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PERSPECTIVE Computers

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As mOie and better designers are needed, universities and industry are under pressure to establish programs to train them

years will coinpete with large conventional in software , Among them are puters in particular become an inexorable computers and require extensive software Seattle University in Washington; Texas part of more and more new equipment, a support. Christian University in Fort Worth; Dart• new type of engineer is growing in impor• Also contributing to this crisis is the mouth College in Hanover, N.H.; and the tance. Bearing the title "software engi• fact that and Wang Institute of Graduate Studies in neer,' he or she is part and maintenance problems are compounded Tyngsboro, Mass. Companies like IBM!, pan systems-hardware and -software de• because most microprocessor software is Bell Laboratories; and TRW have also sign engineer, among other things. not portable from one microprocessor to developed educational programs in this Industry and government agencies C,Ul• another. Tnese systems are usually designed area. not find enough ofthem, and the need for with large sections of code written in Many university them is critical. Softw~r~ is !!0~ such a machine-dependent languages, resuiting courses are taught from notes that pro• vital part of operating equipment- in programs that can be used by only one fessors have collected from engineers in whether electronic field testers or automo• microprocessor family. Proprietary lan• industry and government. There are few biles-that it must be designed in parallel guages and development systems tend to books on the subject, though articles on with the hardware from the outset if cost• lock the equipment manufacturers into a the multidisciplined field have appeared in ly, unreliable trial-and-error software with particular line of chips and systems. Also, professional journals, including the IEEE limited performance is to be avoided. compilers generally lag behind hardware Transactions on Software Engineering The software engineer is a computer system development by a year or more. and IEEE Transactionson Computers, as jack-of-all-trades. He understands both But as great as the demand for software well as various ACM publications. The hardware and software and can mesh the engineers is today, it is expected to grow IEEE Computer Society Technical Com• two smoothly for optimum performance. many times over during the next several mittee of Software Engineering sponsors Ideally, he becomes involved in the hard• years. international conferences on software ware and before the sys• An accurate tally of the number of engineering and publishes tutorial books. tem gets on the drawing board. these engineers in the U.S. at present is Most software engineers come from the not available. Some idea of the total can ranks of computer , com• I. The demand is rising perhaps be gleaned from membership and puter scientists, and electrical and What has pushed the demand for these publication subscription lists of the pro• mechanical engineers. new engineers is the "software crisis," or fessional societies. Statistics from the the high cost of redesigning defective or IEEE and the Association for III. The job specs outmoded software, along with growing Machinery (ACM) indicate that 15 700 In general, software engineers view a distrust among users of software because members of the IEEE Computer Society system, with iiS operating hardware and of delivery of poor packages. The crisis receive the IEEE Transactions on Soft• software problems, as an integrated was caused in part by a slow advance in wareEngineering and that there are about whole. They must be familiar with elec• software during the 19705, 7000 members in the ACM Special In• tronic specifications, design analysis, when semiconductor technology advanced terest Group O!1 Software Engineering quality control, and environmentai re• rapidly, Microprocessors and other hard• (Sigsoft), quirements. Unlike programmers-s-who ware devices, on the other hand, have cut Whatever the actual total, Barry are mostly involved in the relatively nar• the cost of equipment and opened up a Boehm, director of the office of software row field of writing codes, designing proliferation of applications. and technology in the TRW algorithms, and working with computer New microprocessors like rnters 8086, System Engineering and Integration Divi• languages-e-software engineers must see Motorola's 68000, and Zilog's Z8000 will sion, predicts that "by 1988there will be a the big picture. require software systems more complex need for double the number of software Their work can range from systems us• than most minicomputer systems to ex• engineers currently in the field." ing microprocessor technology to very ploit their high performance and memory In spite of the growing demand, few large multiprocessor computer systems. capacities. The micromainframe devices steps have been taken to train software They work on total system design, in• that will arrive OJ! the market in a few engineers. cluding subsystems, systems using either off-the-shelf or custom electronic hard• II. Formal training lags ware, process-control systems, computer• Joel Fagenbaum At present only a few institutions in the aided manufacturing, and computer• Associate Editor country offer formal graduate education aided instruction-in short, they deal with

62 OO! 8-9235/81/0800-0062$00.75 © 1981 iEEE IEEE spectrum SEPTEMBER 1981 just about every computer and microcom• disciplines, and business practices. new joint meetings of systems hardware puter application. They are most impor• Program design may involve queuing the• design and software engineers, new tant when large complex systems are in• ory, , operating negotiating, and new solutions. volved, such as strategic weapons systems, systems, and programming languages. In large software projects, the software space, electronic funds transfer.. and mass For tile negotiation process, the disci• engineer is immersedas well in written and transportation systems. plines include cost estimating, budgeting, oral commurucanons-e-prepanng propo• and . sals, work statements, system documenta• engineer because of the relationship be• Under optimum conditions the. soft• tion, and maintenance reports. He must tween computer architecture and the ware engineer meets with the system hard• act as a technical liaison with other com• structure of operating systems and soft• ware design engineers while the design is panies and interface with systems hard• ware. He may need to specify new forms still under discussion. At this stage ware and software engineers, as well as of hardware to implement a project changes in hardware may make the soft• with nontechnical persons such as design. ware more effective. Together the engi• business managers in the government and On a typical working day the software neers analyze tradeoffs, negotiate dif• university sectors, engineer interfaces with people in dif• ferences, and try to arrive at a final, ferent engineering disciplines as well as in reliable design that will pose few main• IV. Typical applications other fields. He must also be competent in tenance problems. Large complex software systems such management techniques and industrial en• Most errors in large industrial software as operating, navigation, industriai con• gineering. This means an ability to development systems, it has been found, trol, communications, computer-aided organize, estimate, and use the skills and occur in the early stages of design. Here manufacturing, computer-aided design, knowledge ofother people and to eSihnate design errors considerably outnumber management information, and medical resources to accomplish objectives. coding errors and it is important to nip data-base systems all interface with peo• This engineer uses several kinds oftools them in the bud. As a project advances ple. The software engineer has to be able tn------r----~~~nrnn1ic:h thrpp------"'!:lin t!:lC:1cc:·------!:Innllr~_--,.,.---- from !,re1imin~ry to detailed design the to evaluate how people react and behave tions solutions, program design, and cost of correcting sofware errors increases when interacting with these electronic negotiation with other engineers in the considerably. systems. "The software engineer design• organization. For applications solutions, Nor does the software engineer's job ing, for instance, a patient data-base the software engineer may use numerical end with the completed design of a prod• system for a hospital has to know what analysis, mathematical optimization, sim• uct. It continues while the product is being data a doctor needs and what information ulation, modeling, information theory, built. Unexpected problems may call for nurses, technicians, and paramedics re- ,.---[ lL ll_J~ l[ II J~ Ope!~~ons S¥stem So!'ware Pre!imin!'ryl Detailed I Cl)Cf" And IJ. Test and I .-.1 requirements rsqutrements design design debug preoparations main~~~ance

Validation Validation Validation Validation Unit test and Validation test Revalidation integration

[l] Software engineering covers the entire 80 software life cycle shown above, including 1 c=l Linker/loader I redesign and modification or software n maintenance. 70r _ Real-time application _ Environmental simulator ~ [2J At right aresoftware errordistributions 6+ and their variations by applications area in I 1 three portions ofa largesoftware project, 50tl all with comparable size, personn"el, and management techniques. Most ofthe errors 40 j in the systems (linker/loader) portion are II logic errors. But snftw(1!'f! reliability is not simply a matter of applying techniques, 30~ such as structured code, to help avoid logic errors. In developing applications pro• j grams, logic errors make up only a small part of the total errors software engineers ::~ must avoid. -~ oLL.!.. Computational Logic Data-handling I/O Data-base Interface Other Type of error

Fagenbaum-A new breed: we software engineer quire. ,. explains Roland Mittermeir ofthe computer terminals can be tolerated by system. Once that is clear to him, his University of Maryland's computer doctors in hospital rooms-the hospital responsibility is to come up with the soft• science department. staffmight prefer light pens, for instance, ware that will take everything into ac• He is concerned with questions like the for interacting with the data-base system; count, properly instruct hardware, pro• following: How long should the data be and of tradeoffs between cathode-ray• cess data, and deliver meaningful stored in the data-base system? When tube displays and paper file systems. output. 77 does an entry become meaningless? How The number and complexity of micro• The software engineer plays a Com• fast must the data base respond to an in- processor applications-and consequent• parable role in the aircraft industry. He quiry? Is a distributed data base more ad• ly of related software packages-c-are has been u~d in the design of communi- vantageous than a central data base? Must increasing, especially in automobile ap• cation and guidance systems for new air• the system operate 24 hours a day, seven plications. "The engine control systems craft and has helped design the airborne days a week. or can the hospital require• designed into our cars use anywhere from command and control systems in advanced ments be met, say, in 20 hours a day, six 7 to 10electronic sensors that monitor dif• warning and control systems (Awacs) air• days a week? Also what kind of backup ferent variables relating to engine opera- craft;; ..At the Boeing Computer Services system is required? How much fault can Co. hi ~atti~, Wash., Leou Stucki, man• the patient data...base system have? Temple, supervisor of the Computer ager of the Software Engineering, Tech• "The amount of tolerable downtime is Systems Group at the Ford Motor Co.'s nology, Space, and Military Applications an important factor in any large software Research Scientific Laboratory in Dear.. Department, is familiar with the new system. Just imagine the situation that born, Mich. "The characteristic of these trend. develops when an electronic fund-transfer sensors might be linear, nonlinear, or "We are stressing the need to include system in a bank goes down. If it takes a iltnp_u!.:IrU'i1"\cw...... ,; ..··0· software engineering concerns at the begin• long tiil1e for the system to come up again, ;;;; Tnese sensors interfacewith the control ning, when a team of engineers meet to or for a backup system to come on line, system electronics by means of analog-to• specify the capabilities required of the queues of bank customers start to build digital converters. But the real difficulty aircraft," he relates. "The team may up; th~y e~! !!!!P~!!~!!! and annoyed, and li:i~ii.iuc antenna, radar, and power-supply you end up with an intolerable state ofaf• process all the raw data from these sensors designers, instrumentation,communication fairs-especially if the problem occurs to get useful results and yet take into ac• engineers, and other groups, as well as frequently," Dr. Mittermeir says. count each sensor's characteristics and software engineers. They consider system "The state of information stored in a limitations. This is where the software en• design parameters, such as radar antenna patient data-base system," he continues, gineer comes in. beam patterns; the way the radar system "has to be evaluated by the software "He has to know the behavior ofthese has to look at the ground; the kind ofsen• engineers. Medical data should be ar• sensors, their responses under different sors needed to track other aircraft-heat, ranged in a consistent state. In processing conditions, what information is desired by radiation, EMI, or RFI; and how to information, data-base systems might the engineers designing the engine control mathematically process the raw data from perform some statistical operations on the input medical data and store the result in memory. These operations are termed the [3] The cost ofcorrecting software errors escalates rapidly through the software life cy• inconsistent intermediate states of the cle. The data emphasize the importance of detecting and correcting requirement and software system. Depending on what the design errors before generating much code. health professionals want to evaluate, the software engineer then has to determine 100r------y-----~----__._-----r_----_r_----_.. the consistent state (whether it be a final state or some intermediate state) the data will have. This then becomes the response 50 Sources of the data base to all operator inquiries iBM-SDO •I into the system. TRW "The data base also has to be designed GTE Bell Labs to avoid concurrent data updates. This e 20~ Ci3 ~ refers, for example, to the change in situa• U tic" thai Occurs when a patient is moved ~ 0 from intensive care to a regular room. The u frequency and amount of data required .9 (j) 1:t 0 for his care is reduced somewhat. o "Once the design gets under way, the ~ -I I J I m software engineer has to delegate various Q5 tasks on the project to different people, 0:: / I I Ir manage the operation, and even be con• ] ____ 1 cerned '!.1t!1 the productivity of his pro• / grammers. For example, are they gener• / ating enough code, and is it good code?" ? Setting up a hospital information sys• tem also involves questions of specifica• :r Preliminary Detailed Code and Integrate Validate Operation tions for security, privacy, reliability, design design debug maintainability, size, and cost; ofwhether Phase in which error is detected

64 iEEE spectrumSEPTEMBER 1981 University growing pains Instruction in software engineering is still undergoing growing industries;" Prof, Lee s~Y~' "B~~~;y~:~ the ~'2~;e!:~ ~~tter is in a pains at universities in the United States. "Much of the latest state of flux~ the number of tAxth{jtjk~ ;t\i~ilFihIA is nllit~ ~m~1I technology is still not we!! documented," says Professor An: Studeiits mu~t read several books '~nd many j~~r~ai-'arti~iesfo~ thony Wasserman, a medical information specialist at the Uni• each course. versity of California at San Francisco. "A few well-designed sys• The three top disciplines represented by students in the pro•

tems must serve as models 10f other more complicated gram t according to Prof. Lee, are (33 percent), COrT} projects." puter science (21 percent), and (18 percent), Few university faculty members have had experience in Fifteen percent of the students already have advanced degrees developing commercial software packages, Prof. Wasserman in these fields. says, and such practical experience is valuable in teaching "It is interesting," Prof. Lee adds, "that over 90 percent of the students about the probiems and concerns of industry. students haa an ecucanonat backaround in areas which reauire "Tnen, too, there is a poiiticai probiem in some universities," an analytic discipline. About 49 percent of the students enrolled the professor goes ofI, "regardiflY whu shouid have coniroi over in the program worked in sctentmo a,net/or eng~neer!ng applica• the new discipiine. The department in most tions. The student population represents some 25 companies in schools has the faculty expertise to teach software engineering, the Seattle metropolitan area." but there are engineering and computer design departments at Recently the Wang Institute of Graduate Studies in Tyngsboro, universities where this discipline can also be taught. Manyof the Mass., was awarded degree-granting authority by the State instructors in those departments feel that software engineering Board of Higher Education. The institute is now authorized to is a 'subfield' and should not be set up as a separate discipline grant a master of software engineering degree, reports Nancy a;ong with computer science,mechanlcal angh,ecr;r~g,civil €ngi• rwiart'n, an associate professor of mtormauon teconoiogy. neer!ng, physics, and math." "The proqrarn iii software engineering," she says, "combines Fitting the new instruction into the teaching schedule may theoretical and practical tools and techniques for each subject. raise further oroblems. "It takes more time to teach software Each course requires both computer and paper-and-pencil exer• engineering courses than to conduct c-omputer science pro- cises and projects. The students learn to use and evaluate nr::lm~ W.Q~~erm~n ~ ....".h,.:...... 1 ... _,.a ...... 4 ._~ ... __ 1_ "T'L._•• 1 .LL. __._! ~ ... L_ " Prnf nntec: _.~~.v_. ~\,I""'IIIQ'wU 'VVI~. IllwI ICelll1 L1le \:)\"ICII\"C ClIIU Lilt: t-r~e b~a"iJ~e's~ft~a~e-~naineers ...... _..u g- Ttiis is work with unbounded engineering of producing software." problems-that is, problems where solutions are not clearly defined. Computer scientists, on the other hand, work with con• Twooptions for students crete specifications for part of a system, and the problems are Most academic programs in software engineering are similar better understood. Extra time that instructors must spend on in that they offer two options-a technical one for those software engineering lessens the time for research, writing, and students who want to work in the development or maintenance administrative duties. "Even introducing software engineering of software systems and a managerial one for those who want to courses at the undergraduate ievei is not so easy to do," Prof. plan, schedule, and control the development of software W::l~~~rm::an ~::IV~ "ThAr~ wnlliti no little rnnm left in tho I"lIr_ systems by others. To make sure that all students develop at ~iC~I~~'f~~'ali-~iher'r~q~ir~d-~;u~~~:'i'~~I~di~gth~ iib~~~ ;rt~ least a working knowledqe of the necessary technical and courses engineering students are obliged to take. Most typical managerial skills, in all programs students must take a set of engineering programs have minimum requirements for liberal core cou rses. arts courses. Should they be reduced even more? Software engi• There is a life cycle process covering such topics as analysis, neering stands today in the same position that computerscience design, development, maintenance, and testing. Management education was in about 15years ago-that is: still in the precess courses covei orqanlzatlon behavior, organization theory, soft• of being defined." ware projects management, and other areas. Strong emphasis has been placed on the management, according to Prof. Lee, SeaUle University off&rsdegree because much of software engineering activities take place in One of the few university software engineering programs in organizations. the U.S. is the three-year-old master of software engineering pro• He also feels that regardless of whether a person is in a gram at Seattle UniveiSity. Prot Kyu Y. Lee, director of the managerial track or a technical track-that is, if he or she is a program, notes: manager or is managed-that person should know certain prin• "An acute shortage of people able to develop software ciples of management as well as of organizational behavior. systems caused many companies in the Seattle area to start Therefore all students must take organizational behavior or their own ir'airlinQ courses in eoitware systems and analysis, organization tneory. The program also includes technical elec• software design, and management of software projects. About tives and a software engineering laboratory. four years ago we sent out questionnaires to companies near the The elective programs at different universities vary and stress university to determine the need for and feasibility of setting up a new developments in the engineering and design of software graduate software engineering program. systems. At Seattle University a sttJd~nt c~n ta~e courses on "We then proposed a curriculum that reflected industry re• "Security and Privacy" and "Distributed Computing Systems." quirements. Some companies obtained estimates of how many The "Security and Privacy" course involves encryption tech• persons would be interested in enrolling in this software pro• niques, data-base security, implementation of protection gram, and they provided seed money to cover startup costs. In schemes in operating systems and programming languages, and 1979the Board of Regents of Seattle approved the syllabus, and the legal aspects of security and privacy. appHcatioiis weie accepted for enfoiiffleni. ;;Distributed Computing Systems" presents the student with "There ts a faculty shortage at the university, and it is expected the design of architecture and software; fundamentais of data to last for a long time, because very few institutions have trained transmission, including coding, message formats, and software engineers, especially Ph.D.s," Prof. Lee says. protocols, and a survey of existing networks and future trends. "There are not many qualified software engineers who can After completing the core courses at the "'lang Institute, teach master's-Ievel courses," he observes. "Even when we find students choose three electives in such areas as operating them, the university does not have the financial resources to systems, programming languages, compiler construction, data• equal the salaries in industry-especially today, when high• base systems, distributed processing, networks, communica• paying jobsare plentiful for a qualified engineer. Few universities tions, interactive systems, CAl, graphics, management tech- have computing faciiities thai equai those in industry," niques, and design methodologies. J In the Seattle program, the faculty member must have in• The final part of the Wang curriculum is an extensive two• dustrial experience as well as academic credentials. "Some of semester project, usually a team effort, in the student's specialty our courses are taught by adjunct professors drawn from nearby area. -J.F. l'" ./ Fagenbaum-A new breed: the softwareengineer 6S this system. or electromechanical, in the auto engine machines with packaged software mod• "Also ofgreat concern isthe kind ofin• control system. ules that are coming out now will reduce formation interface for the commanding Pressure sensors, for example,measure software engineering needs in the future. officers, with the suggested steps for ac• the manifold's absolute and barometric Software packages will be built into the tions and/or countermeasures to be pressures to help determine the manifold hardware itself, so the main task left for taken. The software engineers work with vacuum pressure. "Ifthe barometric sen- the. ~~ginc:: .•\~ be desigihfig avplltations the system engineers to formulate the programs-for example, query languages hardware necessary to do the job." absolute sensor on the high side," ex• for accessing data banks." plains Peter Salamon, Ford's principal Contributing to the manpower short- v. A pivotal role design engineer in the Electronic Engine age, Mr. Jeffery says, is an attitude in in• Suppose industry tried to get along Control Department, "straightforward dustry that does not differentiate in salary without software engineers. Would it make processing would yield a negative result between a graduate engineer doing soft• a difference? Mr. Temple of Ford's for the manifold vacuum pressure. Conse• ware design and a programmer with less Research Scientific Laboratory points to quently the on-board computer receiving academic training. one small sensor in cars to demonstrate this input would put the engine ill an er• :.:; ifthere is an opening to be filled and a that it would. roneous engine start mode. In this situa• programmer around to do the job, he will In monitoring engine fuel efficiency in tion the computer must be instructed to get it, and at the same salary as the engi• cars, he notes, the electronics must process the pressure data, using higher neer," Mr. Jeffery says. "Expanded on• analyze fuel consumption at different and lower than actual readings, and there• the-job and academic training are ways to points in the system. Signals are tapped by give a true indication of the engine improve the manpower shortage, but the off a floating-arm sensor in the gasoline vacuum. This would reduce the possibility academic community must be made more tank and transmitted to an on-board com• ofhaving the engine undergo a prolonged aware of the problems in industry. What puter. work to start." we need are more programmers and less "This floating-arm sensor happens also In fault-detection systems, the software computer scientists. This training must to be subject to fluid motion and level engineer must take into account the hard• "lake: it easier for engineers to build soft• changes caused by movements ofthe auto ware and engineering specifications and ware. By making available standard soft• moving up or rolling down a hill," Mr. know how much fault can be tolerated by ware modules, it will be easier for even the Temple explains, "and these movements the engine without a shutdown. unskilled person to connect these modules have nothing to do with real gas consump• '~A software routine," Mr. Salamon together and build large software tion. The software engineer therefore has says, "must be able to distinguish between packages." to be aware of the limitations and com• false triggers, like RFI, and a real indica• £~ long-range \vay of tackling the crisis mand the microcomputer to monitor the tion that something is wrong and that an is cited by Dr. James J. Homing, principal fuel sensor and process the output data in engine fault action-such as sensor in• scientist in the Computer Science Labora• a way that can quantify what percentage ference or a warning light-is required." tory at the Xerox Palo Alto Research ofsensor response is attributed to rea! fuel Ofcourse, nowhere is the need for engi• Center in California. He sees "some hope consumption and what percentage to neers trained in software design as great as in the fact that new generations of other factors. The software must differen• in the computer industry. Designing com• students are being exposed to computers tiate temporal and inertial from actual puter systems to customer specifications is and software very early-at home, as well fuel changes." the concern of Roy Anderson, a technical as in elementary and high schools. They On another aspect of the same staffmember ofHewlett-Packard's Desk• will join the work force with attitudes and system, Mr. Temple observes, "Further• top Computer System Division in Fort backgrounds very different from those of more, the fuel gauges in these systems con• Collins, Colo. Mr. Anderson notes that the old-timeiS," Dr, Homing says. sist of bar-graph segments. though a customer has specific problems He adds that both software and hard• "The display on these gauges will be in• he wants a computer system to solve, he ware tools are important for the software correct if the mechanical inputs to them may not know exactly what kind ofhard• engineer, "'\V\; fiitisi move software engi• are cverdamped. Some kind of design is ware will do the job. The software engi• neering from being labor-intensive by in• then required that takes into account this neer works with the customer to help vesting in suitable tools. Software design operational characteristic of the gauges. design or select the hardware. The soft• is an Information-manipulation task and ~"2n llC'A ""'':lin,' ,.n",,_n+A" __ ':lI;,.IA~ .. "",..lA Software routines can be designed with ware engineer also participates in the ar• ____ _~~ &&&M&&J ~""&&&I"W"~&-w&_,-_ "VVli) overdamp algorithms to compensate for chitectural design of the system. similar to those developed for other the mechanical design of the indicators information-management profession• and thereby provide for matched signals VI. The outlook als-such as sophisticated data bases-as to be transmitted to the bar-graph What of the future of software engi• well as software-specific tools, such as segments." neering? A general shortage of specialists design verification systems and integrated Some of the other devices in auto is expected until corrective steps are taken. programming environments." engine control systems have tolerance One project manager, Seymour Jeffery of Dr. Horning believes that system band specifications, another critical situa• the TRW Defense and Space Systems reliabilitywill becomean increasingly cen... tion that the software designer must con• Group in McLean, Va., says: tral concern of software engineering. "In' sider. In programming on-board com• "In areas like traffic control and high• more and more systems, human lives and puters to process the engine control data technology processes, I can see some dif• vast sums ofmoney depend on the proper of each component, the software ficulties in satisfying software engineering design and operation of hardware and specialist must allow for the different needs, but in finance and business sectors, software systems, but since the software is tolerance ranges of each one of the com• things will get easier. I feel the latter to be vastly more complex, it will tend to be ponents, whether electrical, mechanical, true because the large number of small more error-prone." ,.

66 Fagenbaum-A new breed: the software engineer What's the Best Wau.,

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