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TABLE OF CONTENTS

1. Information Systems...........................................................................31.1 What is a System................................................................................................3

1.2 What is an Information System?.................................................32. Systems Analysis Intro!"#tion......................................................$ 2.1 What is Systems Analysis % &esi'n?...........................................$3. S(STE)S ANAL(SIS...........................................................................$

3.1 S(STE) &E*ELO+)ENT LIFE C(CLE ,S&LC-..............................................$ 3.1.1 Com "ter Assistant Soft/are En'ineerin' ,CASE-......................................0 3.1.2 sers...................................................................................................................3.2 &esi'n y rototy in'.....................................................................................113.3 S(STE)S IN*ESTI4ATION.............................................................................13

$. +ro#ess )o!elin'..............................................................................156. Systems &esi'n.................................................................................217. In "t8O"t "t &esi'n an! "ser interfa#es........................................265. TESTIN4 an! &EB 44IN4..............................................................33 5.1 TESTIN4...........................................................................................33 5.2 &e "''in'........................................................................................3$ 5.3 Installation Inte'ration..................................................................37

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1. Information Systems

1.1 What is a System A system is a set of components that interact to accomplish some purpose. e.g. College

system, Economic system, Language system, a Business and its parts - Marketing, Sales,Research, Shipping, Accounting, o!ernment.

1.2 What is an Information System?

Information System ,I.S.- " #nterrelated components $orking together to collect,process, store, and disseminate information to support decision making, coordinationcontrol analysis and !isuali%ation in an organi%ation.

Information9 &ata that ha!e 'een shaped into a form that is meaningful and useful tohuman 'eings.

&ata9 Streams of ra$ facts representing e!ents occurring in organi%ations.

In "t9 (he capture or collection of ra$ data from $ithin the organi%ation or from itse)ternal en!ironment. +ro#essin'9 (he con!ersion, manipulation, and analysis of ra$ input into a form that ismore meaningful to humans.

O"t "t9 (he distri'ution of processed information to the people or acti!ities $here it $ill'e used.

Fee! a#:9 *utput that is returned to the appropriate mem'ers of the organi%ation tohelp them e!aluate or correct the input.

Com "ter Base! I.S. ,CBIS-9 #.S. that rely on computer hard$are and soft$are for processing and disseminating information.

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InputProcessing

ClassifyArrange

Calculate

Output

ORGANIZATION

FEE !AC"

INFORMATION SYSTEM


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2. Systems Analysis Intro!"#tion

2.1 What is Systems Analysis % &esi'n?(he process of e)amining a +'usiness situation $ith the intent of impro!ing it through 'etter

procedures and methods.System Analysis - rocess of gathering and interpreting facts, diagnosing pro'lems, andusing the facts to impro!e the system.

Systems &esi'n - rocess of planning a ne$ system to replace or complement the old. Analysis specifies what the system should do and design states how to achie!e theo' ecti!e.Note " (his e)amination should al$ays 'e initiated 'y the people in!ol!ed in the situation+or $ho $ill 'e in!ol!ed in a ne$ situation . #t is the o' of the analyst to suggest solutions,'ut not make 'usiness decisions. +A computer 'ased solution is not necessarily the only

one/ .

What Systems Analysis is NOTStudying a 'usiness to decide $hich e)isting procedures should 'e handled 'y thecomputer and $hich should 'e done 'y non-computer methods.

• &etermining $hat changes should 'e made.• #nitiate ne$ procedures and practices.

3. S(STE)S ANAL(SISO+O;T NIT( TO I)+;O*E A S(STE)

3.1 S(STE) &E*ELO+)ENT LIFE C(CLE ,S&LC- A System !e


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S2. System Analysisriori%ation of the re3uirements for sol!ing the pro'lem. (he emphasis is on the

'usiness, not the computer.#n other $ords, is the study of current 'usiness and information system, and the

definition of user re3uirements and priorities for ne$ information system.Synonyms include 'usiness pro'lem analysis, re3uirement analysis, and logicaldesign.Basically, W=AT TO &O> NOT =OW TO &O IT.

What sho"l! system !o?- keep records of sales- keep records of stock le!els - produce sales reports

Feasi ility St"!y Ad!antages 4s &isad!antage

T Te#hni#al feasi ility +technically practical, staff, e)pertiseE E#onomi# feasi ility

#s it cost effecti!e2L La/ feasi ility

#s it legal2O O erational feasi ility

&oes it fulfil user re3uirements2(o $hat degree21ill the $ork en!ironment change25o$ does users feel a'out such a solution2

S S#he!"le feasi ility&esign and implementation in accepta'le period of time2

S3. System &esi'n(he e!aluation of alternati!e pro'lem solutions and the detailed specifications of the final solution computer-'ased. Emphasis shifts from the 'usiness to thecomputer solution.Sent to programmers.#t is also called physical design.Basically, =OW TO &O IT.

Lo'i#al• 1hat data to hold2• 1hich process to transform data2

+hysi#al• 1hich soft$are and hard$are to use2• &ecided on a package $hich could 'e modified

S$. System Im lementation(he construction or assem'ly of the ne$ system and the deli!ery of that system

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into 6production7 +meaning 6day-to-day operation7 .

Buy and install hard$are• #nstall soft$are• Set up data files• 8(est Run8 system• 8 o li!e8

S6. System S" ort % )aintenan#e(he ongoing maintenance and enhancement of a system after it has 'een placedinto operation. (his includes program maintenance and system impro!ements.

• Enhancements to soft$are• to produce reports on certain items only 6group8 items and sort into

!arious orders for reports.

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3.1 ,Contin"e!- Systems &e


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implement other soft$are+s +similar to the CA& technology for engineers .

ro ect Management tools and (echni3ues

ER( C5AR( + ro ect E!aluation and Re!ie$ (echni3ue A graphical net$ork model used to depict the interdependencies 'et$een pro ect tasks.

E@am le " A ER( Chart diagram for the Analysis phase of a system pro ect

LABEL

ACTI*IT( +;E&ECESSO; & ;ATION

A Conduct #nter!ie$s ?one ;B Administer @uestionaires A <C Collect Company Reports ?one <& Analy%e &ata :lo$ B,C

E #ntroduce rototype B,C 0: *'ser!e Reactions to rototype E ;

erform Cost Benefit Analysis & 95 repare roposal 9# resent roposal 5 9

Ta le 3.19 Acti!ities of the Analysis phase

Fi'"re 3.29 ER( Chart for the analysis phase

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antt Chart A simple time-charting tool used for pro ect scheduling and progress e!aluation. A 'ar chartto depict pro ect tasks against a calendar.

E@am le "

Fi'"re 3.39 antt Chart for the System &e!elopment.

3.1.2 sers&ire#t

• interact $ith the system direct• initiate Administrati!e - Money• Actually interact $ith the system. (hey feed in data or recei!e output,

possi'ly using a terminal. A ne$ system $ill considera'ly change the daily$ork of these users.

In!ire#t sersBenefit from the results of reports produced 'y the Computer System. (heseusers may 'e managers of 'usiness functions using the system.

A!ministrati


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Systems Analysts - E!erything(hey com'ine the responsi'ilities of B.A. and S.&.

Analyst +ro'rammers - E!erything +or $hat they kno$Com'ine responsi'ilities of S.A. and rogrammers, i.e. they also de!elop the soft$are to

implement the design.

What !oes a Systems Analyst !o?• Conduct a study of the feasi'ility of the proposed system.• Liaise $ith users of the system and determine their re3uirements.• :ind out the facts rele!ant to the design of the proposed system.• &etermine the human and computer procedures that $ill make up the system,

designing forms, files, reports.• 1rite program specifications.• (est the programs and the system.• articipate in the implementation of the system.• &ocument the system.• &o anything else that $ill produce an efficient and effecti!e system.

What s:ills !oes a system analyst nee!?• (he a'ility to communicate !er'ally and in $riting.• (o e)tract rele!ant facts - a &etecti!e.• (o o'tain information in a reasona'le $ay - a &iplomat.• (o interpret a um'le of facts and con!ert them into a logical form.• (o understand and ha!e a 'road kno$ledge of modern computer hard$are

soft$are.• (o keep up-to-date on System Methodologies.• (o 'e creati!e.

S.A. Characteristics" trusted, de!elop ideas in an o' ecti!e $ay, range of social skills,patient, percepti!e, fair, un'iased, persistent, good listener, empathy.

"estions

F. 5o$ $ould you define an 8effecti!e system82

9. 1ould a system produced 'y analyst programmers 'e more or less 8effecti!e8than one produced 'y separate people2

;. sers ha!e a right to influence systems design. &o you agree $ith this2


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+eo le in


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So, a simple prototype designed to accommodate 'road needs, together $ith possi'ilitiessuggested 'y the designer using e)perience gained in other pro ects may 'e used todefine re3uirements more accurately.

+rototy e

#t is a li!e $orking system not ust a paper 'ased. sers can test its operation ande)plore its facilities and so do not ha!e to rely upon $ritten descriptions. #t is an iterati!eprocess.

The rototy e a roa#h

Analyst(he prototype approach ser

SE; ANAL(ST

"estionsF. *utline a comparison 'et$een the t$o approaches of designing a system that is the

system life cycle and the prototype.

9. #dentify the negati!e and positi!e aspects of each one of them2 1hich one $ouldyou use and $hy2

Ad!antages D disad!antages

(echnology Strategy of prototyping

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#dentifies 'asicinformation

re3uirements Analystde!elops

system thatfullfil 'asic

re3uirements

E)periments$ith

'asic system inactual

application

Analyst refinesprototypesystem to reflect

identifiedre3uirements


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3.3 S(STE)S IN*ESTI4ATION

1. Inter


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=. 5o$ often is it done2J. 1ho uses the resulting information2

. 1hat data is used and or produced during the process2 Ask to see 8records8.K. 1hat are the limits imposed 'y time and the !olume of $ork2 1hat 8triggers8 the

acti!ity2 1hen does this happen2 1hen must it 'e completed2 5o$ often does it

happen +!olumes 2F .1hat performance controls are used2FF. Are there specific performance standards2 1ho compares performance against

standards2 5o$ are mistakes caught and the errors handled2 Are the errorse)cessi!e2

=o/ to Con!"#t a S"##essf"l Inter


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$. O ser


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A system made 'y Analyst programmers is more effecti!e than one made 'y separatepeople 'ecause the analyst $ill analy%e the program ha!ing in mind all the pro'lems andhe $ill not ha!e to e)plain e!erything to other person. But if separate people analy%ethe system and program then they $ill ha!e to e)plain e!erything to different people.

3. W=IC= DOB IS T=E )OST SATISF(IN4> S(STE)S ANAL(ST O; ANAL(ST+;O4;A))E; O; +;O4;A))E;?(o 'e a programmer is the most satisfying o' +for most computer science persons 'ecauseyou do not depend on anyone else to do your o'. >ou only need the analyst to e)plain toyou $hat he $ants out of the program.

$. SE;S =A*E T=E ;I4=T TO INFL ENSE S(STE)S &ESI4N. &O (O A4;EE WIT=T=IS?# 'elie!e they +must ha!e the right +and the responsi'ility to influence systemsdesigns 'ecause they are the ones $ho kno$ $hat their company really needs+re3uirments . (he users do not kno$ e)actly $hat kind of a program might 'e usefulfor each purpose and $hat a program needs in order to get the most out of it.

6. E +LAIN T=E S&LC AN & &ESC;IBE EAC= OF T=IS IN*OL*E& IN IT?S&LC are the steps used for system analysis and design $hich are" Q

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$. +ro#ess )o!elin' A techni3ue used to organi%e and document the systemPs processes.

&e#om osition &ia'ram % &ata Flo/ &ia'rams ,&.F.&.s-&e#om osition &ia'ram

A tool used to depict the 'reaking of a system into su'components.

Fi'"re $9 art of the &ecomposition diagram of :#( &4& clu'.

&ata Flo/ &ia'ram ,&F&- sho$ ho$ data flo$s around an information system.(hey are a simple and po$erful graphic techni3ue $hich is 'oth easily updated and easilyunderstood 'y users. (his is 'asically one of the main diagrammatic techni3ues of SSA&M+Structured System Analysis and &esign Methodology . SSA&M is e)plained in Appendi) A.

+ro#ess9 Sho$s a transformation of data and is also referred to as a function.n is the num'er of the process, this num'er also indicates the le!el of the process.

? is the process name.

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&ata Flo/ hysical :lo$ of data&:?ame" &ata :lo$ ?ame

EN" #s the e)ternal entity nameE@ternal entity +source and or sink of information D destination. (his can 'e a person,orani%ational unit, system or another orgni%ation interacting $ith the system. Also, callede)ternal agent.

&ata Store " Storage of &ata&Sn - &ata Store n +num'er&S?ame - &ata Store name

;"les ,all of the follo/in' are not ermitte!-

Miracle

Black 5ole

+ &. S. E.E

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&S?ame

&:?ame


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+ &. S. G GE.E G G

lus, additionally,Each data store must ha!e at least one input flo$ and one output flo$ +read $rite .

4ray =ole " #nsufficient input

What is a &F&?

A hierarchical set of diagrams $hich is used to define"

- the 'oundary of the system to 'e de!eloped- the information flo$ to and from the system- data flo$s $ithin the system- the functions used 'y the system.

+used to define the pro ect scope and to pro!ide measures of performance - for use inestimating and planning .

=o/ is it !e


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O e#t mo!ellin'#s a techni3ue $hich identifies o' ects and their relationships $ithin a the system.

nifie! )o!elin' Lan'"a'e , )L-2 $

An approach that utili%es o' ect modelling languages.

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6. Systems &esi'n(he e!aluation of alternati!e solutions and the specification of a detailed computer 'ased solution. Also called physical design. &ri!en 'y system designers and or systemanalysts.

&esi'n System analysis +re3uirementsSystem design deals $ith the physical or implementation dependentaspects of a system +the systemPs technical specifications =OW TO.

Systems design 'uilds on the kno$ledge deri!ed from systems planning and systemsanalysis.

urchase soft$are 4s &e!elop soft$are +$hy rein!ent the $heel .Buy soft$are packages D to fulfil end user re3uirements.

System Analyst rimarily focused on the logical, implementationindependent aspects of the system +re3uirements .

System !esi'n&eals $ith the physical or implementation

dependent aspects of a system +systemPs technical specifications .

⇒ &esi'n ro#ess3 hases of System &esi'n

a' Sele#tion +hase - E!aluation and selection of alternati!e solutions -' A# "isition +hase - Ac3uisition or purchase of computer soft$are and hard$arec' &esi'n % Inte'ration +hase - (raditional physical design and integration of

computer-'ased components

A. Sele#tion +hase Acti!ities or Steps

1. S e#ify alternati


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:ulfil user re3uirements21hat degree21ork en!ironment change25o$ does users feel a'out such a solution

9.; Economic feasi'ilityCost effecti!e2

9.< Schedule feasi'ility&esign and implementation in accepta'le period of time2

3. ;e#ommen! a sol"tion

#nfeasi'le candidate eliminated

Candidate that offers the 'est o!erall com'ination

⇒ System roposal +for system o$ner for final decision

ro ect plansSi%e estimatesCandidate solutions:easi'ility analysis

B. A# "isition hase an! system !esi'nStep or Acti!ity

F. ;esear#h Te#hni#al #riteria an! o tionsResearch technical alternati!es hard$are and or soft$are re3uirements

roduct and random facts from !arious sources#nternal standards may e)ist for hard$are and soft$are selection.#nformation ser!ices +sur!ey the marketplace for ne$ products .(rade ne$spapers and periodicals.

2' Soli#it +ro osals ,or "otes- from *en!ors

Baying from a single source 4s use the competiti!e marketplaceRe3uest for 3uotation +R:*Re3uest for roposal +R:

3. *ali!ate *en!or #laims an! erforman#e

$. E


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contractagreement

7. Esta lish Inte'ration ;e "irements#ntegrate or interface the ne$ system to the e)isting systems

ro'lems" different technologytechni3uesstructures

C. Esta lish Inte'ration ;e "irements

&e!eloping technical design specifications

• &esign and #ntegration hase

eneral &esign &etailed &esign*utline of the o!erall &e!eloping the detail design&esign specifications for

components in the outline.

1- Analyse an! &istri "te !ata

&ata model e)ist de!elopment of ideal file and data'ase solutions&ata analysis " A procedure that prepares a data model for implementation as a no

redundant fle)i'le, and adapta'le file data'ase.

NormaliJation9 (he procedure that is used to simplify entities, eliminate redundancyand 'uild fle)i'ility and adapta'ility into a data model. &ata attri'utes aregrouped together D sta'le, fle)i'le

E


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6- &esi'n Com "ter O"t "ts an! In "ts#nput and *utput design re3uirementsEnd-users -ideas, suggestions, especially regarding format.

7- &esi'n On line "ser interfa#e&ialogue 'et$een the end-user and computer easy to learn and easy to use dialogue.

5- +resent an! ;e +ilot> +arallel

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7. In "t8O"t "t &esi'n an! "ser interfa#es

&ata Entry )etho!s an! &e


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printed on an original document at the time of it 'eing created. (he characters areprinted using magnetic ink. (he !alue is that the characters are reada'le 'y humans and'y machines. (he only common use for such characters is the data printed on the'ottom of che3ues containing account identification.

(he 'ig ad!antage of 'oth *CR and *MR is that data can 'e input to a computer system $ithout ha!ing to 'e transcri'ed first, there'y cutting do$n the num'er of errorson data input '

(he real ad!ances in keyless data entry are coming for on-line systems. Bar #o!in'systems +similar to uni!ersal product code systems that are commonplace in the groceryand retail industries are $idely a!aila'le for many modern applications. :or e)ample,:ederal E)press creates a 'ar code-'ased la'el for all packages $hen you take thepackage to a centre for deli!ery. (he 'ar codes can 'e read and traced as the packagemo!es across the country to its final destination.

Bar#o!e rea!ers. A 'arcode reader is a laser scanner that reads the reflected laser light from a series of dark and light coloured lines of !arying thickness. (he different$idths of pairs of lines make up a code that can 'e con!erted into a num'er. (hisnum'er can then 'e used as the keyfield relating to a file of items that ha!e 'een'arcoded. (he details of the contents of the 'arcodes are not of importance to us in thissection, e)cept to say that 'arcodes can easily 'e misread 'y the system, so one of thedigits in the num'er is used to check that the rest of the code has 'een read properly.(his digit is called the check digit, and $ill 'e discussed in more detail later in thecourse. Barcodes are particularly useful 'ecause they do not rely on human 'eings toinput the data, although, if the 'arcode is damaged so that the laser scanner cannotread it properly, the digits represented 'y the code are printed underneath so that theycan 'e input 'y a user at a key'oard. Barcodes are used $here the data does notchange, and so can 'e printed on original packaging.

Geyless data entry should 'e considered for appropriate high-!olume transaction-'asedsystems as they 'ecome candidates for redesign.

Pen Input en-'ased computing is starting to e!ol!e. As pen-'ased operating systems +e.g.,

MicrosoftHs en 1indo$s 'ecome more $idely used and tools for 'uilding pen-'asedapplications 'ecome a!aila'le, $e e)pect to see more system designs that e)ploit thistechnology. Some 'usinesses already use this technology for remote data collection. :or e)ample, S uses pen-'ased note'ook systems to communicate deli!eries to dri!ersand to collect deli!ery confirmation signatures and data from customers and dri!ers.1hen a dri!er returns to their distri'ution centre, the data is transmitted from thepen-'ased note'ook computer to host computers.

S#anners . A scanner is a de!ice that con!erts a document into a series of pi)els +pictureelements D these are small s3uares that, $hen put together, form a picture . (he larger the num'er of pi)els, or con!ersely the smaller each indi!idual pi)el, the 'etter thedefinition of the final picture. (here are different types of scanner, 'ut all use the sameprinciple to create the image. A typical use for a scanner $ould 'e to input a picture of a

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house so that it could 'e included $ith the details of a house that is for sale in an estateagentPs pu'lication.

4ra hi#s Ta let . A graphics ta'let is a flat surface on $hich a piece of paper is placed.(he user can then dra$ on the paper and the ta'let $ill sense $here the pencil is

pointing and transfer the line to the screen.

)i#ro hones . sed to input sound to a computer system.

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$ith the other types 'ut used $here it is necessary to gi!e a good impression, for instance sending letters from a solicitorPs office to clients.

lotters are a type of printer designed for dra$ing lines and geometric designs rather than for producing characters. (he image is created 'y pens 'eing mo!ed across apiece of paper, under the command of the processor. lotters tend to 'e used for

dra$ing 'lueprints, perhaps in an architectPs office to produce detailed dra$ings of 'uildings for 'uilders to follo$.

S ea:ers . sed to output sound from a computer system.

(here are many other peripheral de!ices and, as has 'een mentioned, kno$ledge of some others $ill not come amiss, ho$e!er that is enough to 'e a'le to ans$er 3uestionsin the e)am. (he 3uestions $ill normally take the form of presenting a scenario and thenasking for a description of the hard$are re3uired. (he important thing to remem'er isho$ the marks $ill 'e a$arded. (here $ill not 'e a mark for e!ery de!ice mentioned, 'utthe candidate $ill 'e e)pected to gi!e sensi'le suggestions for each of the four areas of peripherals mentioned at the start of this section. #n other $ords the mark $ill not 'e for a key'oard or a mouse, 'ut for suggesting sensi'le methods of input to the system.

4ra hi#al "ser interfa#es

raphical user interfaces are a method of user communication $ith an operatingsystem. (hrough the interface, the user gi!es the operating system commands. 1ith agraphical user interface, rather than typing commands, the user $ill select icons,'uttons, 'ars or 'o)es to perform a task. sually a mouse is used to make the selection.Many people 'elie!e that graphical user interfaces are 3uick and easy to learn, promotestandardi%ation of application program interfaces and reduce errors.

4ra hi#al "ser interfa#es ,4 Is- $ere populari%ed 'y the success of AppleHsMacintosh and MicrosoftHs 1indo$s. 1hile the commercial success has 'een dri!en 'yapplications such as $ord processing and spreadsheets, the popularity of the interfaceis dri!ing all applications to the interface.

(echnology e)ists to create #-like applications for dum' terminals. (echnology alsoe)ists to create true C-'ased #s that $ork $ith host applications !ia cooperati!eprocessing. And most importantly, # technology has 'ecome the user interface of choice for client ser!er applications.

#s do not automatically make an application 'etter. oorly designed #s can negatethe alleged ad!antages of consistent user interfaces. :ortunately, # standards aree!ol!ing to guide system designers to create consistent interfaces. :or e)ample,&*S 1indo$s and *S 9 resentation Manager are 'ased on a standard calledCommon User Access (CUA). roperly designed #s simplify input, reduce keystrokesre3uired, and pro!ide interesting and useful formatting options for outputs. Many'usinesses are mandating their use for all ne$ systems.

System ser Iss"es for In "t an! O"t "t &esi'n

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Because inputs originate $ith system users and outputs are used 'y system users,human factors play a significant role in 'oth input and output design. inputs should 'e assimple as possi'le and designed to reduce the possi'ility of incorrect data 'eingentered. System users must find computer outputs easy to use and helpful to their o's.:urthermore, if 'atch input methods are used, the needs of data entry clerks must also

'e considered. 1ith this in mind, se!eral human factors should 'e e!aluated.

First> the !olume of data to 'e input should 'e minimi%ed. (he more data that is input,the greater the potential num'er of input errors and the longer it takes to input that data.(hese general principles should 'e follo$ed for input design"

• Enter only variable data. Do not enter constant data. For instance, when deciding what elements to include in a A!E "#DE# in$ut, we need %A#& 'U E#s *or all

$arts ordered. +owever, do we need to in$ut %A#& DE C# %& "'s *or those $arts-%A#& DE C# %& "' is $robably stored in a com$uter *ile. i* we in$ut %A#& 'U E#, we can loo u$ %A#& DE C# %& "'. %ermanent (or semi/$ermanent)data should be stored in *iles. "* course, in$uts must be designed *or maintaining those *iles.

• Do not in$ut data that can be calculated or stored in com$uter $rograms. :or e)ample, if you input @ A?(#(> *R&ERE& and R#CE, you donHt need to inputE (E?&E& R#CE, $hich is e3ual to @ A?(#(> *R&ERE& R#CE. Another e)ample is incorporating :E&ERAL (A 1#(55*L? data in ta'les +arraysinstead of keying in that data e!ery time.

. Use codes *or a$$ro$riate attributes. Codes $ere introduced earlier. Codes can 'etranslated in computer programs 'y using ta'les.

Se#on! , source documents should 'e easy for system users to complete. (he follo$ingsuggestions may help"

. nclude instructions *or com$leting the *orm. Also, remem'er that people donHt like toha!e to read instructions printed on the 'ack side of a form.

. inimi0e the amount o* handwriting. Many people suffer from poor penmanship. (hedata entry clerk or CR( operator may misread the data and input incorrect data. secheck 'o)es $here!er possi'le so the system user only needs to check the

appropriate !alues.

Thir!> design documents so that they can 'e easily and 3uickly entered into the system.1e suggest the follo$ing"

. Data to be entered ( eyed) should be se1uenced so it can be read li e this boo , to$to bottom and le*t to right +see :igure F=A . (he data entry clerk should not ha!e tomo!e from right to left on a line or ump around on the form +see :igure F=AB to finddata items to 'e entered.

. deally, $ortions o* the *orm that are not to be in$ut are $laced in or about the lower

right $ortion o* the source document +the last portion encountered $hen reading top

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to 'ottom and left to right . Alternati!ely, this information can 'e placed on the 'ack of the form.

(hese are only guidelines. System users should ha!e the final say on source documentdesign/ Many of these same system user issues also apply to output design. (he

follo$ing general principles are important for output design"

2. Com$uter out$uts should be sim$le to read and inter$ret. (hese guidelines mayenhance reada'ility"

. E!ery report or output screen should ha!e a title.

. Reports and screens should include section headings to segment large amountsof information.

. #nformation in columns should ha!e column headings.

. Because section headings and column headings are fre3uently a''re!iated toconser!e space, reports should include legends to interpret those headings.

. Legends should also 'e used to formally define all fields on a report. >ou ne!er kno$ $hose hands a report might end up in/ ('ote3 Legends can 'e 'uilt intoon-line outputs using function keys to temporarily interrupt the output to displaylegends and help.

. Computer argon and error messages should 'e omitted from all outputs.

*n many computer outputs, these guidelines are ignored or o!erlookedIconse3uently, the outputs appear cluttered and disorgani%ed.

4. &he timing o* com$uter out$uts is im$ortant. *utputs must 'e recei!ed 'y their recipients $hile the information is pertinent to transactions or decisions. (his canaffect ho$ the output is designed and implemented.

5. &he distribution o* com$uter out$uts must be su**icient to assist all relevant systemusers.

6. &he com$uter out$uts must be acce$table to the system users who will receivethem. An output design may contain the re3uired information and still not 'eaccepta'le to the system user. (o a!oid this pro'lem, the systems analyst mustunderstand ho$ the recipient plans to use the output.

Internal Controls for In "ts an! O"t "ts#nternal controls, a continuing theme throughout the design chapters of this 'ook, are are3uirement in all computer-'ased systems. #nput controls ensure that the data input tothe computer is accurate and that the system is protected against accidental andintentional errors and a'use, including fraud. *utput controls ensure the relia'ility anddistri'ution of the outputs generated 'y the computer. (he follo$ing internal controlguidelines are offered for inputs"

2. The number of inputs should be monitored. (his is especially true $ith the 'atchmethod, 'ecause source documents may 'e misplaced, lost, or skipped.

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. #n 'atch systems, data a'out each 'atch should 'e recorded on a 'atch control slip.&ata includes BA(C5 ? MBER, ? MBER *: &*C ME?(S, and C*?(R*L(*(ALS +e.g., total num'er of line items on the documents . (hese totals can 'ecompared $ith the output totals on a report after processing has 'een completed. if the totals are not e3ual, the cause of the discrepancy must 'e determined.

. #n 'atch systems, an alternati!e control $ould 'e one-for-one checks. Each sourcedocument $ould 'e matched against the corresponding historical report detail linethat confirms that the document has 'een processed. (his control check may only 'enecessary $hen the 'atch control totals donHt match.

. #n on-line systems, each input transaction should 'e logged to a separate audit fileso it can 'e reco!ered and reprocessed in the e!ent of a processing error or if data islost.

4. Care must also be taken to ensure that the data is valid . &wo types of errors caninfiltrate the data" data entry errors and in!alid data recorded 'y system users. &ataentry errors include copying errors, transpositions +typing F;9 as F9; , and slides+keying ;


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negotiate an appropriate schedule $ith the computer operations staff.

9. &he distribution o* all out$uts must be s$eci*ied. :or each output, the recipients of allcopies must 'e determined. A distri'ution log, $hich pro!ides an audit trail for theoutputs, is fre3uently re3uired.

;. Access controls are used to control accessibility o* video (on/line) out$uts. :or e)ample, a pass$ord may 'e re3uired to display a certain output on a CR( terminal.

4. Control totals should be incor$orated into all re$orts. (hese controls can 'ecompared $ith the input controls that $ill 'e discussed later in the chapter. (henum'er of records input should e3ual the num'er of records output. (hese controltotals are compared 'efore the outputs are distri'uted. #f a discrepancy is found, theoutputs are retained until the cause has 'een determined and corrected.

In!e@e! se "ential a##ess metho! an! the !ire#t file a##ess metho!.(he inde)ed se3uential access method +#SAM is a $ay of storing data records on aphysical storage de!ice in se3uential order for se3uential processing +such as in payrollapplications . 5o$e!er, #SAM also allo$s any specific record to 'e directly accessed$ithout searching through the file se3uentially 'y using the recordHs key field to find itsstorage address in an inde).

The difference between batch and on-line processing

Batch processing in!ol!es 6'atching7 transactions together and then applying theseaccumulated transactions as a group or 6'atch7 at some later point to update a computer system master file. *n-line processing in!ol!es entering a transaction directly into thecomputer and processing it immediately. 1ith on-line processing, information in thesystem is al$ays up-to-date and current.;eal Time

)etho!s of intera#tin' /ith a system.

• #omman! lan'"a'e " A human computer interaction method $here users enterede)plicit statements into a system to in!oke operations.

•

)en" " A human computer interaction method $here a list of system options ispro!ided and a specific command is in!oked 'y user selection of a menu option• Form " A highly intuiti!e human-computer interaction method $here'y data fields are

formatted in a manner similar to paper 'ased forms.• O e#t9 A human computer interaction method $here sym'ols are used to represent

command or functions.• nat"ral lan'"a'e9 A human-computer interaction method $here'y inputs to and

outputs from a computer 'ase application are in con!entional speaking languagesuch as English.

Fo"rth 'eneration lan'"a'es

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8Fo"rth 'eneration 8 languages are e)tremely sophisticated languages $hich ena'leend-users to perform programming tasks $ith little or no professionalprogrammer assistance or that enhance the producti!ity of professionalprogrammers. :or e)ample, !ery high-le!el programming languages, 3uery

languages, or application generators ha!e features that can 'e employed 'yend-users or less skilled programmers and can dramatically increaseapplication de!elopment producti!ity.

Cate'ories of fo"rth 'eneration tools.

(he se!en categories of fourth-generation tools are"

• @uery languages" high-le!el languages for retrie!ing data from data'ases andfiles $hich can support re3uests for information that are not predefined. (end to'e on-line and interacti!e.• Report generators" facilities for e)tracting data from files or data'ases to createreports in many formats.• raphics languages" facilities for displaying data from files or data'ases ingraphic format.• Application generators" preprogrammed modules that can generate code for input, !alidation, processing, update, and reporting $hen users pro!idespecifications for an application.• 4ery high le!el programming languages" perform coding $ith far fe$er instructions than con!entional languages.• Application soft$are packages" pre-$ritten application soft$are that is marketedcommercially.• Microcomputer tools" general-purpose application packages de!eloped for microcomputers, especially $ord processing, data management, graphics,desktop pu'lishing and spreadsheet soft$are.

5. TESTIN4 an! &EB 44IN4

5.1 TESTIN4

1hen a system is designed it is important that some consideration is gi!en to makingsure that no mistakes ha!e 'een made. A schedule should 'e dra$n up $hich containsa test for e!ery type of input that could 'e made and methods of testing that the programactually does $hat it $as meant to do. (his schedule is kno$n as the test lan . ?otethat it is produced 'efore the system is produced.(here are a num'er of $ays of testing a program.

1. Bla#: o@ testin'&ifferent


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9. White o@ testin' is testing the program to determine $hether all the possi'le pathsthrough the program produce the desired results. As a large program can ha!e a !erylarge num'er of routes, $hen you take into account the different condition statementsand loops, $hite 'o) testing is rarely carried out e)hausti!ely.

(hink of 'lack 'o) as a test $here you cannot see into the 'o) +program all you see is$hat comes out at the end. 1hite 'o) testing means that you are a'le to see $hat ishappening as the data goes through the 'o) 'ecause it is transparent.

Al ha an! Beta testin' . 1hen you ha!e $ritten a program and you sit do$n to test it,you ha!e a certain ad!antage 'ecause you kno$ $hat to e)pect. After all, you $rote theprogram. (his can 'e e)tended to the $hole soft$are company, as the employees are allcomputer-minded people. (esting carried out 'y people like this is kno$n as alphatesting. E!entually, the company $ill $ant ordinary users to test the program 'ecausethey are likely to find errors that the soft$are specialists did not find. (esting carried out'y the users of the program is called eta testin' .

Sele#tion of test !ata#f a solution is to 'e tested, someone has to choose $hat data is going to 'e used to dothe testing. (he test data is usually chosen 'y the programmer 'ecause they kno$ $hatthey $ant to test. #t is important to test as many different things as possi'le, theimportant $ord there 'eing OdifferentP. (he pro'lem for the programmer is that they kno$$hat inputs $ere e)pected so they find it !ery difficult to think of the sort of inputs thatthe user of the program might try to put in.

1hen you are asked to think up different inputs to test a program, it must 'e different

types of input, not ust changing num'ers. #magine a 3uestion that states that a programhas 'een $ritten that $ill $ork out the mean of three num'ers. >ou ha!e to come up$ith different test data and the reasons for !oin' those tests. (hat last 'it is in 'old'ecause that is $hat you get the marks for and the reasons for the tests are the thingsthat ha!e to 'e different. #n this e)ample you $ould may thinking of

F, 9, ; to test $hether integers $ill gi!e an integer ans$er F, 9, < to test $hether the soft$are can cope $ith a recurring decimal ans$er +?ote that 6F, 9, < to test a different set of integers7 $ould not get a mark 'ecause thereason for the test is not differentF, 9.0, ; to test $hether the program can use decimal inputs

F, 9 , ; to test $hether fractions are allo$ed-F, -9, -; to test $hether negati!e num'ers can 'e handledF, 9 to test $hat happens $hen only t$o !alues are input

(here are many more that $ould 'e accepta'le. (he important thing to notice is that thenum'ers themsel!es are almost identical 'ut that the reasons for choosing them are!ery different.

5.2 &e "''in'Errors in computer solutions are called 'ugs. (hey create t$o pro'lems. *ne is that theerror needs to 'e corrected, this is normally fairly straightfor$ard 'ecause most errorsare caused 'y silly mistakes. (he second pro'lem, ho$e!er, is much more complicated,

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the errors ha!e to 'e found 'efore they can 'e corrected. :inding $here the error is andidentifying it, can 'e !ery difficult and there are a num'er of techni3ues a!aila'le for sol!ing such pro'lems.F. (ranslator diagnostics. Each of the commands that are in the original program is

looked at separately 'y the translator. Each command $ill ha!e a special $ord

$hich says $hat sort of command it is. (he translator looks at the special $ord inthe command and then goes to its dictionary to look it up. (he dictionary tells thetranslator program $hat the rules are for that particular special $ord. #f the $ordhas 'een typed in $rongly, the translator $ill not 'e a'le to find it in the dictionaryand $ill kno$ that something is $rong. #f the $ord is there, 'ut the rules go!erningho$ it should 'e used ha!e not 'een follo$ed properly, the translator $ill kno$ thatthere is something $rong. Either $ay, the translator program kno$s that a mistakehas 'een made, it kno$s $here the mistake is and, often, it also kno$s $hatmistake has 'een made. A message detailing all this can 'e sent to theprogrammer to gi!e hints as to $hat to do. (hese messages are called translator diagnostics.

9. Sometimes the program looks alright to the translator, 'ut it still doesnPt $orkproperly. &e'ugging tools are part of the soft$are $hich help the user to identify$here the errors are. (he techni3ues a!aila'le include"

a. Cross referen#in' . (his soft$are checks the program that has 'een$ritten and finds places $here particular !aria'les ha!e 'een used. (hislets the programmer check to make sure that the same !aria'le has not'een used t$ice for different things.

'. Tra#es . A trace is $here the program is run and the !alues of all therele!ant !aria'les are printed out, as are the indi!idual instructions, aseach instruction is e)ecuted. #n this $ay, the !alues can 'e checked to see$here they suddenly change or take on an une)pected !alue.

c. *aria le !"m s . At specified parts of the program, the !alues of all the!aria'les are displayed to ena'le the user to compare them $ith thee)pected results.

;. &esk checking is sometimes kno$n as a dry run. (he user $orks through theprogram instructions manually, keeping track of the !alues of the !aria'les. Mostcomputer programs re3uire a !ery large num'er of instructions to 'e carried out, soit is usual to only dry run small segments of code that the programmer suspects of har'ouring an error.


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5.3 Installation Inte'ration Any system needs to 'e tested to ensure that it $orks. (his seems to 'e a fairly o'!iousstatement, 'ut in reality such testing is impossi'le in all 'ut the simplest of systems'ecause it simply is not possi'le to test e!ery concei!a'le input to, or logicalconstruction in, the system. (his difficulty means that testing that is to 'e done must 'ecarefully planned and that it should relate directly to the criteria referred to earlier in thissection.

1hen the system has 'een completed it has to 'e implemented so that it is performingthe tasks for $hich it $as designed. #nitially, this in!ol!es• ensuring that the correct hard$are is a!aila'le• arranging for staff to 'e trained in the use of the ne$ system• inputting the data to the data files, either manually or 'y do$nloading them from the

original system.(he system hando!er, itself can 'e done in a num'er of $ays"• +arallel r"nnin'. ntil the system can 'e considered fault free, the old and ne$

systems are run side 'y side, 'oth doing the same processing. (his allo$s results to'e compared to ensure that there is no pro'lem $ith the ne$ system. Such a systemis OsafeP and also allo$s staff training to 'e carried out, 'ut it is o'!iously !erye)pensi!e 'ecause of the need to do e!erything t$ice. arallel running is used insituations $here the data is so !alua'le that there must 'e no possi'ility of failure.

• +ilot r"nnin'. Gey parts of the ne$ system are run alongside the old system until itis considered that they ha!e 'een fully tested. (his is a compromise $ith the idea of parallel running, 'ut it does not gi!e a clear idea of the effects on the system of thelarge amounts of data that are going to 'e encountered in the full application.

• Bi' an'> or !ire#t #han'e. (he old system is remo!ed and the ne$ systemreplaces it completely and immediately.

• +hasin' . arts of a system are replaced $hile the remaining parts are co!ered 'ythe old system. (his allo$s for some testing of the ne$ system to 'e done, and for staff training to take place, 'ut also allo$s for a 'ack-up position if the ne$ !ersiondoes not $ork as anticipated.

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A++EN&I A

SSA&M D Structured System Analysis and &esign Methodology

rinciples of SSA&M&' &ata &ri!en2' Logical and hysical Concepts are separated3' #terati!e &e!elopment#' Logical to hysical Con!ersion in rescripti!e$' erformance Estimation and *ptimisation 'efore #mplementation%' Acti!e ser #n!ol!ement(' (op-do$n Approach8' Regular Re!ie$s

SSA&M #nput D Statement of Re3uirementsSSA&M *utput D rogram Specification

:ile &ata Base Specificationsser and *perations Specifications

; Analysis Stages; &esign Stages

(echni3ues used in Methodology&:&s D &ata :lo$ &iagram+sL&Ss D Logical &ata StructureEL5s D Entity Life 5istories

rocess *utlines(?: D (hird ?ormal :orm &ata AnalysisFst Cut &esign Rules

lus, @uality Assurance Re!ie$ and :ormal &ocumentations

(he aims of SSA&M"• Better pro ect structure, leading to 'etter planning• More effecti!e use of ine)perienced staff • Better control and monitoring of progress resulting from task 'reakdo$n• Closer user in!lo!ement• Better communication $ith user through documentation• 5igher 3uality of analysis and design leading to potential lo$er costs• &emonstra'ly pro!a'le systems design logic

Structural frame$ork of SSA&MSSA&M consists of three phases" feasi'ility, +optional

analysis and design

Each phase is di!ided into stages andEach stage is di!ided into steps.

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(hese in turn are di!ided into tasks.

SSA&M Structure

hase F

:easi'ility StudyStage F D ro'lem definitionStage 9 D ro ect identification

hase 9Systems Analysis

Stage F D Analysis of systems operations and current pro'lemsStage 9 D Specification of re3uirementsStage ; D Selection of technical options

hase ;System &esign

Stage < D &ata designStage 0 D rocess designStage = D hysical design

sad complete

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