingInternettechnologyfbr

exchangingdatabetweensystems

Webserver:

-ManagesrequestsfbrWebpagesoncomputerwhere

theyarestored

Applicationserver:

-Middlewaresoftwarehandlingapplicationoperations

betweenuserandback-endbusinesssystems

lumtiereaarcmtecturetore-

commerceande-business

Sales

InternetProduction

Accounting

HR

ClientWebApplication

ServerServer

Back-End

Systems&Data

软件的发展趋势

•硬件和软件的发展是不对称的。

­硬件是以等比的速度增长

-（每1.5年增长一倍），

­而软件是等差级数增长

-（每年增长4-7%）.

w软件危机

・“软件危机”在六十年代已经存在

-一些过来人把软件人员形容为“陷入泥潭中的一群野兽”

-七十年代后期愈演愈烈:根据美国政府统计局1979年公布的统计数

字表明，几个联邦软件计划共投资6.8百万美元，47%($3.2M)交

付但从来未使用，29%($2.0M)投资了但未交付，19%($1.3M)被

费弃或返工，3%(0.2M)经过某种改变后被使用，仅2%(0.1M)交付

后被使用。

•90年代，软件危机尚未过去

-如Widows2000的发行，根据微软一份备忘录显示：微软共

发现63000个“潜在问题”，可能影响Windows2000的运行

•逾21000“延迟性”设计缺陷，其中相当多部分被微软公司认定

为“真正的问题”，

・逾27000条“Bug”，在微软看来，这代表“尚未完成的工作”

或“久被遗忘的问题”。

-实力最强大的软件公司尚如此，何况其他软件产

品呢？

SoftwareTrends

•使用更方便

­与人的交流方法更广泛

•软件的集成性增加

・自然语言，多目标，图形接口，专家辅

助

•OpenSourceDevelopment

OpenSourceDevelopment

•Thereisanincreasingtrendtowardusing

thisasamethodofsoftwaredevelopment.

•Inthismethodsourcecodeisdistributed

anddeveloperscanimproveandaddtocode

astheyseefit,goodideasarethenincluded

intotheproduct.

•Thismethodallowssoftwareproductsto

growandimproveinanaturalorganicway.

Movingyourcompanyfrom

productstoservices

•Supportingthesoftware

•Improvingthesoftware

•Integratingthesoftware

•Problemswithopensource

-anybody,nobodyresponsible

CostofOwnership(TCO)of

TechnologyAssets

•Includesbothdirectandindirectcosts

•Hardwareandsoftwareac