Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!gem.mps.ohio-state.edu!wuarchive!psuvax1!psuvm!uh2 From: UH2@PSUVM.BITNET (Lee Sailer) Newsgroups: comp.software-eng Subject: Re: Information Systems is an Engineering Discipline Message-ID: <89277.091206UH2@PSUVM.BITNET> Date: 4 Oct 89 13:12:06 GMT References: <1142@svx.SV.DG.COM> <34399@regenmeister.uucp> <5296@eos.UUCP> Distribution: comp.edu Organization: Penn State University Lines: 24 > I agree that verbal descriptions cannot be good >enough. Pictures are better (data flow diagrams and the like) but they >aren't models, they can't be easily tested. There must be something >we can use. Suggestions? Opinions? I think DFD's are models, though you are right that the testing is problematic. The test is called a "walk thru." Some procedures (or perhaps better, guide- lines) have been developed that make some walk throughs more effective than others, and some people are better at it thena others. "Verbal descriptions" can be models too, especially if they are in languages like PDL, or structured English, or whatever. The final source code is a "verbal desription" is it not? That is, I can verbalize it over the phone to you, and you can write it down, and then you know more about the system than you used to. However, I didn't write this to quibble about whether these are models or not. I wanted to point out that models are reductions of the actual system, and by definition they omit some detail. It is usually necessary to build two or three different models of the system, using differnt modeling tools, in order to get a well rounded view of how the final system will behave. lee