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When Bugs Aren't Allowed
Coryoth writes "When you're writing software for an air traffic control system, military avionics software, or an authentication system for the NSA, the delivered code can't afford to have bugs. Praxis High Integrity Systems, who were the feature of a recent IEEE article, write exactly that kind of software. In "Correctness by Construction: A Manifesto for High-Integrity Software" developers from Praxis discuss their development method, explaining how they manage such a low defect rate, and how they can still maintain very high developer productivity rates using a more agile development method than the rigid processes usually associated with high-integrity software development."
probably helps too :P
You slashdotted stsc.hill.af.mil!
Unpretentious Sydney reviews by unqualified Sydney reviewers
Get a decent connection, the site is loading fine for me.
Nice FP attempt, I guess.
Uh... it's going to be kind of hard for the NSA to do its job without bugs, isn't it?
*rimshot*
When you're writing software for an air traffic control system, military avionics software, or an authentication system for the NSA, the delivered code can't afford to have bugs
I've been in this industry for quite some time and let me be the first to say that I wish I could repeat this sentence with a straight face.
There are a huge number of yeast infections in this county. Probably because we're downriver from the bread factory.
You just have to be l33t enough.
HAHAHA... yeah right...
I am unamerican, and proud of it!
The only method I have seen with almost perfect reliability is where the inputs and outputs are overloaded to handle any datatype and can be proven mathamatically not to crash. I guess a CS degree is still usefull.
The problem is to obtain it you need to write your own libraries and not use ansi or microsoft or any other products as you can not see or trust the source code.
If you can prove through solid design and input and output types that the program wont lose control then your set. Its buffer overflows and flawed design that has not been tested with every concievable input/output that causes most serious bugs in medical and aerospace applications.
However in practice this challenge is a little unpractical when deadlines and interopability with closed source software get in the way.
http://saveie6.com/
Can be proven safe. I wonder what subset of modern OS design could be done in such programming languages.
autopr0n is like, down and stuff.
The authors contend that there are two kinds of barriers to the adoption of best practices... First, there is often a cultural mindset or awareness barrier... Second, where the need for improvement is acknowledged and considered achievable, there are usually practical barriers to overcome such as how to acquire the necessary capability or expertise, and how to introduce the changes necessary to make the improvements.
No, the reason so much software is buggy is economics. Proprietary software vendors have to compete against other proprietary software vendors. The winners in this Darwinian struggle are the ones who release buggy software, and keep their customers on the upgrade treadmill. Users don't typically make their decisions about what software to buy based on how buggy it is, and often they can't tell how buggy it is, because they can't try it out without buying it. Some small fraction of users may go out of their way to buy less buggy software, but it's more profitable to ignore those customers.
Find free books.
It would be stupid for M$ to try to make error proof code, it is only done in cases like this because the result of a bug may mean death
Luckily, bugs are just fine if you happen to run a company that builds voting machines, such as Diebold. And if you think that elections aren't in the same category as air traffic control, I suggest you take a tour of Iraq. Elections are very important for your continued existance upon the earth.
Electric Monkey Pants
I'm not sure how much credibility can be lent to any kind of study on the software development process that does not include the open source (OSS) model. By its nature, having more eyes look over you work rather than depending on a fixed and closed system of code assurance finds and fixes bugs faster and implement new features. This is why Windows and UNIX are constantly playing catch up to the Linux platform. I remember reading a study on Google's weblog that essentialy endorsed this as a philosophical concept (that applies to much more than just code writing). I don't know who works for the NSA these days, but I would venture to say that the people who work are Google are probably collectively the brightest and wisest folks on the planet.
Linux, Firefox, and OpenOffice are some of the best software on the planet. I think is a good practical testament to the OSS philosophy.
This is the reason why I use Linux and demand that everything I purchase, consume, use, or buy uses or depends on a open source model.
Black Invention Myths
Military avionics is more risk tolerant than commercial avionics.
When you're writing software for an air traffic control system, military avionics software, or an authentication system for the NSA, the delivered code can't afford to have bugs
I've been in this industry for quite some time and let me be the first to say that I wish I could repeat this sentence with a straight face.
That was my first thought, particularly with military avionics. A few years ago they put out a hardware/software update for the ENS system (Enhanced Navigation System) which led to frequent crashing... and it took over a year for them to come out with a message saying that it was a bug and not to waste countless man hours trying to repair it.
It's sort of a new concept, though, as I'd never really seen such problems with traditional avionics systems (non glass-cockpit stuff). I've always attributed it to people being used to the behavior of MS Windows. And I'm not saying that to start a flamewar. I'm serious. Unreliable avionics systems should be unacceptable, but these days, that doesn't seem to be the case.
Ususually when the software and the phrases "life support" or "nuclear weapons" are together in the same sentence.
"I am the king of the Romans, and am superior to rules of grammar!"
-Sigismund, Holy Roman Emperor (1368-1437)
nearly unlimited funding probably helps too
The old technology axiom applies:
High Speed, Low Cost, High Quality.
Pick 2 out of 3.
The theory of relativity doesn't work right in Arkansas.
The Master Money server done by Praxis was done Fixed Price, and with a warranty that says Praxis would fix any bug discovered over the net 10 years -for free-.
How many of you would be willing to place that kind of warranty on YOUR CODE?
dave (who's tried SPARK and liked it a lot, although proofs are much harder than they should be...)
"If you can prove through solid design and input and output types that the program wont lose control then your set. Its buffer overflows and flawed design that has not been tested with every concievable input/output that causes most serious bugs in medical and aerospace applications."
I've always felt that resiliancy comes from the bottom up, and the reason our code's so brittle, is because the hardware is as well. A leaky abstraction can only be wallpapered over so much before failures start popping up all over the place.
Why can't automatic verifications systems be used for this? You start with an input set and define the output set. Run a program verification system to make sure the outputs are in the output set and don't go out of it?
The inputs or outputs could be infinite but in that case use logical constructs to verify it.
I'm not a researcher or student of this theory. So, maybe someone can illustrate to me why this wouldn't work or be applied to industry?
In the world of software development, there have come to be two defacto models.
1. Get the software out the door ASAP - quite simply, bang out code as fast as possible that meets a loosely defined specification. Then once the product is adopted, parachute help in like no tomorrow to steadily improve the product.
2. Engineer the software - not as a simple as it sounds. This requires that a specification be drawn. A plan be prepared. A team of solid engineers formed and lead by a competent manager. Then, throughout the entire development cycle, test and debug code.
My company does the latter and to do date we have retained 100% of our customers. I'm shocked by the number of developers that approach our company for jobs that don't have the first clue about how to even write a test harness, let alone do any real debugging. Then again, they don't teach much of that stuff in school and it seems that unless your role was specifically in testing at a previous job, that you're not going to have too much experience in that area. Its economics and marketing that put the bugs in software, not computer science.
It's not hard to produce nearly-bugless code when you have both the budget to do proper quality control, and the incentive to do so.
The reason why Windows is not bugless is that they have the budget to properly debug it... but little incentive to do so before launch. The customers will purchase it anyway and gratefully accept bug fixes after the fact. Airports or the military who bought faulty mission-critical software would not be so forgiving.
Freedom: "I won't!"
The main obstacle in writing a decent code is usualy the management - their frequent changes of mind (about what they want - which is usualy different from what is helpful to the users) and their "good enough" and "legacy first" attitude. Overreaching ambition is another problem - one needs to limit himself to fewer things to do them well - and the management pressures usualy run in oposite direction. (Salesmanship bullshit never helps, especialy if it starts to influence the direction of your project.)
I doubt that we will ever figure out - and I suspect that even if we did figure out we couldn't do much about it
30 LOC - That's 30 lines of code a day. Unlimited budget combined with enough time and resources to do the job right.
That's why systems and platforms like these are written in a tried and true language like JOVIAL.
-- SKYKING, SKYKING, DO NOT ANSWER.
I count less than 400k source code lines among their examples ("SLOC"). Collectively, this is at least an order of magnitude (maybe two or more actually, I don't know) shorter than the really big projects out there. So I guess I have two questions. First, is this rate really good given the size of the projects described? And second, for the huge projects, what sort of bug rates are theoretically achievable?
control structures != Turing complete. You can have loops as long as they have constant maximum bounds. Whatever it happens to be that you mean when you say "Nand is Turing complete" it makes no sense when you actually typed it. "turing-complete (for arithmetic)." makes no sense at all. WTF? Someone failed CS 315.
autopr0n is like, down and stuff.
I think Microsoft should hire some Praxis employees...
unlimited risk can be an incentive too.
Professor Middlebrook at caltech was an innovator in an unusual field. Sattelite electronics. Since no repairman was coming they wanted robust electronics. He desigined circuits in which any component could fail as an open or a short and it would remain in spec. You know that's a remarkable achievement if you've ever desinged a circuit before. Notably you can't really do this using SPICE. Speice will tell you what comething does but not how to design it. To do that you need a really good sense of approximations of the mathematical formula a circuit represents to see which components are coupled in which terms. And you need one more trick. The ability to put in a new element bridging any two points and quickly see how it affects the cicuit in the presence of feedback. To do that he invented the "extra element theorem" which allows you to compute this in analytic form from just a couple simple calculations. They still don't teach this in stardard courses yet. You can find it in Vorperians text book, but that's it. If you want to learn it you gotta either go to the original research articles from the 70s.
Some drink at the fountain of knowledge. Others just gargle.
I was at an X windows technical conference many years ago when someone gave a presentation on X with Ada. When the speaker mentioned that it was for an air traffic control application, there was a sharp intake of breath all around the audience, most of whom had flown in for the meeting.
It still doesn't show anything about the quality of the code. I've been on teams that built great systems (like the ones that supply those great maps in google maps) under mil-spec/SEI standards, but the performance and extensibility of that system really was lacking (and those requirements were in the use cases).
Still, knowing some of those guys, they do some quality work.
So Windows is never used in any life or death situations? That is hard to believe.
I stopped reading when I saw that they equate productivity with lines of code per day...
Code without bugs. Well I never...
Register the editry.
Not that anyone else rtfa, but defects per line of code seems like a bad measurement of how high quality your code is. More lines != more productive.
Then again I've been suspicious of hyped press releases claiming that the government has super efficient ways to write superior code, ever since that mars orbiter crashed due to mistaken units conversion....
"TV is great! Every New Year's I make a resolution to watch more TV." - Ann Coulter
In school, this article was required reading for our class. It addresses the same topic as TFA.
The essential point being there is a trade-off between quality and quantity and each organization/project needs to decide how far they want to lean in either direction.
Give an example.
Only the part about 50% price increase.
TFA cites a particular NSA biometric identification program which has "0.00" errors per KSLOC.
Now, this got me thinking. It is completely possible for a biometric identification program to identify two different individuals as the same person (like identical twins), or for it give a false negative identification (dirt on a lense, etc). Is this a bug? The code is perfect: no memory leaks, the thing never halts or crashes or segfaults, all the functions return what they should given what they are.
I think the popular definition of "bug" tends to catch too many fish, in that it seems to include all the behaviors a computer has when the user "didn't expect that output," what a more technical person might call a "misfeature." TFA outlines a working pattern to avoid coding errors, not user interface burps -- like for example, giving a yes/no result for a biometric scan, when in fact it's a question of probabilities and the operator might need to know the probabilities. Such omissions (the end user would call this a 'bug'), are solved thru good QA and beta-testing, but TFA makes no mention of either of these things, and seems to think that good coding is the art of making sure you never dereference a pointer after free()'ing it. It does mention formal specification, but that is only half the job, and alot of problems only become clear when you have the running app infront of you.
Discussion of TFA has its place, but it promises zero-defect programming, which is impossible without working with the users.
Don't blame me, I voted for Baltar.
If someone sent a copy of this to Micro$oft? Would any of them read or comprehend it? It could make a difference in the version after Vista.
Oddly enough it would make perfect sense to some people at MS. The Singularity OS project from MS research uses a lot of the same ideas in development methodology and formalism. Whether Singularity will ever make it out of MS research, or simply remain a curious little side project, is of course an interesting and quite open question. Only time will tell.
For other OSs developed in a similar mold, try Coyotos which, while still getting seriously underway, looks quite promising indeed when it comes to secure and robust OSs.
Jedidiah.
Craft Beer Programming T-shirts
Considering the millions of lines of code in Windows XP, I suspect that Microsoft's error rates are not a whole lot higher (and may even be significantly lower) than their target of 0.1 errors/ KLOC. The situtations aren't entirely comparable, though. Windows is written primarily in C and C++, languages that are not well suited to extensive static modelling and analysis. Also, Windows XP is a third generation product, and has been extensively field tested through previous generations and customer betas, options that are not available to a product that must be almost bug free for the very first release.
Who was it that said a test system can never be perfect because it must be at least as complex, or more complex than the system being tested?
"No matter where you go, there you are." -- Buckaroo Banzai
Not by anyone intelligent. Anyone that uses a M$ product in a mission critical area is courting catastrophe.
Professional Politicians are not the solution, they ARE the problem.
in practicallity, it does.
/.ers, break it down to an unrealistic and non-practical point. Making your arguement little more then shaky ramblings.
You ned to keep the lines of code measurment in contexts with other issues. Like design, and all the other usual suspects. But that applies to ANY metric you use.
Also, this may help Perl programmers to write script that only does ONE thing per line!
also, just:
assert(1);
won't compile.
Of course you, like many ignorant
The Kruger Dunning explains most post on
Or so they say. I've spent many years in this industry too. Even the best teams I worked with had lots of bugs - lots! Every project has defects - every one. Government contractors sell billable hours - not software. Praxis has marketing good enough to sell their billable hours for more than the competition. Good job!
The site is slashdotted at the moment, so I can't read the article.
A good example of people writing complex but bug-free software under time pressure is the annual ICFP Programming Contest. This contest runs over three days, the tasks are complex enough that you usually need to write 2000 - 3000 lines of code to tackle them, and the very first thing the judges do is to throw corner-cases at the programs in an effort to find bugs. Any incorrect result or crash and you're out of the contest instantly. After that, the winner is generally the highest-performing of the correct programs.
Each year, up to 90% of the entries are eliminated in the first round due to bugs, usually including almost all the programs written in C and C++ and Java. Ocassionally, a C++ program will get through and may do well -- even win, as in 2003 when you didn't actually submit your program but ran it yourself (so it never saw data you didn't have a chance to fix it for). But most of the prize getters year after year seem to use one of three not-yet-mainstream languages:
- Dylan
- Haskell
- OCaml
You can argue about why, and about which of these three is the best, or which of them is more usable by mortals (I pick Dylan), but all of them are very expressive languages with uncluttered code (compared to C++ or Java), completely type-safe, produce fast compiled code, and use garbage collection.
Thanks for stating the obvious. Any Software Engineer with half a soul has the same guidelines.
My motto is: "If you strive for perfection, then the end result will always be better than settling for mediocrity."
"No matter where you go, there you are." -- Buckaroo Banzai
I have some beef to pick with the article: 1. It alleges that CMM5 organizations have about 1 defect/KLOC. Having worked and knowing such organizations, I can anecdotally confirm numbers like these are fiction. CMM5 certification has more to do with greasing palms rather than any absolute defect measurement. 2. A defect rate of 0.04bugs/KLOC is not zero bugs/KLOC. The difference is infinite in magnitude if that single bug is -- kills the user. 3. Low defect rates are more often a product of poor testing, not superior development.
FTA: "For example, C, C++, Structured Query Language (SQL), Ada '83 and Ada '95 have been used. However, such languages are intrinsically unsuitable for deep static analysis and are only ever used for the non-critical parts of the implementation."
What language do they use?
Hey, good point... bring out a case where HUMAN error caused something to go boom. I think if you read the article, you'll see they mean software only, human error is still up to the error between the chair and keyboard.
Want to find other gamers to play board and role playing game
The truth of the matter is, no matter how hard we try, very few people were actually "meant" to code. People don't think like machines. And the few that do are probably working for companies that do high-integrity software that human lives depend on (and Google of course). I think very few people can write complicated bug-free code, and most of the ones that "do" get lucky and get their bugs caught during testing (and don't create more bugs fixing it). Companies are in a hurry. They don't like to devote too much time to QA. Since bugs are an inevitable part of complicated software, it's the companies decision as to how many estimated unknown bugs is considered "stable enough for release". Be it a text interface or some amazing simulation VR system, the more user interactivity and freedom they are given, the harder it will be to create bug-free software. When talking with non-technical folks when they bitch about their computer freaking out, I just tell them "It's easy to make something do what you want it to do. Making it not do what you don't want it to do is a lot more complex". I think the key to minimizing bugs other then proper testing is dividing the program up into as many reasonable simple parts as possible (Yes, I'm a fan of OOP) with strict guidelines for interaction outside of the class/method, and have the overall interactions of each class evaluated by a reasonable number of people so possible problems can be spotted. And I am done ranting.
In undeveloped countries, the consumer controls the market. In capitalist America, the market controls you.
Summary of the article: "We're great. Trust us. Hire us. Pay us lots of money--it may look expensive, but we promise it will be cheaper in the long run. Really."
Comment removed based on user account deletion
"Yes, yes, open source projects fix bugs for free. The point is that they can afford to do that, because they have so many volunteers to do the bug-fixes."
The Praxis approach starts with the mindset that bugs are bad and shouldn't leave the room. Open-source has much looser requirements. Bugs can be released with the attitude that "a thousand eyes" will catch the mistake. Also unmentioned by OSS advocates is the problems caused during the duration of the bug being unfixed, till those eyes catch it (which isn't guarenteed). Also OSS isn't guarenteed (read the disclaimer, and remember the "/." story awhile back about programmers being held liable for problems with their code. Read the responses) while Praxis is. And last Praxis plays in a field that OSS doesn't. (mission/life critical)
Personally I think that we just accept bugs nowadays , I use some very buggy software when laying out PCBs and have had to find several 'work arounds' to get the finished project. I mean who complains about the amount of updates you need for Windows , you just accept that if your computer crashes you re-boot , CTRL-ALT-DEL gets used often when it just hangs. I think that if we keep on accept it that software will have bugs it will only get worse.
I say we take off and Nuke the site from Orbit, It's the only way to be sure.
Same with Linux, or any other system not developed under stringent requirements.
Rex is 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0
Actually, there was a case (in 2000, I believe) where a destroyer (the ship, not robot) was running a version of windows, got a divide by zero error, and the ship's systems all crashed. It was dead in the water for a few hours.
Yes, found a wiki:
Note, it was running Windows NT 4.0. So yes, in military warships we even us Windows. I also believe that Britain's newest destroyer runs on a version, but I forget which, as I read it a while back.
Want to find other gamers to play board and role playing game
The end result - In a year, no one will remember that you were 6 months late - make a buggy release and in a year EVERYONE will remember the buggy release.
Why I always have time to do it over, and never the time to do it right in the first place
I have mod points and I am not afraid to use them
...they're undocumented features.
I could design and implement a bulletproof voting box over a couple of weeks for probably around $10,000 tops, dropping that to $2000 or so in volume production with a healthy profit included. Diebold seems to have problems with this simple task. They also make ATMs, and I bet the banks don't put up with that kind of shit. The only reasonable explanation is intentional malfeasance.
BFD.
How does that compare to the rest of the world?
3 days ago I was given insufficient documentation and no testing information for a new invoice process. I told my Project Manager that the specs were not sufficient, I was told to "Do what you can". Over the last 3 days I have wasted a few hours waiting for people to get out of meetings so I could ask them piddly questions about the new process, double tracking over code as new requirements were "discovered", and dealing with a 3rd party database that isn't designed to handle what the users think they want.
Today I sent 2 sample invoices up the the leasing department. They didn't understand why certain items where showing up twice (due to multiple transactions for an asset on an invoice), so they sent down two test cases. I ran both test cases and they both failed to pass the original (vague) business rules I was given.
End result, I wasted 3 days developing an Invioce no one can use because no one could be bothered to come up with a requirements doc.
-Rick
"Most people in the U.S. wouldn't know they live in a tyrannical state if it walked up and grabbed their junk." - MyFirs
That shit really works good.
Most customers are business people. Most business people are idiots. Therefore: most customers are idiots. Given that fact, the only thing that can save you from spending months cranking out a specification/contract that will never be fully read, or pounding out garbage that's a nightmare to maintain is to go Agile. I favor XP, but anything where the process includes delivering the most important features using Test Driven Development, small iterations, acceptance tests, etc. will work. Besides, by the time you get something working in front of them, they'll "reprioritize" to the newest Shiny-Thing and you'll be glad not to have produced the 1/2 ream of dead tree UML (that was out of date on day two of "coding"), or the rat's nest in your source tree (mostly written by the guy who quit two monts ago after his wife divorced him for never being home).
*** Sigs are a stupid waste of bandwidth.
This is very interesting and encouraging work. One possible difficulty I would like to point to is that their approach requires specialized skills that most developers do not have. Also, as pointed out by one comment here on Slashdot, one often has to access third party libraries that are not fully reliable. Finally, in a business environment, one will have difficulty selling a highly academic methodology that requires a radically different skill set (e.g., formal analysis, predicate calculus, etc.) than what is available. Their work may be very effective in high-assurance settings that can be very careful about assembling the right team and defining the right process. I can see it being used in military and avionics applications, as they say. For business application environments, it is probably more practical to take a "best practices" approach, and tackle the problem from a methodological perspective, by adding assurance steps to existing maintstream methodologies, rather than by requiring an enrirely different approach for writing requirements. I have just written a book about this by the way. See "High-Assurance Design" on Amazon, or look for the article by myself and Scott Ambler which should be out soon. - Cliff
Wouldn't UML help with engineering? It's designed of this purpose. You can UML anything, and reports have it that UML makes it easier to find bugs, and make deadlines.
You are completely missing the point of CbyC development. One of the fundamentals is that these apps are RESISTANT TO CHANGE. So yes, MS could make a much more solid OS, IF you ran their, and only their proprietary hardware (as Apple used to/still does), only used the pre-installed applications in the exact manor they were designed to be used, and never drempt of changing anything.
When you are talking about an air traffic control system, you can set a very specific set of requirements. The Air Traffic Control system will never have to open an Excel worksheet, or run Quake 4, or be compatible with hundreds of other vendors tools. The Air Traffic Control system will never have to deal with someone swaping graphics cards and updating drivers. It doesn't have to worry about spyware and root kits. It doesn't have to worry about internet access.
If you want to rag on MS, go for it, but don't think CbyC is the answer. It would only result in an OS that you wouldn't want to use. (As a consumer it would be worthless, but it could be great for imbedded systems)
-Rick
"Most people in the U.S. wouldn't know they live in a tyrannical state if it walked up and grabbed their junk." - MyFirs
Not anyone like, say, the US Navy, for example:
, 13758,00.html
s ID=2275
http://wired-vig.wired.com/news/technology/0,1282
Or air traffic controllers:
http://www.techworld.com/opsys/news/index.cfm?New
Or nuclear power plants:
http://www.securityfocus.com/news/6767
Regardless of how you rate the intelligence of the parties involved in these little incidents I think you'll find that Windows is very often deployed in mission critical areas.
And yes, often with catastrophic consequences. >)
Have fun,
Nathan 'Nato' Uno
http://web.unos.net/
Bugs are allowed, but software "should" be tested and patched before release.
1 bug per 10K lines of code is pretty good, but by no means remarkable. The teams which actually write avionics software for jets routinely reach levels of no more than 3 defects per 1M lines of code.
The Coyotos project attempts to implement a full OS that can be mathematically proven safe and secure. It's actually quite a fascinating project; reading the mailing lists and watching BitC and Coyotos develop feels a bit like what it must've felt like to watch UNIX and C grow up in the 70s.
It's like all the suits who love to say "failure is not an option," but then we see the occasional failure, but people still say "failure is not an option" because it's the attitude they're trying to convey, not the reality. The right attitude will bring about the right reality, or so management would have you believe.
I knew a guy who worked for Nav Canada, the company that does the computer systems for air traffic control in Canada. He was responsible for part of the system covering the arctic. He said one time that for a certain day of they year he had considered programming in a "glitch" moving through that air space. But decided against it. Wise choice. Would have been pretty funny though, as long as no one got killed over it.
--Julian
Re-read the article you linked to on the Navy. The Aegis software is from Lockheed Martin, not M$. The Navy is more than capable of screwing up and making itself look worse in a half-assed cover-up, but they don't use M$ products for system controls.
If you want a better comparison, go to the bank. Windows everywhere in the floor, except at the teller stations. Unix or RPG are there with all the servers on Unix or AIX. M$ is fine for typing letters, but never for actually handling accounts or real money.
Professional Politicians are not the solution, they ARE the problem.
I RTFA to the point where they started putting restrictions on languages of choice and then I stopped. I don't disagree. I just realize the article applies less to my work than I thought. My software doesn't need that level of perfection early in the process. However as per usual, some good stuff to take away from the article at a general level and apply to work. Of course the general stuff we've all heard before. It's just applying it that's the hard part at times!
Just to add to mix, the specification "z notation" mentioned in the article can be found here
Hey, I'm just saying... if Star Trek has done just about every planet in the known sky and the one you picked blew up spectacularly in a feature film... that might not be a good omen.
Yeah, it is Santa... or a Russian ICBM?
Mmost programmers don't have any source of pride to recheck their work. They just write the crap and assume it will work. A long time back I needed to write a machine language checkerboard memory test for a Honeywell H316 minicomputer. I revised the program several times after inspecting my code and managed to get it to run perfect the first time in only 23 lines of code. Check your code many times and your software won't have problems.
The *software* might be from Lockheed Martin, but the Navy deployed it, including the Microsoft components delivered by Lockheed Martin, in a production environment. The Navy deployed it, the Navy's ship stopped working (which I think is part of the definition of "system controls" - controls which determine whether or not the ship is working). No sense in blaming Lockheed Martin for that one...
v a-general-features.htm
And if you think Windows isn't used in banking ATMs, which handle both accounts and "real" money, perhaps you should consult with Google:
http://www.universal.com.sa/english/products-opte
http://msnbc.msn.com/id/3675891/
(and there are many others...)
Have fun,
Nathan 'Nato' Uno
http://web.unos.net/
I'll see your compiler error and raise you a thousand pointless #defines!
I will give you that the article isn't clear that Lockheed Martin's Aegis system deploys Microsoft components. However, I used to work for Lockheed Martin, specifically *on* the Aegis system components, and I probably shouldn't comment further.
, 00.html
So instead I offer this link to the US Navy deploying Microsoft for critical control systems:
http://www.wired.com/news/technology/0,1282,13987
Trust me, they do it.
Have fun,
Nathan 'Nato' Uno
http://web.unos.net/
Not a single trek joke yet, the geek level is really dropping around here!
People who think they know everything really piss off those of us that actually do.
Can it really use its phased array to overload inbound missile electronics?
"No, the reason so much software is buggy is economics. "
Nope, according to Alan Cooper of "The Inmates are running the Asylum" fame. It's the "geeks" (Homo Logicus). Chapter seven covers this group.
I am the CEO of Assplode networks....we make your networks Assplode! To achieve our higher than industry results we only hire the most experienced goatse.cx assploder's! Please post our a link to our "brown paper" citing how we were able to make even the most trivial networks Assplode!
Am I the only one amused by Praxis exploding due to unsafe practices?
/chuckles to self
-volve
One time I was developing a system used by attorneys to manage revenue contracts for a major networking company. They would threaten to terminate my contract if there was a single bug or say something like "I don't think he's taking his job seriously". My manager described the legal team as "unforgiving".
-c0d3r-
I've been a controller for 13 years and have worked in the automation end of things for almost 4 years now. There is NO SUCH THING as bug-free Air Traffic Control software. The best we can hope for is heterogenous redundancy and non-simultaneous failures. Some engineers seriously think they could replace all those controllers with an intelligent algorhythm. What really scares me is that the more they try, the less engaged the people become and the harder it is for them to fall back to manual procedures when the worst happens.
Everyone used to laugh at how Windows NT could only run for 34 days before it needed a reboot. Some of our systems can't run HALF that long without needing a server switch-over or complete cold-start.
That's how much of the system you control. By system I mean the entire channel, including the hardware, software, input, etc. It's much easier to engineer low defect software when you control all of that. For example if you are developing something that runs only on one particular version of one kind of embedded device, and can only have input given to it in a certian way, and you can gaurentee that it is the only thing running at a given time, and so on.
Much harder if you are making something that has to run on a massive set of arbitrary hardware that can have any number of other, quite possibly buggy, apps running and that can recieve all kinds of bad input through all kinds of different channels.
That's part of the problem I see is that people look at systems that are engineered and controlled by one company, and then think that software that runs on comoddity hardware should be as reliable as something where everything is carefully controlled.
think of the bugs!!! Seriously where would most of us geek types be without the bugs. What would you blame the missed deadline on then, huh?
So, if this toolset and methodology are so good, I have to wonder why it does not get more widespread use? According to their info, it is developed in the 70's and 80's, so that's not new. And why are softwares so buggy and have such a lousy reputation anyway? Not to start a flamewar, but let's just list a few possible "reaons" here:
.... so, are software vendors a bunch of irresponsible kids that need constant monitoring?
1. Why aren't schools teaching this methodoly thoroughly? Why aren't this toolset and programming language taught in school by default? I learned a bit of Ada at school, but that's only part of a comparison between programming language design. So, are schools to be blamed? Or those profs don't know better? Why aren't proper engineering methodologies emphasized?
2. Someone developed a nice methodology, with a nice toolset and programming language, and got greedy and made it too expensive to acquire. Other tools are good enough, and the resulting softwares are acceptable to the market, so, this nice thing never got widespread use.
3. Programmers are asked to do the impossible. We (I include myself here) had to work with customers who don't know what they want, only give very fuzzy requirements (Praxis's customers, from their list, are different kind of animals, and they probably know better than most of the customers we had to work with), and even if we lay out the whole detailed plan in front of them, they still don't know what they want. They will agree to the plan, sign and approve it, and until you have completed the whole system according to the plan, they would ask to redo the whole thing. If a customer dares to ask a civil engineer to add 2 more stories between the 3rd and 4th floor after the custom-built building is finished, guess what would the civil engineer say? Programmers are asked to do this all the time (I know I have been asked to), so are customers to blame? You can't get the system done properly if requirements are shifting all the time.
4. Programmers are a bunch of bozos who know shit about proper engineering. Yeah, I can take the blame, I've been programming for over a decade, and I know how programmers work: methodologies are for pimps! If a bridge engineer can't tell or prove how much load the bridge can take, I'm sure people would tell him/her that s/he has no business in building bridge.
5. Customers of packaged softwares would buy a buggy software to save one buck anyway, why would vendors put extra efforts and costs to make it better? Look at the market, a lot of good softwares didn't survive, and sometimes, the worst of the line prospoered (no naming here!). So people get what they asked for.
6. Customers (even custom-built projects customers) are a bunch of cheap folks, they would go to the least priced, no matter what. Praxis's customers are willing to pay 50% more for quality work, how many of your customers are willing to? We are willing to fix our bugs, free of charge, for the first 10 years too, if our customers are willing to pay 50% than the market rate for quality work. But so far, I've never met one such customer yet. Granted, I don't work in the defense industry. So, don't blame us for lousy work, if customers try to squeeze out every single buck out of it. And in China (and some other countries too), you have to pay a huge amount for kickback too, sometimes, as high as 80% of the project's budget.
7. Software vendors are a bunch of greedy bastards, they put buggy softwares on the market, without having to accept any responsibility (just read your EULA!). Industry problem or government problem? Not enough regulations (for safety, for useability, etc)? Other industries seem to do ok, e.g. medical, civil,
8. The indsutry is developing too fast, people are chasing the coolest, hippiest, most buzzword-sounding technologies. No one gives a shit about "real engineering". And there are simply too much to learn too, in how many industries can you say people are required to master that much technologi
The Praxis that blew up in Star Trek VI was a Klingon moon.
Even though I haven't seen the movie in 10 years, I still remember that. Sad, huh?
"If you want to learn it you gotta either go to the original research articles from the 70s."
r ial/nEET.pdf
r ial/slidesAppC.pdf
http://www.edn.com/archives/1995/080395/16df4.htm
"The extra element theorem is used for analog circuitry. The gist of it is that you remove the reactive elements ( or dependant sources ) from a circuit and then put them back in through a process of correction factors."
[n-extra element theorem]
http://ece-www.colorado.edu/~ecen5807/course_mate
[Middlebrook's extra element theorem]
http://ece-www.colorado.edu/~ecen5807/course_mate
In the end, software companies are in it for the profits. They have no lemon laws to respect, they have no trades description act to obey, no ombudsmen to answer to, no consumer rights groups to speak of, no Government-imposed standards certification and virtually no significant competition. Customers are often infinitely patient and completely ignorant of what they should be getting - the machines are like Gods and the software salesmen are their High Priests. To question is to be smote.
Were standards to be mandated - perhaps formal methods for design, OR quality certification of the end result, you would see no real impact on net software costs. Starting costs would go up, but long-term costs would go down.
Nor would you see any serious impact on variety - if anything, there is a greater range of car manufacturer and design today than there was in the 50s and 60s when cars had the unnerving habit of exploding for no apparent reason.
What you'd see is a decline in stupid bugs, a decline in bloat, an increase in modularity, possibly a reduction in latency and a move from upgrades to fix things that SHOULD have worked in the first place to enhancing things that can be relied upon to CONTINUE working fter the patches.
Money would not be made by selling the same product with a different set of defects to the same market, money would be made by always going beyond last year's horizons. The same way most manufacturers, from cars to camping gear to remote control aircraft to air conditioning units to microwave ovens to home stereo manufacturers have all been doing - very successfully - for a very long time.
The IT industry isn't going to change in the foreseeable future, the only way we'll see change in our lifetimes is if it is imposed on the Pointy Haired Bosses. We could easily see 99.9% reliable software, with no additional cost, in our homes in a year, with the lack of constant fixes actually saving money. And that's why it won't happen. Not because the IT corporations are mean, thuggish and ogreish - they are, it just isn't way it won't happen.
It won't happen because they're geared both towards the profit motive and towards the outdated notion that the market is tiny. (That last part was true - in the 1950s, when entire countries might have three or four computers in total, operating in two, maybe three different capacities. You can understand a desire to go after the after-sales service, when there simply isn't anything else left to do.)
Today, Microsoft's Windows resides on 98% of the desktop computers, but because of the support system needed to run the damn things, 98% of the world's population didn't have significant access to one. Ok, putrid green is a lousy colour, but the idea of clockwork near-indestructible laptops that - in theory - could be built to weigh 5 lbs or less and run high-end, intensive applications is beginning to filter through to the brain-dead we call politicians.
You think someone in the middle of Ethiopia who is fluent only in their native tounge is going to want to pay for telephone technical support from someone in India, in order to figure out why their machine keeps locking up?
When computing is truly available to the masses (ie: when even a long-forgotten South American tribe can reasonably gain access to one), the ONLY way it can be remotely practical is if said South American can look forward to a reliable, usable, practical experience where all usage can be inferred from first principles, and where NO software service calls are required to get things to work, ONLY required to get more things for working with.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
Dylan Programming Language
/stupid slashcode wouldn't let me post them without the " Programming Language" part
Haskell Programming Language
OCaml Programming Language
Nevertheless, regardless, and bethatasitmay, I was siding with the person who expressed the opinion which got modded flamebait. Um, yes, bork bork, I know that an air-traffic-control system would make a poor desktop OS, along with other mission-critical applications such as power-plant-control systems at the plant I used to work at. But, yeah, surely *any* programmer making a desktop OS would at least have a thing or two to learn from the mere *reading* of the specifications from such projects, and perhaps it might even inspire them to make their desktop a more hardy place, maybe even through porting an idea inspired by the mission-critical system, leading to some of that innovation we're all hoping for (even us non-Winodws-users) in Vista.
Why do posts that start with "You're missing the point!!!" always start out in left field and head for the parking lot?
http://en.wikipedia.org/wiki/IEFBR14
/dev/null. It returns immediately when called. It had four or five bug reports filed against it.
IEFBR14 is sort of an executable version of
IBM could of course write a defect-free return statement. All the bugs were requirements drift that Praxis could not have prevented.
This was done as a test of a cheap autopilot. It would never be used in anything but a test. The Captains career is over if his ship collides with anything. He wants an alert human helmsman.
USN Sub sailor 1976 - 1980
Professional Politicians are not the solution, they ARE the problem.
The qualities of an ideal test is a framework similar to ACID for databases and INVEST for user stories. It describes six verifiable qualities that a test should have. On a related note, this article doesn't make me really that excited. I've been using test driven development with JUnit and NUnit to deliver tens of thousands of lines of code into production with similar defect rates (about two defects found over the course of several years of code being in production). I maintained good productivity rates, delivered code into QA with no defects found, into pre-production with no defects found and finally into production where defects were found only after a great deal of time in operation. The code was not simple either: it was asynchronous, guaranteed delivery, multi-threaded messaging code for enterprise systems. Developers who don't do TDD should be paid about 1/4 as much as developers who do, IMNSHO.
Helping with organizational effectiveness is our job.
Bwah-hah-hah-ha-ha!
Havoc Video
The sentance you refer to compared M$ 3year cycle with crash problems to the Navy's 5 year cycle with more testing, which is when this happened. The Lockheed Martin software was in the test phase, not deployed operationaly.
Professional Politicians are not the solution, they ARE the problem.
For you I'd recommend GME (read the tutorials first) and finish up with Martin Fowler's Language Workbenches
This article couldn't have been more coincidental to my current project: I've been re-reading James Martin's books, "Application Development without Programmers" and "System Design from Provably Correct Constructs", with the goal of selecting a method to program mechanical devices.
Martin's thesis, and remember this was back in the 70's and early 80's, was that the program should be generated from a specification of WHAT the program was to do, rather than trying to translate faulty specifications into code telling the computer HOW to do it. (Trust me, that poor sentence does not come close to describing the clarity of purpose in Martin's books.) Martin proposes that a specification language can be rigid enough to generate provably correct programs by combining a few provably correct structures into provably correct libraries from which to derive provably correct systems.
The definition of the time, HOS (for Higher-Order Software) was actually used by a company called HOS, Inc.(!), and apparently worked pretty well. Many of the constructive ideas were included in OOP and UML, but ideally, if I understand the concept properly, it would be equivalent to generating software mostly from Use-Case analysis. There are similar approaches in MDD and MDA methodologies. I wonder what ever became of the HOS,Inc. and the HOS methods? It looks like they had a handle on round-trip software engineering in the 80's.
OK, why would this be a good thing? Well, for one thing, computational/programmable devices are prolifierating at a tremendous rate, and while we can engineer a new device in 3 to 6 months, the programs for the device take 18 months to 3 years (if they are finished at all). Hardware development has greatly outpaced software development, by some estimations a 100x diference in capacity...yet they are built on the same fundamental logic!
The best argument, IMO, is that since larger systems are logarithmically more complex, and since it is impossible to completely test even intermediately complex systems, it will require provably correct modules or objects to produce dependable systems. If the code is generated from provably correct components, then the system only has to be tested for correct outputs.
Furthermore, code generated from provably correct components can allow machinery and devices to adapt in a provably correct way by rigorously specifying the outputs and changes to the outputs.
Praxis is on a roll. The methodology employed is probably more important than the genius of the programmers. It should get better,though. The most mediocre Engineer today can produce better devices than the brilliant Engineers of 30 years ago using tested off-the-shelf components. IMO, this the direction programming should be taking.
"The mind works quicker than you think!"
In reality, my system is a hell of a lot more effective. Show the bugs a picture of the SPARK product manager and bugs are so utterly freaked out, that they run for the hills rather than residing in the code.
BeauHD. Worst editor since kdawson.
But seriously, that's cool. Any 'net resources on this for us software types who'd like to think we can solder two wires together without burning down the house?
They're allowed to have one!
Congratulations to slashdot for actually addressing the issue of safety-critical software. Folks, this is a completely different world than, say, the world of games or google searches -- where 80% of the output is *expected* to be crap. And the right language for the job is Ada.
I watch Brit Hume on Fox News
I was told that NAND is Turing-complete by someone smarter than I. I realized that NAND itself has no program flow, thus it can't be turing complete all by itself.
It is possible to build any logic circuit using nothing but NAND gates. That includes processors and even entire computers.
It is also true that area and speed are generally interchangeable in logic design. One can do some rather amazing tasks with really small circuits so long as your are not in any hurry to see the results.
However, I submit that the smallest "touring complete" processor is at least 3 NAND gates.
2 nand gates = 1 SR flop, the smallest storage element buildable from NAND
1 nand for computation.
With only 1 bit, it's well short of the infinite storage requirement. But then, all constructable devices fail that one.
Doesn't the underlying operating also play a big part in the reliability of the software? Even if your code is correct, can you say the same for what you run the code on, or what you compiled/interpreted it with? Then there is the hardware.
It reminds me of many medical devices that have software running on Windows internally. I remember having LASIK done and the device looked like it was run by a PC with a Windows app. I did not turn out blind.
Since they also give SLOC and whole-lifecycle-SLOC/day metrics, we can calculate the "sizes" of the projects...
CDIS: 42.5 person years
SHOLIS: 10.5 person years
MULTOS CA: 9.8 person years
A: 9.7 person years
NSA: 8.6 person months
So we're not talking about "tiny" projects here...
I've hear stories about other mission critical software that keeps failing but speaking from experience the mission critical military air traffic controle system I managed was in no way bug free on the software side.
The most important decisions in a society are made now in what are essentially advertising wars (campaigns). The most difficult issues become 10 second soundbites. We need to get rid of elections above a regional level. Seriously. People don't know enough to even understand the issues, let alone choose solutions.
As a computer science student, I would like to know why we aren't taught this in school. My professors have told me that software verification is a nearly impossible task which is too complicated for any real system, but this article claims otherwise. Why aren't we being taught that we should be responsible for writing reliable code and how to do it? Why haven't I heard of Z or other methods for writing provable specifications? My professors can't even write a decent specifcation. And supposedly this is one of the best Computer Science programs in the US. If students aren't even taught that it is possible to write near bug free software, it's no wonder that software is so unreliable.
>When you're writing software for an air traffic control system, military avionics software,
>or an authentication system for the NSA, the delivered code can't afford to have bugs
Considering the exploits of sheik Osama bin Laden, the firm certainly didn't do its job very well.
or maybe
Fighting bugs is futile, as humans remain the weakest part of the system. Western people lack strong morals, become lazy because of their advanced environment and they are easily corrupted by money. Computers cannot stop the decline of the west, but rather cause it by furthering decadence and atheism!
Every industry have interests in valuing byproducts.
In software industry, bugs are a byproduct and, there are ways to sell them as features.
There are compagnies to sell trashcans so trashes dont invade your house. You can produce gaz out of shit.
There are compagnies to sell enough memory, hand hard disk space so you have place to put leaks and fragmentations. You can even buy virus and spam cleaners.
Economically: Wastes have values and you can make money out of it by recycling. No matter if these are hardware or software wastes.
Léa Gris
Screw funding. It's irrelevant.
Screw specifications. Nobody has them anyways.
Give me a clear, predefined spec, and I'll meet it. I'll guarantee bug fixes,too.
But that's not how software evolves.
Despite careful attention, despite voluminous meetings, emails, and specifications, I never get a clear idea what the client needs me to develop until AFTER a prototype has been built.
In fact, I'd wage that there's a quasi-quantum principle at work: You can either work towards the customer's actual needs, or the predefined, agreed upon specification/costs/specifications. Answering either means ignoring the other.
Consider this the Heisenberg Uncertainty principle. The software is half-dead, half-alive. Either it meets the needs of the customer (and associated scope creep, bugs, ets) or the originally defined specification. Releasing the software defines whether the cat is dead or alive.
It seems that:
1) People will commit, in aggressive fashion, that they need something until they get it, at which point, they'll angrily point out all the flaws in it.
2) People don't actually know what they need until they see that what they have isn't it.
3) When you take anything produced because of (1), and then compare that to the feedback produced by (2), you end up with cases where the code is producing a result unexpected in the original design.
These are called bugs.
4) The only intelligent way to proceed with (1) and (2) is to consider software an iterative process, where (1) and (2) combine with (3) and lots of debugging to result in a usable product.
I have no problem with your religion until you decide it's reason to deprive others of the truth.
JML is a formal specification language for writing contracts for your Java programs. (It has nothing to do with UML or XML, other than sharing two letters.)
There are a number of quality research tools that understand JML including a compiler (jmlc), a documentation generator (jmldoc), a unit test generator (jmlunit), and an extended static checker (ESC/Java2), a kind of automated theorem prover, like FindBugs on steroids).
These tools and technology let you do design by contract and contract-based unit testing in Java 1.4 and are used by many universities and companies to help them build quality software. See the ESC/Java2 FAQ for more information.
Disclaimer: I am part of the research community that develops JML and the co-author and maintainer of ESC/Java2.
Joe
Joseph R. Kiniry
http://kind.ucd.ie/~kiniry/
Lecturer
UCD School of Computer Science and Informatics
Their secret is slave labor
People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf.
The reality about Correctness by Construction is that bugs do make it to the final product and the more complex the application the more bugs there is. In safety-critical applications, highly reliable software is simply not good enough, only because a single bug can be catastrophic. What is needed is 100% defect-free code, guaranteed. In other words, unless the program is guaranteed bug-free, it must not be deployed. Doubt = failure. The only way to achieve 100% reliability in software regardless of the complexity is to abandon the algorithmic model of software construction and to adopt a non-algorithmic, synchronous model.
Yikes! How did a divide by zero error do all that? Surely the application should have just crashed, leaving everything else running. Even if it did die entirely, why couldn't they simply reboot?
At the age of 17 I spent a week in the Praxis offices on "Work Experience" (Americans may think of this as a very short internship), to find out what developing software would be like as a career. This was a major formative event of my life: I thought that developing software sounded good, I really liked using Real Computers (multiuser, multiprocessing systems with powerful operating software, like VMS and SunOS), and the people impressed me greatly. It definitely set me on the path to the career in systems development and administration that I have today.
The person who made the biggest impression on me was the sysadmin. He got his own office-cube instead of having to share, he wore much more casual clothes and had a lot more hair and beard than most of the staff, he got to have big toys (several workstations, a LaserJet IIIsi big enough for an entire office that seemed to be his alone, etc) and he didn't seem to get much hassle from anyone else. This was obviously the job for me.
The sysadmin was obviously rather a BOFH. When I was sat at the UNIX workstation for the first time, and had poked around with basic file-handling commands, I asked "What's the text editor on this system?". He answered "emacs - e m a c s - here's a manual" and picked about 300 sheets of paper off the Laserjet and handed it to me.
I got to play with UNIX (SunOS), VMS, Oracle development environments. I still have the Emacs manual printout somewhere at home - it served me well when I went to University where printing anything out was charged by the sheet!
I'm very glad they're still around.
"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled"
"OS would at least have a thing or two to learn from the mere *reading* of the specifications from such projects"
In the same way that an air frame mechanic might gleam some knowledge from watching "The Great Biker Build Off" on the Discovery channel.
-Rick
"Most people in the U.S. wouldn't know they live in a tyrannical state if it walked up and grabbed their junk." - MyFirs
TFA cites a particular NSA biometric identification program which has "0.00" errors per KSLOC
And what would 0.34 errors look like?
or perhaps they had less than 5 errors in a thousand LOC.
From the IEEE article:
"The process is time-consuming. For the Mondex project, spec-writing took nearly a year, or about 25 percent of the entire development process. That was a long time to go without producing anything that looks like a payoff, concedes Andrew Calvert, Mondex's information technology liaison for the project. "Senior management would say: 'We are 20 percent into the project and we're getting nothing. Why aren't we seeing code? Why aren't we seeing implementation?' " he recalls. "I had to explain that we were investing much more than usual in the initial analysis, and that we wouldn't see anything until 50 percent of the way through." For comparison, in most projects, programmers start writing code before the quarter-way mark."
Isn't suposed that one has to give something working to the user and then correct any mistakes made?
IBM had a major intiative back in the mid-1980s called AD/Cycle which was tied to SAA (System Application Architecture) which was based on these and similar ideas prevalent back then. This is the old "holy grail" and an attempt to fix the waterfall methods of development, which had actually been since the early 1950s with mixed success in delivering software on-time and in-budget.
AD/Cycle involved not only IBM but a number of "AD/Cycle partner" companies like Bachman, and KnowledgeWare. KnowlegeWare's CEO was the former scrambling NFL quarterback Fran Tarkenton. A google of "fran tarkenton knowledgeware" will turn up references to Jim Martin, as well as some interesting things about how the company ended up.
An incredible amount of development money went down the rat-hole chasing the AD/Cycle dream.
The problem turns out to be the difficulty, if not impossibility, of creating rigorous specifications which produce useful results in the face of problems which aren't very well understood at the outset. The less the requirement is for a "black box" with well-defined inputs and outputs the more this is likely to be the case.
Many problems turn out to be wicked that there is a feedback loop between the implementation and the requirements. A classic book from the era was Wicked Problems, Righteous Solutions (http://www.amazon.com/gp/product/013590126X/102-5 477977-4320940?v=glance&n=283155)
Which might be considered one of the old testament texts pointing to today's "agile development" movement.
A non-software example of a wicked problem is city planning in which implementing changes in the road network, housing developments, shopping center location etc. all change the requirements for the same aspects.
Many wicked problems come from "requirements" which often do (or should or must) come from users. Often, the real requirements aren't known until an implementation is given to the users, who then might say, "yup, you implemented exactly what I asked for, but now that I see it, here's what I really want." Or, "Now that we've added this other thing (application, system, business division) why, doesn't this (work more like/interface with/replace/...) that."
Faced with this, a methodology based on "correct" construction from "rigourous" specifications simply moves the problem to debugging the requirements.
Until we do away with the need to change/adapt systems to changing/evolving requirements, which would likely involve eliminating users, this approach will have limited applicability, and will need to stand beside other more widely used incremental development models.
Why would you "upgrade?"
Bugs for Bucks, an industry standard.
The article comments:
These six principles are not in themselves difficult to apply, and may even appear obvious. However, in the authors' experience, many software development projects fail to deliver against many, if any, of these principles.
I'd argue that this is true, and the main reason that so many software products are so buggy is that most companies reward their developers for making buggy software, and punish them for making quality software.
The latter point is easy to show. I've worked on any number of products where I produced something fairly quickly that worked, and nobody could find any bugs. How was I rewarded? In nearly every case, I was laid off. I'd done the job that I was hired for, they didn't have another project that "matched my talents", and the software was so well documented that if any bugs did appear, others could fix them. So why should they continue to pay me to be nonproductive?
The lesson to developers is obvious: If you want to keep working here, you'll have to make sure that there is still work for you to do. This is not difficult. We all know the results.
It's especially easy to do when you look at the illogical demands that most companies put on programmers. I've been denied all sorts of information about the workings of the tools that I'm required to use, on the grounds that what I'm asking about is proprietary. So I have tools whose behavior isn't fully knowable, and I spend a lot of time looking at output and asking "What could that thing be doing to give such bizarre results?"
Of course, the funniest part of the article was the first principle, of "using a sound, formal notation for all deliverables". In most companies, this means a PowerPoint file.
My general conclusion is that lots of people say that they want quality software, but they intentionally prevent developers from producing it, and they punish developers who do so despite all the barriers. The result shouldn't be at all surprising.
Those who do study history are doomed to stand helplessly by while everyone else repeats it.
Of course, there are arguments that this does not constitute security. I think the concept of free fixes for bugs found by customers works a little better - it keeps all the stakeholders in the loop.
I think the "exclusion of warranty" terms that are common to most EULA's may be more at the heart. The typical consumer who has a problem will eventually run into this, and be forced to spend an insane amount on legal fees to get the EULA invalidated as unconscionable, or (more likely) give up in disgust.
Perhaps there would be an impact from a federal law stating that software makers whose license terms are found unconscionable in court must notify all registered users of the software of that ruling....
//Information does not want to be free; it wants to breed.
I'm not knocking the article or shops that follow those practices, since there are life critical applications where it is well justified (such as the ones discussed in the article). However, some here seem to be missing a few points when it comes to the desirability of these techniques for less critical software.
It's worth noting that the article starts out stating that the techniques involved allow production of up to 30 LOC/day. Thirty lines per day! Linux would have required over 493,000 man YEARS (at a reasonable guess +- 100,000 or so) to be where it is today at that rate. Assuming (very) generously that 2000 people could work on it full time without additional slowdowns for management overhead, that would have it ready to go somewhere around 2238 AD
It's simply not reasonable to compare engineering practices where life and limb is at stake to software practices where no such risk exists. It seems inevitable that software development is compared to the efforts to design a highrise or a bridge. What do you bet those cheap consumer devices that use a wall wart (so they don't have to be UL listed) have a higher defect rate?
That's not by any means meant to suggest that no attention should be paid to quality or that some shops don't pay nearly enough to it now. However, it is a very good reason we do NOT want everyone to be CMM5 or equivilant. If they were, we would literally grow old and die waiting for the software we want/need.
I suspect that to achieve less buggy software in a timeframe we can live in and for a cost we can afford will involve advances in modularity and reusability rather than high end development techniques. It will also require a legal and economic structure that don't require so much re-invention of the wheel.
mentioned in the article, you can download the reference manual from here
Check it out: http://www.nsa.gov/careers/students.cfm
I did an internship with State last summer and it was an amazing experience. I'm not sure I'll end up working for the government (given the rising price of living in the DC area and the lower salaries, it's looking less and less likely), but it was a very valuable professional experience in any case.
Check out the State student programs at careers.state.gov, and go for OVERSEAS internships - when you're based overseas as an intern, they give you many more responsibilities and depend a great deal on what you can do. It's a great way to get noticed and, whatever I end up doing, looks great on a resumé.
I know! let's sell a $200 PC to people that live in a country where the average annual income is about $13.50 on credit, then we have a large supply of workers. It may not quite be slavery, but it surely smacks of indentured servitude.
.net apps? write scam emails? blog?
We can probably get start up capital by calling ourselves a non-profit and asking for donations to help the third worlders that we are fixing to exploit.
The only question is, once we have all these new PC owners on the hook what are we gonna pay them to do, code
"Quality" as ambiguous. What I consider "quality" is different from what you consider "quality".
It's not just three, either; it is ALL of the non-functional requirements. At most two of them can be fully optimized in any engineererd system. In practice, the design of a system will be governed by the relative priorities of the non-functional requirements.
The set of non-functional requirements is very large, but you should recognize some of these:
Mental exercise: Choose any two from the above list, then explore how choosing any other item from the list would require a compromise to either of the first two chosen.
So, what "ability"s do you want to have today? ;)
@HbFyo0$k8 tH!$
For the production build, just change that one line to
As copyright owner of this comment, I authorize everyone to defeat any technological measure which limits access to it.
What a crock. A few people looked a Larry's Database and found huge
security holes and broken crap all over the place.
This so called "no bugs" code is open to inspection by outsiders, right?
Open to outsiders testing the NSA authentication? We can try the air controller
stuff out? Feh, this is such a silver bullet hype it should NEVER be an
article unless it is some analysis of a PR bullshit campaign.
I don't know how could you use Z to validate a specification with your final users unless they have a CS degree.
Use cases are semi-formal as Alistair Cockburn puts it. And that's a real advantage.
A combination of use cases, mock interfaces, prototyping and interpreting user requeriments (based on one's experience) are my best tools.
Decisions to cut corners on development and test costs exists in safety critical avionics systems on commerical aircraft. Both the FAA and EASA trusted Honeywell that the systems complied with Level A Hazard requirements of tolerating 1 failure in 10-9 operating hours, or 1 failure in 1 billion operating hours. This dangerous systems failure occured in the first 4 months of commerical revenue service! The blind trust in Honeywell resulted in a "rubber stamp" approval by FAA and EASA to allow operators of the aircraft to fly with the backup secondary navigation system disabled. Had this failure occured with the secondary navigation disabled, while flying in IFR, the results would have been catastrophic! Quote from the FAA AD Order: We are issuing this AD to prevent temporary or possible sustained loss of all modular avionics units (MAU), which triggers a cascade of failures in systems dependent on MAUs functionalities. Such failures could reduce the flightcrew's situational awareness and increase workload and consequently reduce the ability of the flightcrew to maintain the safe flight and landing of the airplane. prohibit dispatch of any flight with the integrated electronic standby system (IESS) inoperative, even though it is allowed by the current version of the Master Minimum Equipment List; and performing a test to determine proper operation of the network interface card (NIC) communications and repairing if necessary. This AD also requires installing a certain software version of the PRIMUS EPIC system http://www.airweb.faa.gov/Regulatory_and_Guidance_ Library/rgAD.nsf/0/a26cc12a9c5c33e686256f7a0054419 d?OpenDocument
I am a team leader in software development for Microsoft and would someone PLEASE tell me what a "bug" is?
And why you guys think they're such a BIG DEAL?!?
Sheesh!
Are they anything like the "features" we include in every piece of software we ship?
Well, since my code is mostly GPL, it does not have a binding warranty. But my policy (as with many other open source producers) is to fix bugs at no cost to the user; so in effect, open source software typically makes the same promise. There are probably many reasons why this is so, not least of which is simple pride in workmanship and desire to maintain a reputation.
you had me at #!
Likely 80% of the value of the Praxis method can be achieved without statistically provable languages.
Industry standard UML meets most of the requirements for sound formal notation.
Tooling for UML provides substantial validation of deliverables.
Iterative methods, RUP being my preference, meet the requirement for carrying out and validating the deliverables of small steps. (Note that CMMI still focusses on repeating the process, not validating the deliverables as the requirement.)
Any well structured method with low redundancy meets the requirement to say things only once. Most methods aren't well structured. RUP is pretty good, and can be made solid in this respect with a little attention.
From reasonably well done UML, test cases can be derived systematically that provide substantial coverage. Architects and designers can still create unthinkably complex solutions, but nothing in the article Praxis writes indicates that they have solved that problem in a technical way, but rather in a procedural way. Arguably, the Simplicity rule of XP comes closest to this Praxis practice, but I prefer the second half of the rule (don't add functionality before it is scheduled) to the first (do the simplest thing that could possibly work).
Any decent iterative method deals with the hard things first. RUP explicitly does in the Elaboration phase, for example, while XP has the less well articulated architectural spike and spike processes.
Having run XP and RUP projects and coached organizations around North America on the effective use of RUP, I can say that high developer productivity with low defects is eminently achievable, although not quite to the standard that Praxis achieves. A friend and CTO runs a variant of RUP for his shop and it's rare that defects are found by customers.
Cheers,
Mike Barnard
The reason it is used in the article though is that in the problem space where SPARK is most likely to be used, LOC/Day is still the most common method used to measure productivity (even for product that are developed with different approaches) It is full of problems, but I honestly have not seen a "better" approach that really worked. Function points were big for a while but counting them is more difficult (though honestly probably not more difficult then when the LOC/day crowd starts getting into the Equivilent LOC/Day math used when modifying an existing product). Several people on the thread have scoffed at LOC/day for productivity...I have not really seen anyone else present a viable alternative. The other thing to keep in mind is that there are other measures in place as well on most jobs like this such as defect density, rework, etc. All of these metrics have their problems to but in the end, when you are going to spend millions of dollars writing software, the pointy hair bosses (rightly so) do not want some guy just saying something like "Well, I think it will cost 1.5 million dollars because I submitted an ask slashdot question and that was the average response"....Whether or not such an approach would end up with a better estimate of productivity and final cost is left as an excercise for the reader.
--- Liberty in our Lifetime
I was given a project manager role at Nortel in 2000, and tried to implement some of this. It was virtually impossible; people did not want to (a) change their existing habits or (b) admit their were improvements to be made. While initially management and some on the team liked the ideas, implementing them was virtually impossible. Those who had to address the actual issues simply refused to do what was necessary. They said "yes" in meetings and went right back to the old work.
As a project manager over people in multiple departments and multiple locations, with hiring control over none, I was helpless without the support of executive mgmt, and they of course told me implementing the changes in question was my job. Which it was, but without power, a title is worthless.
Very, very vexing.
Of course, my inability to spell simple words ;-)
in the above post undermines it somewhat
Why is it that software engineers have to write so many dang essays? Maybe if we were as terse and un-expressive as the civil engineers our programs would work better. You ever see a few dozen essays on civil engineering in the bookstore?
I18N == Intergalacticization
Indeed, their technique seems to rely a lot on the sort of "Executable Comments" that act like assertions and other semantic statements. It could throw off their statistics.
I18N == Intergalacticization
Synchronous and deterministic languages such as SCADE permit to drastically reduce the number of bugs. As a former C/C++/java developer, I can tell you these tools are really ideal to develop safety critical sofware. And the code generator is DO-178B qualifiable up to level A, one of the most stringent certifications for embedded software in for civilian avionics, thus allowing you to certify the SCADE language and forget about low level testing on the generated C code. This tool is massively deployed at Airbus (A340 and A380). It is used for many other planes/helicopters