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What about safety critical software? For example software running inside airplanes, rockets, etc. Is that also easy, or it doesn’t count because it’s cross disc

by ojl 5y ago

What about safety critical software? For example software running inside airplanes, rockets, etc. Is that also easy, or it doesn’t count because it’s cross discipline? Although I would guess that many of those developers are indeed software engineers and not aerospace engineers by training.

deltaonefour 5y ago
>What about safety critical software? For example software running inside airplanes, rockets, etc. There's two ways of handling software that's safety critical. For software that needs an extreme level of safety... formal methods are employed to prove correctness and that software is bug free. For this part of computer science the foundational theory is well established. This part is really really hard which is why 99% of software engineers don't even know what I mean when I say the word "formal methods." It's so different from traditional software that it's never ever referred to when people use the term "software engineering." We have a rudimentary form of it in the form of type checking in our programming languages. But there's another part of it as well involving empirical testing. This is popular in the industry and engineers use the term unit testing or regression testing to refer to it. It's a shot in the dark. Basically taking a couple test samples out of an huge sample space of possible tests and saying if those samples work then likely the whole thing works. IF you want to prove your program correct using this method you would have to run every single possible test that exists on your program. It's untenable so we informally rely on a statistical phenomenon of taking a sample of tests out of a huge sample space. This is the most common way of creating safety critical software that everyone uses because it's easy. Don't mix tediousness with easy. Using this methodology is very tedious, but I would argue quite easy. Also redundancy and fail-safes in logic are used throughout the system for safety critical software. This again is easy to implement but tedious. >Although I would guess that many of those developers are indeed software engineers and not aerospace engineers by training. Yeah most of the mathematics in this case is modeled by system engineers or other engineers that are more specialized than the math is handed down to the software guys who only need to understand the equations but they don't need to understand how to derive those equations. During testing the software engineers and hardware engineers would have to work together to make sure the software operates the hardware correctly. If the hardware is simple or well established and accessible often the software engineer can do the testing alone. Sometimes the engineer of the physical system itself just programs it himself. Alot of non-software engineers are like this because software engineering tends to be easy so they can just learn how to program.
- ojl 5y ago
  I agree that formal methods probably isn’t as well known as it could/should be. > Also redundancy and fail-safes in logic are used throughout the system for safety critical software. This again is easy to implement but tedious. I wouldn’t call implementing redundancy and fail safety for a fairly complex system easy though. Tedious, yes. And tedious but easy probably could describe lots of other engineering work as well, not only software. > Sometimes the engineer of the physical system itself just programs it himself. Alot of non-software engineers are like this because software engineering tends to be easy so they can just learn how to program. They might believe that it’s easy to write some software that in some way solves the problem but in my experience they don’t always engineer good software, and don’t always realise that their small part of the program has to work together with a huge amount of other software. Not that all software engineers do this either..
  - deltaonefour 5y ago
    >I wouldn’t call implementing redundancy and fail safety for a fairly complex system easy though. What's the cutoff for IQ then to implement a redundancy. Is there really a mediocre software engineer who can't do it. My argument is with a lot of effort any software engineer can do it. And if anyone can do it.. it's easy. >They might believe that it’s easy to write some software that in some way solves the problem but in my experience they don’t always engineer good software, and don’t always realise that their small part of the program has to work together with a huge amount of other software. Not that all software engineers do this either.. As I've stated before. There's no logical theory behind program organization. How you integrate software together is mostly gut level arbitrary decisions and many times those decisions come out wrong and people make workarounds to fix things. It all usually ends up working in the end. It may be ugly but it works and then everyone rewrites and the cycle begins anew. Nobody in this area of software truly knows what they are doing. Hence why it's easy. Let me be clear about what I mean by easy. Easy means anyone can do it. If a lot of hardwork and problem solving effort is involved... it doesn't matter and it's still easy because anyone can do it.

by ojl 5y ago

deltaonefour 5y ago

>What about safety critical software? For example software running inside airplanes, rockets, etc. There's two ways of handling software that's safety critical. For software that needs an extreme level of safety... formal methods are employed to prove correctness and that software is bug free. For this part of computer science the foundational theory is well established. This part is really really hard which is why 99% of software engineers don't even know what I mean when I say the word "formal methods." It's so different from traditional software that it's never ever referred to when people use the term "software engineering." We have a rudimentary form of it in the form of type checking in our programming languages. But there's another part of it as well involving empirical testing. This is popular in the industry and engineers use the term unit testing or regression testing to refer to it. It's a shot in the dark. Basically taking a couple test samples out of an huge sample space of possible tests and saying if those samples work then likely the whole thing works. IF you want to prove your program correct using this method you would have to run every single possible test that exists on your program. It's untenable so we informally rely on a statistical phenomenon of taking a sample of tests out of a huge sample space. This is the most common way of creating safety critical software that everyone uses because it's easy. Don't mix tediousness with easy. Using this methodology is very tedious, but I would argue quite easy. Also redundancy and fail-safes in logic are used throughout the system for safety critical software. This again is easy to implement but tedious. >Although I would guess that many of those developers are indeed software engineers and not aerospace engineers by training. Yeah most of the mathematics in this case is modeled by system engineers or other engineers that are more specialized than the math is handed down to the software guys who only need to understand the equations but they don't need to understand how to derive those equations. During testing the software engineers and hardware engineers would have to work together to make sure the software operates the hardware correctly. If the hardware is simple or well established and accessible often the software engineer can do the testing alone. Sometimes the engineer of the physical system itself just programs it himself. Alot of non-software engineers are like this because software engineering tends to be easy so they can just learn how to program.

ojl 5y ago
I agree that formal methods probably isn’t as well known as it could/should be. > Also redundancy and fail-safes in logic are used throughout the system for safety critical software. This again is easy to implement but tedious. I wouldn’t call implementing redundancy and fail safety for a fairly complex system easy though. Tedious, yes. And tedious but easy probably could describe lots of other engineering work as well, not only software. > Sometimes the engineer of the physical system itself just programs it himself. Alot of non-software engineers are like this because software engineering tends to be easy so they can just learn how to program. They might believe that it’s easy to write some software that in some way solves the problem but in my experience they don’t always engineer good software, and don’t always realise that their small part of the program has to work together with a huge amount of other software. Not that all software engineers do this either..
- deltaonefour 5y ago
  >I wouldn’t call implementing redundancy and fail safety for a fairly complex system easy though. What's the cutoff for IQ then to implement a redundancy. Is there really a mediocre software engineer who can't do it. My argument is with a lot of effort any software engineer can do it. And if anyone can do it.. it's easy. >They might believe that it’s easy to write some software that in some way solves the problem but in my experience they don’t always engineer good software, and don’t always realise that their small part of the program has to work together with a huge amount of other software. Not that all software engineers do this either.. As I've stated before. There's no logical theory behind program organization. How you integrate software together is mostly gut level arbitrary decisions and many times those decisions come out wrong and people make workarounds to fix things. It all usually ends up working in the end. It may be ugly but it works and then everyone rewrites and the cycle begins anew. Nobody in this area of software truly knows what they are doing. Hence why it's easy. Let me be clear about what I mean by easy. Easy means anyone can do it. If a lot of hardwork and problem solving effort is involved... it doesn't matter and it's still easy because anyone can do it.