When Bugs Aren't Allowed 489
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."
nearly unlimited funding (Score:5, Funny)
Re:nearly unlimited funding (Score:5, Interesting)
Re:nearly unlimited funding (Score:3, Insightful)
The key point is this: small teams. It's a lot easier to find the people who can produce 10x better (in terms of rate of writing, clean/bug free code, whichever metrics you care for) when you need to find 3 or 5 or 10 people. You can't staff a whole large application development project with the best gurus: there aren't enough out there in the world.
Re:nearly unlimited funding (Score:5, Informative)
Jedidiah.
Re:nearly unlimited funding (Score:5, Interesting)
And why aren't there? Geeks lament the fall of IT and Computer Science programs at institutes of higher learning, and wonder why people don't want to go into these fields. If there was demand for programmers of the caliber you mention and companies willing to pay salaries deserving of such abilities there would be more people studying towards such a position.
But if companies are going to just throw up their hands and say "we can't hire competent people, there aren't enough of them in the world, they only doom themselves to a continued shortfall in talent, and an increase in buggy software.
Nursing is a profession that is always looking for new people and folks who didn't make it through the four-year grind back when they were young are flocking to it because the jobs are waiting. If companies held their coders to a higher standard, they would trim some of the fat in their projects and have jobs open for people willing to do the work. The result would be more productive teams and better applications, a win-win situation.
Re:nearly unlimited funding (Score:3, Insightful)
But if companies are going to just throw up their hands and say "we can't hire competent people, there aren't enough of them in the world, they only doom themselves to a continued shortfall in talent, and an increase in buggy software.
What they really meant was "we can't hire competent people at the same prices as Jimmy the mounth-breather." Take that as you will.
Re:nearly unlimited funding (Score:3, Insightful)
Or on the other hand, "We could hire three college graduates, who will then do three times as much useful work in three times the amount of time required by the old guy with total experience greater than the thre
Re:nearly unlimited funding (Score:4, Interesting)
The projects I am involved with today won't wait five years for programmers. This is business fact; if they aren't started now, and completed in an economical timeframe, then companies will go out of business and not be around to hire those better programmers in 5 years.
If you shift the question around to "should we set project and programmer standards" and "should standards improve and evolve over time", and the statement to "current standards are inadequate and irresponsible" then sure, no disagreement.
In many cases, development problems are the result of not even following what industry standards and best practices are in place now.
And one thing I don't want to see is formal programming CS programs which produce CS professors exclusively
Nontrivial problems to solve. If it was easy, everyone would be doing this stuff right already. That obviously isn't true yet...
Re:nearly unlimited funding (Score:3, Insightful)
Maybe we could start by not assuming that CS grads shoul
Re:nearly unlimited funding (Score:3, Interesting)
I don't want to say that you can't be a Computer Scientist without being a good Software Engineer, but I will say that you can't be a Good Computer Scientist without being a good Software Engineer. Every one of the skills a good software engineer needs together forms a subset of the skills required by a good computer scientist. Thou
Re:nearly unlimited funding (Score:3, Interesting)
In large organizations, there are already a lot of mediocre people and policies built to deal with that reality. People who know what they're doing face an uphill battle in getting anything done. There are large beaurocracies in place to tell people what standards th
Re:nearly unlimited funding (Score:5, Insightful)
People differ in ability in every field; the bell curve is real, and only the people who are at the high end of the curve can be considered one of "the best gurus". They will never constitute a large percentage of the group. Ever. Furthermore, there is usually a huge difference in performance between people who are in the top 10% of their field and those who are in the top 0.1% of their field. Most people would consider those in the top 10% as "the best gurus", but really it's only that tiny segment at the very top who deserve the appelation. Even then, you can expect a marked difference between those in the to 0.1% and those in the top 0.01%. Fact of life, folks.
Re:nearly unlimited funding (Score:3, Insightful)
But if companies are going to just throw up their hands and say "we can't hire competent people, there aren't enough of them in the world, they only doom themselves to a continued shortfall in talent, and an increase in buggy software.
Part of the problem is simply that the higher you draw the threshold, you start to get i
Re:nearly unlimited funding (Score:4, Insightful)
What's the quickest way to paint the roof of the Sistine chapel? Are you going to be able to hire 30 artists with enough talent, or should you stick with the one that is qualified and a couple assistants and just wait a few years?
Can you train 30 artists to be good enough to do the work? How about 300?
After a point, being a super-coder is just as much of an art. You won't be able to produce these people, it's kinda in their soul. Great musicians pick up their first instrument and know it's what they are going to do--what they are made for. My guess would be that if you have had access to a computer for over a year and you aren't coding yet, you'll probably never be a really great coder--a real computer artist couldn't have resisted.
Hmm, maybe a better word that Guru or Architect would be Computer Artist or Code Artist? It should convey the relative rarity much better.
This should be obvious. Every other art has it's gurus, and they are usually the top 1%, 99% of the others in the field simply will never be able to do what the gurus do, regardless of training or experience. I'll never play the piano like a savant that started at age 3, period.
Rules of thumb (Score:4, Insightful)
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.
the old axiom applies (Score:3, Insightful)
The old technology axiom applies:
High Speed, Low Cost, High Quality.
Pick 2 out of 3.
Re:the old axiom applies (Score:3, Insightful)
Re:nearly unlimited funding (Score:5, Insightful)
Jedidiah.
So... (Score:3, Insightful)
Re:nearly unlimited funding (Score:2)
At any rate - there's no such thing as bug free software. Never will be. There is such a thing as a product that appears to work without bugs and I think thats
Re:nearly unlimited funding (Score:5, Funny)
10 PRINK "HELLO WORLD"
Damn.
Re:nearly unlimited funding (Score:3, Insightful)
As you can see, even the simple 10 PRINT "HELLO WORLD" isn't bug free. To make bug free software you don't need to catch most errors, you need to catch every possible error.
Nearly unlimited risk helps too (Score:5, Interesting)
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.
Nearly unlimited risk helps too-Theorem. (Score:4, Informative)
http://www.edn.com/archives/1995/080395/16df4.htm [edn.com]
"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
Wow (Score:3, Funny)
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?
Re:nearly unlimited funding (Score:2)
Re:productivity around 30 LOC per day (Score:4, Insightful)
These guys seem to be claiming they can reduce redundancy in the design work, and rework in the verification work. They're doing it by using a design-description method that prevents unambiguity (and therefore using a team that is TRAINED to write unambiguous requirements, so their magic language may not be the key), a coding method that avoids unprovable structure (and probably eliminates a lot of other sorts of flexibility), and a verification method that first validates the design and then verifies the code as it's produced (no new value there as everything has to be touched at least once anyway, and if a big bug turns up that causes a lot of code to be redone you have to redo formal verification on those units again; something that's less likely if formal verification is delayed until full-alpha code is demonstrated, having been informally verified along the way).
Their claims of massive error reduction are, at best, anecdotal. Let's see them do this after taking over a half-coded project with minimal design requirements, a hard deadline, and a budget that can be cut by governmental forces at will.
Re:productivity around 30 LOC per day (Score:3, Interesting)
Which is precisely the kind of project they avoid, because it's a disaster waiting to happen. Praxis caters to customers who want quality, and are willing to do what it takes to get it.
Re:productivity around 30 LOC per day (Score:5, Insightful)
In as much as a civil engineer depends on control factors via refusing customers who demand that the building have 6 stories not 4 just one month before construction is due to finish, yes. Real world engineering makes certain demands of the client. Someone who wants to build a treehouse for their kids doesn't consult an architect and a civil engineer, and civil engineers don't take contracts from people who refuse to set out some limits on what they want built, and what they expect of it.
Praxis uses solid engineering. Their "Correct by Construction" approach is solidly grounded in axiomatic mathematics and uses similar sorts of formal calculations and logical and mathematical proofs as you might expect to see from civil, electrical, aerospace, or ny other kind of engineers. Take the time to read sample chapters [praxis-his.com] from the SPARK book to get an idea of exactly what they are doing. There is very definitely quite solid engineering going on.
Re:productivity around 30 LOC per day (Score:5, Informative)
Their claims of error reduction are based on the development method and a lot of the important stuff happens very early on, taking over a half finished project that failed to follow such a method is of course not going to work. They can't make existing code bug free, but they can write new code that has vastly less errors than most software. As to hard deadlines and budgets - as far as I am aware Praxis already works with deadlines, and apparently [slashdot.org] their project for Mastercard was done on a fixed flat fee, so working with fixed or limited budgets doesn't appear to be an issue either.
Jedidiah.
Re:productivity around 30 LOC per day (Score:3, Funny)
I would have said no payments for the first six months, then 19.7% after that.
Speaking of bugs... (Score:2, Funny)
No Bugs for NSA? (Score:5, Funny)
*rimshot*
Re:No Bugs for NSA? (Score:2)
Re:No Bugs for NSA? (Score:5, Interesting)
http://www.rockwellcollins.com/news/page6237.html [rockwellcollins.com]
Rockwell collins designed a secure processor for the NSA that PROVABLY can run multiple threads where each thread can get no information about the others. That way they can run processes with different clearance levels on the same CPU.
Model checking can make you big bucks if you can find the customers to pay for it.
Whatever (Score:5, Insightful)
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.
Here, here... (Score:5, Interesting)
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.
Re:Here, here... (Score:5, Funny)
Re:Here, here... (Score:2)
Re:Here, here... (Score:5, Insightful)
Many years ago, I remember reading a quote from an employee at a major aircraft subcontractor along the lines of "If my company paid as much attention to the quality of our work as Microsoft, airplanes would be falling out of the sky on a weekly basis, and people would accept this as normal." I've heard many people, even programmers, claim that bugfree programs are impossible to write. They are not- they just cost far more in time and money than most companies can afford in this commercial climate. When success depends largely on being first to market and bugs and crashes are accepted as a normal fact of life, then they always will be a normal fact of life.
Unfortunately, I think the blame lies at least in large part with the consumer. As long as people put up with programming errors in a $500 software suite that they would never accept in an $80 DVD player, we will continue to have these problems. Unfortunately, too many people still consider computers to be too much black magic that is out side of their (or anyone else's) grasp. Most people have little to know knowledge of how their car works under the hood, but they still believe that the engineer who designed it has enough knowledge to do it without making mistakes and expect the manufacturer to pay for those mistakes when they happen. Why should they believe any differently about the people who write the software they use?
Re:Here, here... (Score:3, Informative)
It sounds apocryphal, but I really want it to be true. :-)
It really is true, but it happened in a simulator [66.102.7.104].
Re:Here, here... (Score:3)
Bull. I have a Mac and know a slew of basically unskilled users who also own them, and they work fine without any maintenance at all. Unless you count clicking "Install" on the auto-update utility "a lot of work."
You change your car's oil because it's a consumable; there's nothing to compare in a computer (well, maybe the bearings in the fans, but those are probably good for several million rotations). A well-design
Re:Whatever (Score:4, Informative)
I was pitching for "how people would like to think things are" rather than how things actually work. In practice Praxis, at least, does deliver such software, and does so with extremely low defect rates. They are proof that it can be done, even if it isn't always how things work now.
Jedidiah.
Re:Whatever (Score:2)
So a few bugs in commercial avionics is acceptable?
Bugs and Beta testing. (Score:5, Insightful)
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.
Re:Bugs and Beta testing. (Score:3, Informative)
Re:Bugs and Beta testing. (Score:3, Informative)
However, fingerprints are not an entirely genetic characteristic. Scientists love to use this topic as an example of the old "nature vs. nurture" debate. Fingerprinting, along with other physical characteristics, is an example of a phenotype -- meaning that it is determined by the interaction of an indivdual's genes and the developmental environment in the uterus.
The ultimate shape of fingerprints are believed to be influenced by environmental factors d
IEFBR14 is the perfect example of your point (Score:5, Interesting)
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.
Re:Bugs and Beta testing. (Score:3, Funny)
I second the motion! (Score:5, Interesting)
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.
Still can have bugs (Score:4, Interesting)
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.
Re:Still can have bugs (Score:2)
sPh
Re:Still can have bugs (Score:5, Interesting)
No one can ever make something that is completely "bug-free" - even in traditional, non-software disciplines. All you can do is make the probability that the system will work as high as possible. Praxis has some techniques that can help developers create software with a much higher probability of working correctly than it would otherwise have. That's a good thing, even if it doesn't result in perfection.
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.
It's the fact that Praxis relies on static checking far beyond anything you've ever seen (using a carefully designed subset of Ada that can be statically checked in all sorts of interesting ways) that helps to ameliorate this problem, since the static check is effectively equivalent to an exhaustive input/output test.
Re:Still can have bugs (Score:5, Informative)
Praxis uses a subset of Ada together with annotations in a language called SPARK to write most of their software. They also have tools which work with such code to do considerable static checking - much as type checking catches errors, checking the annotations catches many more just as efficiently - and generate proof obligations, which they can then formally prove. That means, for many of their projects, the actaully have formal proofs that buffer overflows cannot and will not occur.
However in practice this challenge is a little unpractical when deadlines and interopability with closed source software get in the way.
Again, this is where the tools and methodology matter. Praxis delivers code as fast as traditional development techniques, so deadlines aren't the problem. They can do this by using SPARKAda and the SPARK tools to do exceptionally robust testing on a regular basis for each incremental deliverable. This allows catching bugs much earlier, when they are cheaper and faster to fix.
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.
It is pretty much this sort of mathematical rigor, injected into the development process as early as possible, that allows Praxis to produce the sort of defect rates that they do. And yes, that does mean that developers at Praxis are probably required to have stronger math and CS backgrounds that elsewhere. Given that, due to their ability to deliver almost bug free software in very reasonable time frames, Praxis charges 50% more than the industry daily rate, yes having a math or CS degree really does count for something - more money for starters.
Jedidiah.
Re:Still can have bugs (Score:2)
Non turing complete programming languages (Score:2)
Re:Non turing complete programming languages (Score:2)
After that you need control structures. If you were to not allow control structures, I think it would be very hard to make an OS. (Unless it's one of them "Hello World" OSes, that then crash and reboot.)
I'd say it's impossible to write an OS in a non-turing complete language.
Uh (Score:4, Funny)
Re:Non turing complete programming languages (Score:3, Interesting)
That's not so relevant in real-time systems, though, which is where SPARK really shines. It's quite an achievement b
economics (Score:5, Insightful)
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.
Re:economics (Score:2)
Most other Industries start in this state (You can have any colour as long as its black), but once something becomes enough of a commodity, inevetably the voice of the customer starts to win out.
Either they sue you into the stoneage for destroying their billion dollar enterprise with your crap thats not fit for purpose or they begin to understand that defects COST them and purchase fr
Re:economics (Score:3, Insightful)
No, that's not it either. Bugs happen because the people who buy the software do not demand bug free code. I do write software for a living. When the customer demends bug-free software he gets it.
I've been around the building bussines too. when I see por work there, say badly set tile, I don't blame the tile setter so much as the full ideot who paid the til
Bugs are fine... (Score:5, Insightful)
Re:Bugs are fine... (Score:2)
I tried that, doesn't work.
When bugs aren't allowed? (Score:5, Funny)
Not unlimited funding (Score:5, Interesting)
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...)
Re:Not unlimited funding (Score:3, Interesting)
Don't forget tools - I have to do the majority of my work in C++ with Visual Studio, and there has been more than one occasion where I had to look at the generated assembly code to figure out what was going on when VC++ screwed something up ("WTF - where'd that JMP come from?!?"), and then spend a little more time coming up with an alternate way to express the same logic that the compiler wouldn't fuck up. You can mathematically prove the correct
Re: Not unlimited funding (Score:3, Insightful)
Do I get to strap them down, put bamboo splinters under their fingernails, and inject them with truth serum?
There isn't much that you can do when the customer is uncooperative and doesn't want to get involved or admit their ignorance.
Automatic Verification Systems? (Score:2)
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?
Re:Automatic Verification Systems? (Score:2)
You might be able to s
2 defacto models of software development (Score:5, Informative)
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.
There's another factor though (Score:3, Insightful)
Much harder if you are making something that has to r
Secure code (Score:3, Interesting)
Re:Secure code (Score:2)
The key to this point, obviously, is to know exactly what you want when you start and have a detailed outline of the components that will enable it.
seems kinda small (Score:3, Interesting)
X windows in Ada for ATC (Score:5, Funny)
The right programming language helps hugely (Score:5, Interesting)
A good example of people writing complex but bug-free software under time pressure is the annual ICFP Programming Contest [icfpcontest.org]. 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 [gwydiondylan.org]
- Haskell [haskell.org]
- OCaml [inria.fr]
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.
Re:The right programming language helps hugely (Score:5, Informative)
If you find that interesting, but Ada isn't to your taste, you can try JML [iastate.edu] for Java which provides similar (but lacking quite the same robustness and tool support) annotations. JML lets you automatically generate JUnit tests based on your annotations, and with ESC/Java2 allows for extended static checking.
If, as you appear, you are more of a fan of functional languages then I'd suggest you check out Extended ML [ed.ac.uk] and HasCASL [uni-bremen.de] which provide similar sorts of formal specification capabilities for ML and Haskell. Tool support for these is still a little limited, but they are both quite powerful and provide very expressive specification syntax.
Jedidiah.
Re:The right programming language helps hugely (Score:4, Informative)
Yesterday, I had to do an analysis for someone on whether eliminating the electoral college would hurt states with a low turnout or not. The data is online in a nice plain text table, and the calculations are dirt-simple and take under a second in whatever language you want. Gawk all the way, got the project done in half an hour, if I had used C or Java I'd probably have spent triple the time for the same results. Several months ago I had to do image processing with a GUI wrapped around it -- C for the number crunching, .NET something or other for the GUI. A year ago I had to write a distributed application to do some crazy intense number crunching -- wrote the number crunching loop in C*, wrote the network code and interface in Java.
* Credit where credit is due: I borrowed 99.95% of it from GPLed code designed to do the same task on a single machine.
Re:The right programming language helps hugely (Score:5, Interesting)
My cards on the table are that I've entered each of the last six years with 3 - 5 person teams using Dylan, collecting 2nd place twice and Judge's Prize twice.
but one of the reasons the International Conference on Functional Programming Contest is consistently won by Functional Programmers is that it appeals heavily towards them both in terms of getting the word out to people and in terms of task selection.
Getting the word out doesn't seem to be the problem. Last year for example there were 161 first-round entries. Only 38 entries -- 24% of the total -- were in one of the languages I mentioned as being consistently sucessful: 1 in Dylan, 16 in Haskell and 21 in OCaml.
I also disagree about task selection. C and C++ and Java are every bit as suited to the sort of tasks in the ICFP contest as they are to the things they are normally used for. What they are not suited to is doing them in a short period of time, in an exploratory programming manner, and without bugs.
Type safety, fast compiled code, garbage collection -- all of these were all but irrelevant to the last two years' tasks. The main stumbling block both years had been writing parsers.
Parsers aren't the problem. C has had parser generators for thirty years and besides the messages to be parsed were totally trivial. Dylan doesn't yet have any good tools for writing parsers, but it doesn't matter because we were able in the first eight hours of the contest to hand write a complete and correctly functioning (but stupid) program using nothing more complex than regular expressions, leaving the remaining 64 hours to think of something clever to do. Anyone using Perl or Python or Ruby probably finished the infrastructure even quicker than we did.
Re:The right programming language helps hugely (Score:3, Funny)
> had used C or Java I'd probably have spent triple the time for
> the same results.
Heh, that was probably a 1-liner in APL.
Of course APL programs longer than 1 line are usually unmaintainable, but no language is perfect...
Re:The right programming language helps hugely (Score:4, Interesting)
More to the point, they're all basically functional, and Haskell is a pure functional language.
I think we're going to see functional languages get a lot more popular soon because they're better for concurrent programming, and we're about to see a lot more multi-processor PCs.
My Bogosity meter is wiggling (Score:4, Informative)
An interseting point that few managers understand (Score:5, Interesting)
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 to wonder.... (Score:5, Insightful)
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
Re:I have to wonder.... (Score:4, Informative)
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:
I think, to be honest, that it is a combination of a number of the factors you mention.
Why aren't schools teaching this methodoly thoroughly? Why aren't this toolset and programming language taught in school by default?
To do proper formal specification, one of the key parts of Praxis' Correct by Construction approach, does require a decent solid mathematical background. I think a lot of CS departments, facing students who want vocational training, struggle to demand the sort of mathematical requirements that are needed. As to SPARK - it is something that Praxis developed themselves, and it is proprietary (the toolset at least, the annotation language is well documented). You can pick up a book and learn the language, but the tools cost money if you want to use them commercially. On the other hand, the base specification language Praxis uses, Z [wikipedia.org], is entirely open, and there are a variety of freely available tools for it [sourceforge.net]. There are also other specification langauges (I quite like CASL [wikipedia.org] which has a number of useful extensions) that have freely available tools associated with them. There's also JML [iastate.edu] and ESC/Java2 [secure.ucd.ie] which are freely available and seek to provide the same sort of functionality or Java that SPARK adds to Ada. There are places that teach JML [uni-bremen.de], but they are still few and far between.
Programmers are asked to do the impossible.
I think this is a big part of it in some ways. Partly this is because, for a large number of software projects, the degree of exactness and quality just isn't required. I don't need a professional architect to help me build a doghouse in my backyard (though I'd certainly want one if I was building a skyscraper), and I don't need assurances of bug free software for a simple web front-end to a database. At the same time programmers are often unwilling to let customers know exactly what the limits are when developing software. To quote you: "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?"; if software engineers aren't prepared to stand up for quality and tell customers that somethings can't be done without sacrificing the quality of the product the problem will remain. In part I think this is due to the fact that software development is a young industry, and programmers are still of the mentality that they need to do everything they possibly can to please a customer. Partly it's because software projects are diverse (as are building projects!) and sometimes it's okay to make late changes; sometimes it's how things ought to be done - the key is to identify exactly what sort of project it is as early as you can. Are you building a treehouse for your kids, which doesn't require exactness and benefits from incremental design and feedback, or are you building a 4 story building where quality is important, and late changes will jepordise that?
Programmers are a bunch of bozos who know shit about proper engineering.
Sadly this is partly the case. There are an awful lot of cowboys out there when it comes to software engineering. There are, of course, a lot of fantastic programmers as well who are otherwise beset by some of the other points mentioned. There is, however, a remarkable degree of tolerance for cowboys, sloppiness and lack of quality in software engineering that you don't see in other engineering disciplines. Partly I thin
Related reference page about tests (Score:3, Insightful)
Automatic generation of code? (Score:4, Interesting)
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.
But what does the customer need? (Score:4, Insightful)
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.
Praxis made me the geek I am (Score:3, Interesting)
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.
You mean, it's not hard when... (Score:3, Insightful)
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.
Re:Paper doesn't mention open source model (Score:5, Insightful)
Linux, Firefox, and OpenOffice are some of the best software on the planet. I think is a good practical testament to the OSS philosophy.
And yet they all still suffer from a metric crapload of bugs. Praxis produces software with so few bugs that they are willing to provide a warranty that says they'll fix any bug found within the first 10 years, for free. If their software had the defect rate of Firefox or OpenOffice they'd be bankrupt in short order.
Re:Paper doesn't mention open source model (Score:3, Insightful)
Re:Do you think it would help? (Score:3, Interesting)
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 d
Re:Microsoft error rates (Score:3, Informative)
You say that like it's a good thing!
The only way Windows will be fixed is to start with a clean sheet of paper, completely re-write the entire code base. There are errors in XP that were unfixed errors in 98. I've seen 2 errors in XP that were identical to ones in 3.1. That is a lack of attention to detail.
Re:Microsoft error rates (Score:5, Funny)
If operating systems ran airlines:
UNIX Airways: Everyone brings one piece of the plane along when they
come to the airport. They all go out on the runway and put the plane
together piece by piece, arguing non-stop about what kind of plane they
are suposed to be building.
Mac Airlines: All the airline personnel look and act exactly the same.
Every time you ask questions about details you are gently but firmly told
that you don't need to know, don't want to know, and everything will be
done for you without your ever having to know, so just shut up.
Windows Air: The terminal is pretty and colorful, with friendly stewards,
easy baggage check and boarding and a smooth take off. After about 10
minutes in the air the plane explodes with no warning whatsoever.
Windows NT Air: Just like Windows Air, but costs more, and uses much
bigger planes, and takes out all other planes in a 40 mile radius when it
explodes.
Linux Air: Disgruntled employees of all other OS Airlines, (with UNIX
geeks who finally figured out what kind of plane they were suposed to be
building) decide to start their own airline. They build the planes,
ticket counters, and pave the runways themselves. They charge a small fee
to cover the cost of printing the ticket, but you can also download the
ticket and print it yourself. When you board the plane you are given a
seat, four bolts, a wrench, and a copy of the Seat-HOWTO.html. Once
settled, the fully adjusable seat is very comfotable, the plane leaves
and arrives on time without problems, and the in-flight meal is
wonderful. You try to tell the customers of the other airlines about the
great trip, but all they can say is, "You had to what with the seat?"
with apologies to Doc Searls and Linux Journal.
Re:Microsoft error rates (Score:3, Funny)
Re:Flamebait this! (Score:3, Insightful)
When you are talking about an air traffic control system, you can set a very specific set of requirements. The Air Traffic Contr
Re:Well Duh! (Score:3, Insightful)
That's pretty much what I was thinking - that this company's results are not especially due to their methods, but due to hiring highly-skilled developers who know what they're doing and care about doing it right.
Half of the "enterprise" applications I've worked with were built on a foundation of absolute shit - too many elements of their core design were based on flawed thinking. No amount of
Re:Requirements... don't we all wish (Score:3, Interesting)