Whitten & Bentley (2007) System Analysis and Design Methods - 7th Edition PDF

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JeHrey L. Whitten Professor )> ::J Lonnie D. Bentley Professor 0 -< U> Both at Purdue University West Lafayette, IN - · U> With contributions by 0 GaryRandolp? ::J Purdue University Q_ 0 CD SEVENTH EDITION U> co ::J s CD --t- ::J 0 Q_ U> ID McGraw-Hill ttJ1jj Irwin Boston Burr Rid...

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JeHrey L. Whitten Professor Lonnie D. Bentley Professor

Both at Purdue University West Lafayette, IN

With contributions by GaryRandolp? Purdue University

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SYSTEMS ANALYSIS AND DESIGN METHODS Pllblisb?d by McGraw-HiJVIrwin. a busins u.nitofTbe McOraw-HilJ Companies. h'lc.. 122 I Avenue. of the Americas. New York. NY )>)020. Copyright () 2007 by The McOraw-HilJ Companies, Ioc. AUrights NSer.\"d. No put of this publication may be repiOduced or distributed in any form or by any means. or stored in l database or retrieval system. witlx>ut tho?. prior written consent of The McOraw-HilJ Companies. h'lc.. iocludiog. but not Limited to. in any D?twort: or other elec:tlonic storage or transmission. or broad:ast for distanoe.learning. Some ancillaries, including electronic aiXI print components. may rot be. anilable. to customers outside tho?. United Slates. This book is p-inted on ocid-free paper. 123 4 567890VNHNNH 0 98765 ISBN-13: 978-0-07-305233-5 ISBN-10: 0-07-305233-7 Editaial director. Brettt Gordo11 Executi\\". editor: Pard Duchont Projoct manager: 1Wna Hauger Marketing manager: Satlkha Basu Media producer: Greg Baus Projoct manager: Kristin Bmdley Lood prOOuction .super.•isot: Micltoel R. McCof'I.Tiit:-k Senior desigper: Kami CarJer Photo research ccxxdinatot: lhri Kramer Media project manager: LyM M. Bluhm Cowr de.sig1.1: Komi Carter Interior design: Kami Carter Cowr image: C Cabis

Typeface: 10112 Garamolfd Light Compositor. ~Los Mgtles, CA. Campus Printer: ~" H Changes for the Seventh Edition Reorganization for Better Clarity> The object-oriented analysis d>apter has become 01apter 10 to better position It alongside the structt>red analysis chapters (Chapters 8 and 9). Other chapters ha>.. been reorganized Internally. For example, Chapter 9,ln response to reviewer commen(S, has undergone extensive reorganlntlon. Also, me discussion of sequential versus Jteratlve deveJopmenr has been moved to 01apter 3 to pL1ee It with related methodology concepts. E."e object-rlented analysis chapter (Oupter I 0) features expanded co,.. rage of activity diagrams. New to this edition In Chapter 10 Is coverage ol system sequence dlllgrnms. Oupter 18 features expanded coverage of objectoriented design. Persistence and system design dasses are discussed as well as entlry, comroller, and lnterface design classes. 111e discussion of sequence dlagrams and CRC cards has been expanded, and their role In the design process explained more fully. Coverage of design patterns llas been greatly expanded with a dlscl~slon of the Gang of Four patterns tnd an examination of two of the patterns. UML 2.0, Both Chapter I 0 and 01.1pter 18lm-e beetl revised to cover the UML 2.0 speclllcatlon. Each UML 2.0 dL1gram Is listed with an explanation of Its purpose. In Chapters 7, 10, and 18, lh-e of the thirteen UML 2.0 diagrams are developed in depth and three more are shown and discussed. E."lng guidelines and PowerPolm slides, tempL1tes, and answers to end~fetworkahle for LAN test administration. Each chapter offers 75 questions In the following formats: true/false, multiple choke, sentence completion, and matching. The test b.'lnk and answers are cross-referenced to the page numbers in the textbook. A levek>f-dlfflct~ty rating ls also assigned to each question.

>Packages

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Student Resource co

Ead1 text Includes a student CD with two case projects, templates and forms for the projects, the same PowerPoln~ slides provided to the Instructor, and a 12o.day evaluation copy of Mlcrosoft Projec~ accompanied by a stepby-step tutorL1l.

'o System Architect Student Edition Version 8

An optional package comhlnes d>e textbook, Student Resource CD, and a student version of System Architect. System Architect ls a powerful, repository-based enterprise modeling tool which supports a comprehensive set of dlagrammlng tedmlques and learures, Including all nine Ul\IL diagram types, business enterprise modeling, data modeling, business modeling with IDEFO and IDEF3 notations, plus many more.

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Visible Analyst Workbench

Anod>er optional package combines the textbook, Student Resource CD, and VisIble Analyst Workhench. This tool integrates businessfw>ctlon analysis, data modeling and database design, process modellng, and object modeling In one easy-t-are

Development EtJ-vlro1mwnt 500 Application Architecture Strategies for Sysrc.ms

Design 502 The Emerprfse APPifcatton Architecture Strategy 502 The 'ractlcal App/icatlotJ Architecture Strategy 503

Modeling the Application Ardutccture of an lnfornution System 503 Draw111g Phvslcal Data Flow Diagrams 504 Prerequisf.tes 504 The NeTwork Architecture 505 Data LXstrlbutlon and 'Jechnolosv Assignments 506 Process Distrf.bution ar~d Teclmolog v Asslg1tments 507 The Perso11/Macbit1.e Boundarl.es 510

----~1_4~D=A=TAB ==A=S=E=DE=S=IG=N~S~1~6----~) Introduction 518 Conventional Fucs ''e communications gap that can naturally develop bem-een the nontechnical ~tern owners and users and the redmlcal sysc:em designers and builders. All the above srakeholders have one thing In common- they are whar the U.S. Department of Labor calls I.Jtform.~tlou workers. The U>-.Uhoods of Information wod:ers depend on decisions made based on information.Today. more than 60 percenr of the U.S. labor force Is Involved hl producing, dlstrlbuth1g, and ush1g Information. Let's examine the five groups of lnfonnation workers In greater detail. Let's briefly examine the perspectives of each group. But before we do so, we shotid point om tl1.1t these groups actuaUy define "roles" pL1yed In systems development In practice. any indJvJdual person may play more than one of these roles. For example, a system owner ntlght also be a system user. Slm1L1rly, a systems analyst may also be "- system des:lgnec,

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a s:ys:tem designer m.igtu also be "- system builder. 1\.ny

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Systems Owners

For any lnformation $)'stem, large or small, there will be one or more system owners. Syst:em owners usually come from the ranks of management For medlum to Luge inforrmtlon sysc:ems. $)'SC:em owners are usually middle or executl,.-'e managers. For smaHer systems. system owners may be middle manacers or supervisors. System owners tend co be Interested In the bottom line-how much wiU the system cost.? How much '\o-a.lue or wbar benefits wiU the system return 10 the bush1ess?Value and benefits can be measured In different ways. as nored h1 the margin checklist:.

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Systems Users

System user-s make up the vast majority of the Information worle functlooaUty tl>e system pro>ides to their Jobs and the system's ease of leamlog and ease of use. Although users have become more rtdmology-literate O\o"'et the years.

expen S}'Stem an informa. tion system that captures the expertise of workers and then simulates that e: ~

System owners pay for the aystem to bf built and o pelllted end eel

the vision and priorities forthe aystem, He'lce, they v iew an information system in terms of Cl08ta and benefits to solve problems and exploit opportunities,

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SYSTEM USEAS ' V l EW O FTHE INFORMATION S YS TEM

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SYSTEM DESIGNERS' VIEW OF THE N FORMATION S YSTEM

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fea-sible technical solution, Hence, theyv l&w an information 8)6t&m in terms of a design blueprint to guide the construction of the final eystem.

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SYSTEM BUILOEAS' VIEW OF THE INFORMATION SYSTEM System build er• oorutruct, deploy, and ma intain the information system, Hence, they tend to view an information system in terms of the actual working hardware and aoftwareto implement the evstem,

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F I G U R E 1 - 1 Stakeho lders' Perspective of an Information System

system owoer an inforrna. tion syS1em's sponsor and executive advocate, usually responsible for funding the project of developing, operat· ing, and maintaining the information sy31em.

their primary concent is to get the job don e. Consequently, discussions with most users need to be kept at tl>e business requirements level as opposed to the technical requirements level. Much of tllls book Is dedicated to teaching you how to effectively identify and communicate business requirements for an lnfonnatlon system. T here are many classes of Sj'stem users. Each class should be directly itwoh--ed in any Information system developmetll project that affects them. Let's briefly examine these classes.

Tllo Context of Systoms Anolysls and Dosf!p> Mothods lntetnal System Users lmernal system users are employees of the businesses for which most information systems are built.. lnrernal users make up the largest percenuge of information $)'stem users In most businesses. Examples lndude: Clerical and urvf.ce workers- perfonn most of the day-ro-day ttansactlon processh1g ln the average business. They process orders, Invokes, payments, and the Ilk e. They type and file correspondence. They fill orders In the

warehouse. And they manufacture goods on the shop floor. Most of d1e fundamemal data In any business is capcured or created by d1ese workers, many of whom perform manual labor In addition to processing data. Infor-

mation systems that target these workers tend to focus on ttansactJon processing speed and accuracy.

Tecl.mtca/ and professional staff- consists largely of business and lndustrL1I specL1IIsts who perform highly skilled and spedallzed work. Examples Include lawyers, accotuuants, engineers, sdentlsts, market analysts, advertlshlg designers, and statlstidans. Because d1elr work Is based on well-defined bodIes of knowledge, they are sometimes caUed knowledge workers. Information systems that target rechnlcal and professional staff focus on data analysis as well as e:eneratlne: tlmeJy Information for problem solvine:. Supervisors, middle managers, and e.wcu.tlve mauagers- are the dedslon makers. SUpervisors tend to focus on day4o.s lnfonnatlon ~ems to detennlne our supply needs and amomatlcally create orders to tlll those needs.1l1ere is no Jo~er always a need for an lnrero.al user co l.nltlate those orders co a supplier. ParmMs- any organizations from which our company purchases senices or wtth which tt: partners. Most modern businesses conuact or outsource a munber of basic services such as grow1ds maintenance, network managemem, and many others. And businesses h.a,.--e learned to panner wich other businesses to more quickly leverage strengths to build better products more topldly. Employees- those employees who work on du road or who work from borne. For example, sales representatives usualtl spend much of d1eir rime on the road. Also, many bush1esses permit workers co relecommure (meaning "work from home") to reduce costs and impto'le productivity. As mobile or remote users, d1ese employees require access m the same information systems as those needed by lmernal users.

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POSSIBLE VALUES AND BENEFITS OF INFORMATION SYSTEMS

Increased Business Profit Reduced Bus ness Cosls Cosls and Benefits of lhe System Increased Ma'ket Share Improved Customer Relations Increased Effi,: iency Improved Oe-acy). 'fllcl.mo/ogy specia/fsts- experts In the application of specific tedU>ologles that will be used In a system (e .g., a spedftc commerdal software packace or a spedftc type of hardware). >

system builder a technical specialist who constructs information syst~ms and components based on the design specifications ;~enerated by the system de.signers.

Systems Designers

Systems Builders

Syst e m b uilders (ag.1ln, see Fll!llfe 1-1) are another category of tedmology sped allsts for information ~ems. Their role is ro constrlK1 the ~em accordtn.a to the system designers• spedtkarions. In S'IThlH organ.izatioos or wlth smaH Information systems, systems designers an d systems builders are often the same people. But In large org.1nlzations and Information systems tl>ey are often separate Jobs. Some of you may be educating yourseh·es to specialize in one of d>elr technical speclalties, such as: Appllcatf.o11S programnwn- speclallsts who convert business requirements

and staremenrs of problems an d procedures Into com purer languages. They develop and rest comp urer programs to capture and srore data and to locate and retrieve dara for computer appUcatloos. S):stems programmers- spedaUsts who develop. rest, an d implemenr operating systems-level software, utllltles, and services. Increasingly, they also develop reusable software "components• for use by applications prognmmers (above). Database programmer.s- spedalists in database languages and technology who build, modify, and test darabase strucrures and the programs that use and maintain them. Network admiuf-Strators-speclallsts who desJgn, lnsrall, rroubleshoor, aod optimize computer networks. Secu.rf.ty adml11istmtors-spedalists who design, irupJemenr, rroublesho«, and manage security and prh--acy conrrols In a network.

Tllo Context of Systoms Anolysls and Dosf!p> Mothods

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Webmasters- spedalists who code and maintain Web servers. Software Integrators- specialists who Integrate software packages with hardware, networks, and other software packages. Although thJs book Is not directly Intended to e tended to teach ~tern designers how to better communicare design specl.tlcatlons to system builders.

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Systems Analysts

As you have seen, system owners, users, designers, and builders often have '\o-ery dJf. ferent perspectives on any information ~·stem to be built and used. Some are interested ln generalltjes, wbUe others focus on details. Some are nomecbnical, while others are very technlcal.11lls presents a commwlications gap that has always existed bet\,.:een dtose who need compurer-based business solutions and those who understand lnformation technology. The S)'Stems auatys1 bridges that gap. You can (and probobly wlll) play a role as eltl1er a systems analyst or someone who works wltll sys. tems analysts. .As IUu.sb':ued In Figure 1 t, their role lnrention..·dly overl'lp6 the roles of all the other stakeholders. For the ~·stem owners and users, systems analysts Identify and '\o-:tlidare business problems and needs. For the ~·stem designers and builders, systems analysts ensure that the recbnJcal solmion fulfllls the business needs and integrare the tedutical solution Ioro the business.ln other words, :;ystems analystsjacfJttate d1e developmem of Information syst:ems dvough interactla.l wlth the other stakeholders. There are several Jegttlmate, but ofren confusing, variations on rhe job tide we are calllog"systems analyst.• Aprogramt>wr/anafJ•t(or analyst/programmer) Includes the responslbllltles of both the computer programmer and the systems analyst. A bust1wss mtalyst focuses on only the nontechnlcal aspects of systems analysis and design. Other synonyms for "~terns analyst• are systems consulrant, business analyst, systems architect, ")'Stems engineer, information engineer, infonnation analyst, and systems lmegrator. Some of you will become ~·stems analysts. Tile rest of you wUJ routinely work with systems analysts who will help you solve your business and industrial problems by cteatlng and improving your access to the data and infonnation needed to do your job. Let's take a closer look at systems analysts as the key faclUtators of Wormatlon systems development.

The ~ole of the Systems Analyst Systems anai)•Sls understand botl1 business and computing. They srudy business problems and oppommltles and men uansfonn business and information requirements into spedflcatioos for information systems d1..1t will be Implemented by various tecbnlcal specialists Including compmer progran> mers. Computers and lnformatlon ~·stems are of value to a business only lf they help solve problems or effect impro\o-ements. Systems analysts initiate chm1ge wtthin an organJzatlon. E\o-ery new ~tern dtanges the bush>ess. Increasingly, the very best systems analysts literally change thelr organlzatlons- pro"idfng information d1..1t can be l!Sed for competitive advantage, finding new markets and services, and even dramaticilly changing and huprovlng the way the organization does business. The systems analyst Is basically a problem solver.1llroughom this book, the term problem wUI be used to describe many situations, Including: Problems. either real or antidpated, thar require corrective action. Opporrmllties ro improve a situation desplte the absence of compL1ints. Directives to d1..1nge a situation regardless of whether anyone has compL1ined abour d1e current slmatlon. The systems analysrs job presents a fusch>.1th1g and exdtlng cl>.11lenge to many Individuals. It offers high mat>.1gement visibility and opportunlties for Important

systems ao.al!•st a special· ist who s tudies he problems and needs of an organization to determine haN people, aata, processes. ana rmorma. tion technology :an best accomplish improvements for the business

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Tho contoxt of Systoms Dovolopmont ProJOess and technical speclfl. cations for a programmer if they didn't have some programmhlg experience. Most ~tems analysts need ro be proflclenr in one or more high-level programming languages. General Jm.owledge of bu.stness proa1sses aud temttnology- Systems antlysts must be able ro communicare wfili bush1ess experts ro gain an understanding of their problems and needs. For the analyst, at least some of tills knowledge comes only by way of experience. At ti>e same lime, aspiring analysts should avail d1emselves of every oppormnlty to complete basic bush1ess Uteracy courses a"-allable h1 coUeges of business. ReleYanr courses may include financial accow1ting, managemenr or cost: accotmtlng, finance, marketing, man. ufacturhlg or operations nunagemenr, quality management, economics, and business law. General problem.solvt11g .will Mothods