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Sure. So UML is based on two main research areas - UML class diagram is based on rational algebra theory. A correct UML class diagram should follow the same nor

Sure. So UML is based on two main research areas - UML class diagram is based on rational algebra theory. A correct UML class diagram should follow the same normalization roles as defined by Codd seminal paper - "A Relational Model of Data for Large Shared Data Banks". You can ask, how does Prof Codd knows that this is is the correct way to describe and implement data. Well this follow directly from set theory. Again, how do we know that set theory works - well here we are the level of axioms of the set algebra. BTW, this Codd work was also "hacked" again by system R research which invented SQL. The other part of UML is based on finite state machine, which originated by Turning, and later refined by the work of David Harel on state charts. Again, those are theoretical CS tools. However, the work of Harel on state charts, was originated from the work on the Israel first aircarft (to be cancelled later), where he needed to define the the missile system. If you are interested on how those tool originated and later combined see the work of David Hay - "UML-Data-Modeling-Reconciliation" Those tools are useful in scale. For example, system with 3000 different use cases. Or for example you have 200 - 500 classes, each is a state machine. Again, since there is no software professional standard (not software engineering bar exam), you can or cannot use anything.

deleted 7y ago
[deleted]
geofft 7y ago
That's, again, not what I'm asking. I'm not asking for the theoretical underpinnings of why this is a good way to represent 200-500 classes. I'm asking why, if I and two coworkers need to code up 200-500 classes by next month to meet a promise to a customer, spending time on UML will make the customer happier. I have a programming language that itself has strong theoretical underpinnings. I also have a pretty good hunch that in about two weeks there will be a last-minute requirement that changes the structure of the data model, and in about three weeks there will be a production outage of another system that distracts my attention. Will UML help me deliver software with changing requirements faster and more accurately? How does it compare to other options in my toolbox, like using a less verbose language that doesn't have real OO (which in my experience is often the right choice) and because of its conciseness is easier to make major changes to? How do I tie the UML object structure to my programming language, and why is it better than using a strongly- and richly-typed language in the first place? Why do I see many successful software projects that as far as I can tell don't use UML?
- streetcat1 7y ago
  First, I must say that the inventors of UML saw it as the last layer. The grand vision was a complete code generation from UML diagrams. And this was the overall grand vision that drove OO in general. I think that this is was happening now with the "low code" startups. The whole idea is to separate the global decisions (which are hard to change) - e.g. architecture, what classes, what each class do, from the local one (e.g. which data structure to use). So you would use UML for the global decisions, and than make programming the classes almost mechanical. Of course the customer do not see that. The customer see the user interface, and if the overall use cases are implemented correctly. Hence using those tool might help or not. Lets take architecture for example, why do people use an architect ?. Why does architect needs diagrams? Will the owner care of the architect use diagrams?
  - geofft 7y ago
    Again, I am not asking how to use UML, or why the inventors of UML designed it in a certain way, or why it sounds like it could be a good idea, or whether there are other systems like UML that are good ideas (I can just use those systems directly then!). I am asking what evidence there is that UML helps me deliver better products more efficiently. Are there successful software projects that do this complete code generation thing (and how do they compare to directly writing real code in more efficient programming languages with rich typesystems)? Are there development efforts where giving up and deciding that certain architectural elements are hard to change has been the right approach (in my experience it generally never is)? What are their names? Do they have experience reports? Are there numbers? I am looking for, at the least, a specific name like "The Chrysler Comprehensive Compensation System took these approaches to development." (But hopefully not a massive and expensive failure like C3.)
    - streetcat1 7y ago
      So you would not find any. You would need to judge those tools based on your specific use cases. Even if you find such and such project did X and got Y, the sample size is too small. The issue with software is that each project is different, and hence we cannot generalise from any given project.
traderjane 7y ago
geoftt isn’t asking whether metaphorical TLA+ is academically fruitful. He’s asking if Amazons et al. have _continued_ to use it, and whether there’s some volume of evidence attesting to this.
- streetcat1 7y ago
  Sure. So if amazon did not continue to use it. Does TLA+ suddenly become not useful? My point here is that those tools are theoretical CS tools based on the underlying nature of computers - which are a discrete digital state machine. Why do you even use high level languages, why not just program in assembler?
  - traderjane 7y ago
    If the Amazons of the world tried and dropped TLA+, that is signal to people who were on edge of technological adoption. If we received data on its efficacy during its trials, we'd be even more informed, as people are interested in more than the internal consistency of a system. Right now some people have a theory that Uncle Bob is noise in the sea of architectural opinion, and we can't move forward because we don't have enough data. The call for more data is welcome by me.
    - spenczar5 7y ago
      Amazon continues to use TLA+. I work there. It's not a tool needed every day, and it's not needed by everyone (really, not by almost _anyone_). But sometimes it's the best tool for the job. You won't be getting much data on this because companies are secretive. The way it's used is to ensure correctness of distributed systems. A classic example might be ensuring that a model for backing up customer data is unable to get into indeterminate state. It's important to get the model right. But the model isn't code - TLA is not a programming language, it's a tool for modeling state machines; yes, of course, one needs to also write software to deliver value.
  - geofft 7y ago
    > Sure. So if amazon did not continue to use it. Does TLA+ suddenly become not useful? Yes. (Or more precisely, it never was useful.) Zero part of my business requirements involve anything about discrete digital state machines. If I could deliver business value more efficiently with pen and paper, I would. If I could deliver business value more efficiently with Excel or a shell one-liner, I would (and do). If I could deliver business value more efficiently by singing my harmony into the Music of the Ainur, I would. I write software because it's the tool we've found that is most efficient at delivering business value, not because the software itself has value. So I use high-level languages because they are demonstrably more efficient. (And I frequently write sloppy code in Python or awk because it helps me answer business-relevant questions like "why is the site slow" quickly, without demanding I be rigorous about my software engineering in the process of answering the question.) don't use UML because I have yet to see evidence that it will help me deliver business value more effectively. (I do also enjoy writing software as a practice, and I do that on weekends. That's the time to make code for code's sake.)

deleted 7y ago

[deleted]

geofft 7y ago

That's, again, not what I'm asking. I'm not asking for the theoretical underpinnings of why this is a good way to represent 200-500 classes. I'm asking why, if I and two coworkers need to code up 200-500 classes by next month to meet a promise to a customer, spending time on UML will make the customer happier. I have a programming language that itself has strong theoretical underpinnings. I also have a pretty good hunch that in about two weeks there will be a last-minute requirement that changes the structure of the data model, and in about three weeks there will be a production outage of another system that distracts my attention. Will UML help me deliver software with changing requirements faster and more accurately? How does it compare to other options in my toolbox, like using a less verbose language that doesn't have real OO (which in my experience is often the right choice) and because of its conciseness is easier to make major changes to? How do I tie the UML object structure to my programming language, and why is it better than using a strongly- and richly-typed language in the first place? Why do I see many successful software projects that as far as I can tell don't use UML?

streetcat1 7y ago
First, I must say that the inventors of UML saw it as the last layer. The grand vision was a complete code generation from UML diagrams. And this was the overall grand vision that drove OO in general. I think that this is was happening now with the "low code" startups. The whole idea is to separate the global decisions (which are hard to change) - e.g. architecture, what classes, what each class do, from the local one (e.g. which data structure to use). So you would use UML for the global decisions, and than make programming the classes almost mechanical. Of course the customer do not see that. The customer see the user interface, and if the overall use cases are implemented correctly. Hence using those tool might help or not. Lets take architecture for example, why do people use an architect ?. Why does architect needs diagrams? Will the owner care of the architect use diagrams?
- geofft 7y ago
  Again, I am not asking how to use UML, or why the inventors of UML designed it in a certain way, or why it sounds like it could be a good idea, or whether there are other systems like UML that are good ideas (I can just use those systems directly then!). I am asking what evidence there is that UML helps me deliver better products more efficiently. Are there successful software projects that do this complete code generation thing (and how do they compare to directly writing real code in more efficient programming languages with rich typesystems)? Are there development efforts where giving up and deciding that certain architectural elements are hard to change has been the right approach (in my experience it generally never is)? What are their names? Do they have experience reports? Are there numbers? I am looking for, at the least, a specific name like "The Chrysler Comprehensive Compensation System took these approaches to development." (But hopefully not a massive and expensive failure like C3.)
  - streetcat1 7y ago
    So you would not find any. You would need to judge those tools based on your specific use cases. Even if you find such and such project did X and got Y, the sample size is too small. The issue with software is that each project is different, and hence we cannot generalise from any given project.

traderjane 7y ago

geoftt isn’t asking whether metaphorical TLA+ is academically fruitful. He’s asking if Amazons et al. have _continued_ to use it, and whether there’s some volume of evidence attesting to this.

streetcat1 7y ago
Sure. So if amazon did not continue to use it. Does TLA+ suddenly become not useful? My point here is that those tools are theoretical CS tools based on the underlying nature of computers - which are a discrete digital state machine. Why do you even use high level languages, why not just program in assembler?
- traderjane 7y ago
  If the Amazons of the world tried and dropped TLA+, that is signal to people who were on edge of technological adoption. If we received data on its efficacy during its trials, we'd be even more informed, as people are interested in more than the internal consistency of a system. Right now some people have a theory that Uncle Bob is noise in the sea of architectural opinion, and we can't move forward because we don't have enough data. The call for more data is welcome by me.
  - spenczar5 7y ago
    Amazon continues to use TLA+. I work there. It's not a tool needed every day, and it's not needed by everyone (really, not by almost _anyone_). But sometimes it's the best tool for the job. You won't be getting much data on this because companies are secretive. The way it's used is to ensure correctness of distributed systems. A classic example might be ensuring that a model for backing up customer data is unable to get into indeterminate state. It's important to get the model right. But the model isn't code - TLA is not a programming language, it's a tool for modeling state machines; yes, of course, one needs to also write software to deliver value.
- geofft 7y ago
  > Sure. So if amazon did not continue to use it. Does TLA+ suddenly become not useful? Yes. (Or more precisely, it never was useful.) Zero part of my business requirements involve anything about discrete digital state machines. If I could deliver business value more efficiently with pen and paper, I would. If I could deliver business value more efficiently with Excel or a shell one-liner, I would (and do). If I could deliver business value more efficiently by singing my harmony into the Music of the Ainur, I would. I write software because it's the tool we've found that is most efficient at delivering business value, not because the software itself has value. So I use high-level languages because they are demonstrably more efficient. (And I frequently write sloppy code in Python or awk because it helps me answer business-relevant questions like "why is the site slow" quickly, without demanding I be rigorous about my software engineering in the process of answering the question.) don't use UML because I have yet to see evidence that it will help me deliver business value more effectively. (I do also enjoy writing software as a practice, and I do that on weekends. That's the time to make code for code's sake.)