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Simon Willison’s Weblog

Click Maps

I’m not a very visual person; complex entity relation ship diagrams, data flow diagrams and the like are usually completely lost on me, and I try to avoid them when they are mandated by coursework at University. Give me a text based SQL schema any day. Click Maps on the other hand I could learn to like—they’re nice and straight forward and solve the very real problem of planning how different parts of a web application will link to each other.

Posted 14th November 2003 at 2:02 am

This is Click Maps by Simon Willison, posted on 14th November 2003.

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10 comments

  1. It's worth getting over your difficulties with such diagrams if you ever want to develop complex applications. If you have dozens of tables and a similarly large number of classes, it's almost impossible to keep track of things except through diagram.s

    Rich - 14th November 2003 12:36 - #

  2. I'll have to take your word for it. I think the problem is that I've only ever worked on small to medium szed applications with less than 20 tables so I've never had the need for diagrams. What's more, the university projects where we are asked to use them are generally much smaller than that so the time spent creating the diagrams ends up feeling wasted as they don't add anything to my understanding of the application.

    Simon Willison - 14th November 2003 16:09 - #

  3. Are you using software to manipulate the diagrams? At work, I use Visio, which is a moderately pleasant way to do this sort of stuff (including reverse-engineering existing databases and websites automatically). It won't export diagrams as SVG images though, alas. I can't believe I just said something nice about a MS product. I really should investigate open source alternatives, I suppose...

    Rich - 14th November 2003 17:46 - #

  4. Dia is quite a nice alternative. Not sure it reverse-engineers anything automatically, but it still works quite well. The Windows port isn't fantastic, but it's still OK ... I'd recommend you try it at least once. I agree with Si that often the diagrams seem to take rather a long time to add little value. On the other hand, though, they can often help communicate to those group members who don't have a full understanding of the workings of the system -- which can be a really good thing. I particularly found the CRC cards helped in this regard.

    Meri Williams - 14th November 2003 17:59 - #

  5. I just installed Dia, and although the Windows port isn't great it does export SVG *beautifully*, at least compared with my previous Visio -> OpenOffice -> SVG path. Thank you so much.

    Rich - 14th November 2003 18:27 - #

  6. The biggest app I support has about 100 tables, and way, way too few classes.

    A couple years ago, someone on the team took a few days to make a ER diagram of the relatively-stable schema. I am quite sure his time was repaid within a month. And the benifit continues.

    Quite surely, many IT shops err on the side of voluminous documentation, and yet don't get much value from it.

    I'm an agile proponent, and certainly, when someone asks for a doc, I ask what it's purpose is-- but sometimes, there's a legit need.

    t's awfully hard to see the benefit of, say, iterative development and heavy customer involvement when you've only got one due date for a well-defined project.

    I think CS academic programs are often quite poor at presenting what can actually be expected in a career as a developer. I think the industry would benefit from an internship (nee apprenticeship) program. I imagine that you're kinda doing that now, Simon. :)

    Jeremy Dunck - 14th November 2003 23:29 - #

  7. I second Jeremy. The latest CMS I worked on had "only" 52 tables but we did the database & classes diagrams. When some developers joined us several months later, all they had to do was to talk with the project manager or a developer during 1-2hours to learn how the things globally worked and then dive in the diagrams to learn more precisely the anatomy of the parts they had to touch.

    One of the devs was a little extremist to me, and did some UML diagrams of his classes and methods. He spent many ( too much ? ) time to do them but he had really few bugs and when he had some he quickly found them.

    AFAIR we used MagicDraw and Visio to do our diagrams

    P01 - 15th November 2003 01:36 - #

  8. Rich, glad you liked Dia and found it useful. I believe they're still putting some effort into the development of the version to run on Windows. It's been steadily improving since I first started using it for ER and UML diagrams for software projects last year.

    Meri - 16th November 2003 19:00 - #

  9. You can see some of the first fruits of my involvement with Dia at http://www.theculture.org/rich/sharpblue/images/ma psofphysics.html (which is still a first draft so far).

    Rich - 16th November 2003 22:30 - #

  10. Postscript: You'll need an SVG-capable browser, which rules out Mozilla for Windows and possibly others too.

    Rich - 16th November 2003 22:31 - #

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