Tools To Automate Checking of Software Design

heck writes "Scientific American describes some of the work to develop tools for examining the design of software for logical inconsistencies. The article is by one of the developers of Alloy, but the article does reference other tools (open and closed source) in development. The author admits that widespread usage of the tools are years away, but it is interesting reading the approach they are taking regarding validation of design."

Comments

too hard.

[yagu]

Back in the mid-80s I attended a seminar in Atlanta, it was about automated software engineering... and tools and workbenches that would take as input specifications and design parameters and would crank out entire suites of software/applications. (Heck, there was even a new acronym for it, can't remember what it was, but it was a hot, hot, hot button for a few years.) We were pretty much warned our careers were over, automation was here to generate what we as professionals had studied years to create.

It never happened. It never came close to happening. We are as far away today or further from tools that can generate applications transcendentally.

I was skeptical then, I'm skeptical now. Tools like the ones described are useful, but they're not foolproof, and they hardly supplant the intuition and "art" that is programming.

At best tools are an adjunct to the software development process, not to be a replacement for common sense testing and design and code walkthroughs. I could construct many scenarios that logically would be consistent but have no relationship to the desired end of the application, i.e., a logic consistency tool would not detect a problem. Any poorly designed system with these "new" tools applied will merely be rigorously poor systems.

As for the prime example (in the Scientific American article) of the Denver International Airport baggage handling debacle, I doubt logic analysis tools would have had much impact on the success or failure of that effort. I knew people involved in the project, and "logic consistency" in their software was the least of their problems. (I would have loved to been on a team to design and develop that system -- I think it was a cool concept, and ultimately VERY feasible... )

I did get one benefit from the Atlanta Seminar -- I got a football signed by Fran Tarkenton (he was CEO of one of the startup companies fielding a software generating workbench).

Re:too hard.

[AuMatar]

UML is snakeskin oil in and of itself. Yes, its occasionally useful to draw a diagram. Yes, a simple common syntax for those can be good. But thats about all its useful for- designing in UML is a joke (it just doesn't, and never can, portray all the information that text can) and automatic code generation is even more of a joke (at absolute best, it saves you 5 minutesof typing boilerplate class skeletons).

Re:too hard.

[Anonymous Coward]

I agree completely with the code-generation ... it's useless.

When I was young, stupid and without real-world experience, I also thought UML was crap. However, once you realize that the point of UML is not helping to design, but helping to communicate the design to other developers, it becomes useful (not ground-breaking, not amazing, not neccessary, just useful).

It's like that: when you design a piece of software alone, you can use whatever system you want to model it (keep it all in your memory, write class-structure as pseudo-code etc.). If you need to communicate your design to others, it's good to have a system with defined semantics to formulate the design (visualization is not even the issue here), and one such system is UML; surely not the best, but one that a sufficient number of developers (software engineers, not programmers) are trained to understand.

Lacking such a system of communication, you would first have to explain the meta-model (explain how the description of your design is to be understood) instead of just explaining the design-model itself.

Re:too hard.

[deathy_epl ccs]

at absolute best, it saves you 5 minutes of typing boilerplate class skeletons

The code generation from UML is only supposed to be the class skeletons, and I've got to ask... have you never written an application with more than a handful of classes? The time spent just building the skeletons for some of the applications I've written over the years has taken a helluva lot longer than 5 minutes.

I personally find class diagrams darned useful. I also find use case diagrams useful not because they help the programmer, but because they help to make sure that we correctly understand what the user is asking for.

From reading your post, though, I'm not entirely certain you have actually bothered to learn UML before you started to slam it. You say:

it just doesn't, and never can, portray all the information that text can

Anybody who knows UML knows that an incredible amount of the work is done in text. Sure, you can create state and activity diagrams for your use cases... or you can just attach textual documentation that is typically easier to create and much smaller than state or activity diagrams. This is what you are typically ENCOURAGED to do for anything but the most convoluted process... and when you have a very convoluted process, even text fails.

There are times that it is very useful to have pictures with circles and arrows and a paragraph on the back of each one.

UML is not the best solution for every development project, for very large projects with lots of developers involved, it can certainly make life easier.

Finding Nemo Architecture

[Anonymous Coward]

This reminds me of my previous job. One day the owner of the company came up with a brilliant idea. He had just watched the movie "Finding Nemo" and asked me, "have you ever seen finding nemo? You know those little silver fish? I think we should design a system based on those little silver fish. If we get enough small components they can be combined into any piece of software. Eventually we wouldn't need any more components and thus no more software developers. All of our software would be made by sales guys who could just combine these components into any software we need." I remember thinking to myself that we could just start with quarks and we could build everything in the universe. But I didn't say anything and was just happy to not be chosen to be on the team creating the silver fish.

6 years later, dozens of programmers, and millions of dollars, the finding nemo architecture has been a bust. The owner of the company refuses to give up on the idea. They currently have created components of "and" and "or" gates and use "wires" to put them together. It reminds me of entry level electrical engineering. Back before they tell you that writing software on flash is usually easier and cheaper than wiring together dozens of IC's. In any case, I eventually did get sucked into the project and promptly left the company.

Re:Finding Nemo Architecture

[TapeCutter]

"If you can just download a library that can do X, write a bit of glue code, and be done your productivity has skyrocketed."

When I worked for IBM in the 90's the CEO made the pronouncement: "All code has been written, it just needs to be managed". We all thought he was clueless, nevertheless here I am 10yrs later writing "glue code" for somebody else and IBM is still the largest "software as a service" company on the planet.

Good Software Design

[KidSock]

A good design correctly models the concept of what it is you're trying to achive with the program. Ultimately this means the programming interfaces (APIs) for each concept are correct [1]. Don't design interfaces around procedures. Don't design interfaces around the physical world. Design to *concepts* and *ideas*. This is superior because you will never discover at a later time that the code is fundamentally flawed and needs to be totally re-written. If the interface correctly models the concept, by definition, it CANNOT be wrong. If it is wrong then you simply didn't understand the concept well enough or you failed to translate that concept into a suitable interface and you just need to think more and type less. If you do get things right you'll find that major peices dovetail together perfectly [2]. The implementation can be wrong and may need to be re-written but if the interface correctly represents the concept the re-write will be localized to one library or part of a library. That is a much more straight forward matter than using a bad design and finding half way through a project that the required changes transcend the whole system.

And thus you cannot validate a design because that would require representing a concept and determining if an interface suitably models it. That is HARD. If that were possible you would effectively have a thinking, rationalizing, brain (Artifical Intelligence) in which case you wouldn't be dorking around with validating programs, you would be dynamically generating them.

[1] Frequently people advocate that interfaces are "well defined". That just means there are no holes in the logic of it's use. Personally I think a well defined interface is useless if it does not correctly model a concept. You can always go back and fill in the holes later.
[2] Although this is also when you discover that you didn't get the concept right and need to adjust the interface (hopefully not by much)

Formal Modeling/Model Checking

[aeroz3]

The point of these tools, is to simply verify the consistency of a design, not to execute or examine existing source code. The steps involved are:
1) Come up with software design
2) Implement software design in one of these tools (model it in Z, or as a state machine using fsp/ltsa)
3) Use said tool to verify the consistency of the design.

Now, this activity, of course, takes a lot of time, and is unlikely to ever be of any use to your average J2EE/Ajax/Enterprise application. Areas where they CAN be of use are in things such as life-critical systems. For instance medical devices, or air plane control systems. Using something like FSP/LTSA you can model, check, and verify that your design does not every allow the system to enter into an invalid state. Now, remember, this says nothing about the final code, there is a separate issue of the code not matching the design, but it is possible to verify that the design does not ever lead to invalid states.