Computergram Number 1098 (published by Apt Data Services in London) featured a story from Newsbytes that illustrates the risk of using your own name to test a computer program. Michelle Gordon, training as a police dispatcher in Bloomfield, Connecticut, was told by her instructor to use her own name as a test case to see how the computer reports outstanding "wants and warrants" against an individual. Michelle did so -- and was shocked to find out that she was wanted for passing a bad check! Back in July, she had written a $90.97 check to a clothing store, and the check had bounced. After turning herself in, she was relieved of duty -- but the police say that she should get her job back once the bill has been paid. [I notice Gary did not use HIS name. PGN]
> ... The cause reportedly may have been a breakdown in the radio > communications between a computer in Colorado Springs and an atomic > clock in Boulder. ... (Re: RISKS-8.11) I'll guess that this radio communications system is the NBS transmissions from WWV in Fort Collins (which is synchronized to Boulder). Aside from the obvious risks in designing a system the way this one (the traffic signals) was apparently done, the transmission code used by WWV is inherently risky. There is no parity check on the data in the code. (And only day of year, not year, which is another story with its own risks.) Receiving clocks must compare successive samples of the code, which is BCD-ish and has a one minute cycle, and see whether the samples are in the correct sequence. Eventually the clock decides it has correctly read the code. But if a static burst or radio fade garbles the same bit in the code for a few minutes the clock will set to the wrong time. The Heath "Most Accurate Clock" reads these transmissions and fails in this way. A couple of times a year I will see my clock confidently displaying a time which is EXACTLY 4 hours wrong or EXACTLY 20 minutes wrong.
Here are some interesting examples of hardware-software-user interaction from the British trade magazine, CONTROL AND INSTRUMENTATION, Vol 20 No 10, October 1988, pps. 57, 59: Wise After the Event by Trevor Kletz ... Computer hardware faults do occur. ... Their effects can be reduced by installing `watch-dogs.' However, an error in a watch-dog card actually caused one accident --- valves were opened at the wrong time and several tons of hot liquid were spilt [ref 1]. ...In one plant, a pump and various pipelines were used for several different duties -- for transferring methanol from a road tanker to storage, for charging it to the plant and for moving recovered methanol back from the plant. A computer set the various valves, monitored their positions and switched the transfer pump on and off. On the occasion in question, a road tanker was emptied. The pump had been started from the panel, but had been stopped by means of a local button. The next job was to transfer some methanol from storage to the plant. The computer set the valves, but as the pump had been stopped manually it had to be started manually. When the transfer was complete the PES [Programmable Electronic System --- British for computer control system - JJ] told the pump to stop, but as it had been started manually it did not stop and a spillage occured [ref 5]. ... Another incident occured on a pressure filter which was controlled by a PES. It circulated a liquor through a filter ... As more solid was deposited on the filter the pressure drop increased. To measure the pressure drop, the computer counted up the number of times that tyhe pressure of the air in the filter needed to be topped up in 15 minutes. It had been told that if less than five top-ups were needed, filtration was complete ... If more than five top-ups were needed, the liquor was circulated for a further two hours. Unfortunately a leak of compressed air into the filter occured which misled the computer into thinking that the filtration was complete. It signalled this fiction to the operator who opened the filter door --- and the entire batch, liquid and solid, was spilt. ... The system had detected that something was wrong, but the operator either ignored this warning sign or did not appreciate its significance [ref 2]. ... (In one incident) when a power failure occured on one site the computer printed a long list of alarms. The operator did not know what had caused the upset and did nothing. After a few minutes an explosion occured. Afterwards the designer admitted that he had overloaded the operator with too much information, but he asked why the individual had not assumed the worst and tripped the plant? ... (In another incident) a computer was taken off-line so that the program could be changed. At the time it was counting the revolutions on a metering pump which was feeding a batch reactor. When the computer was put back on line it continued counting where it had left off --- with the result that the reactor was overcharged. References (included in the article) 1. I Nimmo, SR Nunns, and BW Eddershaw, Lessons learned from the failure of a computer system controlling a nylon polymer plant. Safety and Reliability Society Symposium, Altrincham, UK, Nov 1987. 2. Chemical Safety Summary, Vol 56, No 221, 1985, p. 6, (Published by Chemical Industries Association, London). - Jonathan Jacky, University of Washington
>Managers see knowledge about computing only useful to engineers and >programmers. Business schools for the most part do not teach computer >literacy, nor how a non-technical manager should deal with a large software >system in his company... This is actually part of a larger problem. I recall reading an interview with a Japanese business-methods type lecturing in the US. One of the first things he asks his students to do is solve a simple quadratic equation. Many of them are baffled; most are offended. He then explains to them, as gently as possible, that one cannot do any form of optimization (of costs, production rate, whatever) without solving quadratics (at least). North American business schools, by and large, have the same preoccupations as North American businesses: mergers, acquisitions, advertising, and legal maneuvering, as opposed to making better products at lower cost. The problem, increasingly, is not that managers are ignorant of technical issues, but that they consider them unimportant. The ignorance is an effect, not a cause. Henry Spencer at U of Toronto Zoology
>From: Jerome H. Saltzer <Saltzer@LCS.MIT.Edu> >I believe that the more fundamental answer is that the pace of >improvement of hardware technology in the computer business has, for 35 >years now, simply been running faster than our ability to develop the >necessary experience to use it effectively, safely, and without big >mistakes. I don't think it's "developing" experience: it's spreading experience. The technology has given us: 1. online systems (terminals), which led to: - distributed systems - interactive human interfaces 2. speed, price, reliability, and all that. I don't think that the failures stem from our progress on Point 1. We had online systems in the 1960's. Those development projects were seen as big, expensive, hairy projects that entailed risk. Now that similar projects are cheap, the difficulty is somehow overlooked. Take, for example, the municipal system that started this debate. It was unusable because it did not integrate well into the complex environment that the projected users were already coping with. We had failures like that in the 1960's. I would blame our advanced technology, not for raising deep issues, but for putting big problems into a multitude of small hands. Don email@example.com CMU Computer Science
I can add some first hand information about losing systems. Let me tell you a story about a data collection manufacturing pacakge I stayed as far away as possible from. Background: This was a marketing intensive company. This company considers technical support people expendable. They would rather lose their experienced people because programmers/analysts coming out of school are cheaper. BTW, they hired on grade point average only. Not what you know, but what you did in school. In my experience, the two are *not* the same. It was decided we were to develop an off-the-shelf/base package which could be custom modifiable for data collection/time and attendance functions for the manufacturing environment. Because of a recent reorganization, all of the experienced project leaders and programmers *fled* the company. Our most experienced project leader (hat was left) had stated he was leaving in 6 weeks because of personal reasons. Yet the project planning and design was given to him to do. Six weeks later, he left, the project design about 30% completed. Another person (from another area in the country) was brought in to complete the design. Soon after the design was completed, *he* left the company because of a better offer elsewhere. Thus, we had no one who completely knew the entire system design. Worse, none of the programmers knew the manufacturing environment, so they couldn't spot any design errors, even if they stared them in the face. Since the reorganization made us a profit center, we now *had* to make money. This, of course, while 90% of our efforts went toward development of a product which was projected to make money in *two* years. Because we were in the red, raises were denied to certain programmers (through no fault of their own), who in turn did extremely shoddy work in the programs they put together. (And of course, left at first opportunity.) Our regional manager also declared that we would receive no new hardware, since we couldn't justify the cost because we were losing money. Thus, we didn't have the necessary hardware that this package was supposed to be running on. (Only later did marketing force our regional manager to get the equipment. Much of the equipment belonged to our certification, verification and testing site.) Because the project was losing money and behind schedule, programmers were *required* to work 45 hours per week. No compensation, no exception. Several more programmers *fled* the company. They hired part time people to fill in the losses. (Sorry, can't hire more people. Can't justify the cost!) In the scheduling, there was no provision for extensive system testing, or for the development of test scripts. More delays, more time and money lost. Because we were losing money, the company decided our district was expendable and desolved our group. We were given the option to move to a medium sized city in Southern Ohio, where their home headquarters is. *No one went*. Thus, this company had a $300K+ package, somewhat complete (about 250K to 350K lines), but far from working correctly, with NO ONE ON THE ORGINAL OR SUBSEQUENT PROJECT TEAMS LEFT IN THE COMPANY! (From the spies I have in the company, they hired a bunch of college kids straight out of school to complete the work under 2 experienced project leaders.) This post details about 40% of the problems encountered during the development. It doesn't include poor hardware design, or the fact this package is really to extensive to run on the recommended hardware. Even with all that went wrong, this company is still marketing this package today, training people how to sell it and install it. (The base package is more or less useless without modification.) I'll bet it still doesn't work today. I think I can summarized why projects fail by the following: Poor planning and quality control. By far the worst offender. How can you keep within budget and time frame if certain critical events are left out of the schedule? Poor management and company policy. This is probably the second worst offender, although I'd probably tie it for number one. Management is only interested in one thing. The bottom line. Does it make money NOW? (Apologies to those managers who aren't this way. But I'll bet if you work for a large computer corporation, and your year end bonus depends on how much your site makes, you *are* one of these.) They must also provide the necessary resources to get the project done. This includes keeping your people and treating them right. (At least until everything works! :-) Also, managers who know nothing about the computer biz or the programming environment, should be managing the sanitation engineers or the cafeteria staff. They have no business managing things they know nothing about. Poor expertise by programmers. This is not necessarily the programmers fault, but the companies fault for not providing the education. (Please note this assumes competent people! If the human resources department does their work properly, getting competent people shouldn't be a *big* problem.) Programmers should know what they're programming *for* as well as what the programs should do. Programmers should also know the project. I had enough pull and technical expertise to be involved in *other* failing projects. (Want to hear others? E-mail me, and if I have the time I'll detail others.) Keane Arase, Systems Programmer, University of Chicago Disclaimer: This company was *not* the University of Chicago!
Jerry Saltzer suggests that the trouble with software is the speed of advance in hardware; that the software developer is overwhelmed by the new function and opportunity. Else, he suggests, normal engineering discipline would suffice. I would like to suggest that it would suffice anyway if it were applied. The difficulty is that software is managed by programmers, not engineers. Programmers have no tradition of quality of their own and insist that their activity is so different from what engineers do, that engineers have nothing to teach them. Suppose that you had been an electronics engineer in 1960 but had been out of the field since. Don't you think that you would see more product complexity and risk if you re-entered today? Engineering discipline has been adequate to cope there. It would be able to cope in software too, if only it were regularly applied. I am hopeful that the use of the term "case" presages the application of more discipline in programming. I also draw hope from the entreprenurial development of software for the market, as opposed to works built for hire for a single organization. I saw a great deal of quality software at Egghead on Saturday. William Hugh Murray, Fellow, Information System Security, Ernst & Whinney 2000 National City Center Cleveland, Ohio 44114 21 Locust Avenue, Suite 2D, New Canaan, Connecticut 06840
firstname.lastname@example.org (Jim Horning) comments: > I read Bruce Karsh's diatribe with incredulity. He conjures up from thin > air a straw man to denounce. I simply cannot find any contact between the > "structured programming" that he talks about and structured programming as > it is understood in the computer science and software engineering communities. Fair enough, but he is describing an understanding which is very prevalent in the industry... Many managers from the pre-structured era understand structured programming to be just what was described: a supposed panacea. The academic community does not even know the difference. In faculty "A" of our major local university, it is understood as a suite of complexity-management tools, mostly the "mental tool" sort. In faculty "B" it is understood, if at all, as a rule-set which is supposed to produce correct programs. Any of my last three major employers contained people who took opposing views on the meaning of structured programming. What I found significant was that the people who regarded it as a tool also knew its weaknesses and knew other tools and techniques.. The people who claimed it was a panacea invariably knew no other technique for improving program quality. It sounds like Bruce worked for one of the snake-oil salesmen and did not have the opportunity to see it used by a professional or academic software engineer. And yes, I agree with him that using it as snake oil has placed us at risk. --dave (when faced with strawman, pull stuffing out) c-b
Arguments about the influence of structured programming seem slightly old fashioned to me. In the circles I travel in "object oriented" is the hot new buzzword. Jerry Schwarz
In RISKS 8.10, steve jay (email@example.com) comments > Even assuming that a 3 engined plane needs two engines to fly, > the odds of 2 engines failing on a 3 engined plane are much, much, > smaller than the odds of 1 engine failing on a 2 engined plane. this is essentially true, with the ordinary mind-bending caveats that probability theory imposes. if the probability of a single engine failing is p, then the probability of one of three engines failing is 3p (this is actually the expected value of the random variable that maps failure to one, and non-failure to zero, but it'll serve). p is a real number between zero and one, by the way. in this case, we can assume that it's closer to zero than to one. the probability of two of three engines failing is 6(p**2), since the probability of one engine failing is 3p, and the probability of one of the remaining two failing is 2p, and we multiply (since they're independent events -- the proof is sort of hairy for our purposes). all this is true, of course, as long as all the engines are working. as soon as one fails, the overall probability of failure changes. for example, the probability of two of three engines failing is 6(p**2), as above. as we're flying along, one engine fails. oops. the probability that another engine will fail is 2p, and not the 6(p**2) that seems intuitively correct. airplane engines, like coins, have no memory -- or if they do, it's the wrong kind. the risks? statements like "the odds of ... [failure] ... are much, much smaller" can be misleading. the debate here over the likelihood of failure is evidence of that -- a group of intelligent, educated people can't agree on the odds. numbers are tricky in this field, and don't always behave the way you'd expect them to. when i was studying this stuff, a friend said to me, "the first thing to do when a probability theorist asks you a question is to grab him by the throat, slam him up against the wall, and ask him, 'what do you MEAN?!?'" this is good advice. it's also a good idea to quantify things explicitly -- how *much* less likely is failure, when you add another engine? -- rather than to offer imprecise reassurance. mike olson, britton lee, inc.
I'd like to know just how applying chaos theory to a defense system shows ANY results at all about the stability of the political systems related to that system. The idea that you can mathematically prove the effects of one isolated system on the relations between two nations is absurd. The current thawing between the US and the USSR depends largely on the fact that Reagan and Gorbachev like each other. Could anybody have proved that 8 years ago? No. Phil Goetz
Please report problems with the web pages to the maintainer