Darien's Dialog..

Not so everyday professional doodles... from an Application Platform Solution Specialist, currently based in Microsoft Brisbane

"The impedance mismatch between object-oriented constructs and relational databases", A Survey by Darien Nagle

"The impedance mismatch between object-oriented constructs and relational databases", A Survey by Darien Nagle

  • Comments 8

So this is a classic problem that's always disturbed me (software engineering wise), and especially so on the .NET platform where Object/Relational mapping doesn't seem to be getting the due attention that I think it deserves. Not that there aren't persistence frameworks available out there, of course there are (Entity Broker, LLBLGen Pro, Wilson OR Mapper etc.. etc..). In fact, I'm so happy that Microsoft is working on ObjectSpaces; I just love the work thats been done there to date, even though we have to wait a little while before we can all play with it.

Its just that not a lot of .NET developers that I talk to even see the impedance mismatch as a problem. Everyone's just happy hard coding their object attributes directly to the database (we even encourage it somewhat in Visual Studio). And the very idea that I find this type of tight coupling a hideous violation of the software engineering principles of abstraction and maintainability, makes most developers look at me strangely. Hmmm. Maybe I need to get out more.

Nevertheless, for my dissertation (M.Sc in Software Engineering, title above) I'm bringing up the age old impedance mismatch topic again, in the hope of raising awareness, and checking on the state of the problem. Encouragingly, more people than I thought seem interested in 2004 (and even aware) than what I expected. I think there's definitely some ground swell taking place on the topic in the .NET community as a whole. Good stuff. It'll be a dream come true when your average VB developer can talk about their preference for persistence patterns and frameworks. Hopefully, we're not that far away from that day after all.

If you're a OO developer, and you've got an opinion on the object-oriented impedance mismatch, then I'd love to hear from you. I've set up a survey on my home page just for this purpose. Drop by and fill out this survey. If you do so before November 24th, I can incorporate your views into my final dissertation.

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  • I agree totally. Go Object Spaces!

    Good work for taking a step back and looking at things this way.
  • Really, that "brown font on black background" of your survey is very hard to read...
  • See my analysis of the problem: http://weblogs.asp.net/fbouma/archive/2004/10/09/240225.aspx
  • I have found that ORMs are a product that cause more problems than they solve. Sounds great on paper, but it just doesn't perform well. Very similar to OO where you have a very tall object hierarchy.

    Wally
  • Darien,

    best for your MSc project - I happen to be doing a final year project on my BSc Computing at Oxford Brookes University on the same topic... well, less of a thesis, though, and more of a hands-on .NET-based persistence framework design & implementation. I'm quite clear on the design but more or less for the sake of it, references to research are required which I'm desperate for. Apart from Scott W. Ambler, writings on the topic seem to be scarce. Anyone who wants to share their findings is welcome to email me!

    Good luck,
    Phil
  • Sorry for the delay in posting. Still buried in writing at the moment.

    @Alex: thanks for your comments. Yeah, I've been hanging out for ObjectSpaces since I saw it at PDC a couple of years ago. I really see this as a step in making OR mapping mainstream (in thought and technology)

    @Uwe: Yep, agreed. Actually I set my website as a music production site originally, so it's supposed to be 'artistic', but not really relevant for a survey.

    @Frans: Thanks heaps for noticing my blog. I feel quite honored. :) Your article is excellent, and is an excellent reference. Would love to see you write some formal papers and present your thoughts. Academia could well do with your excellent input (and experience) on this topic. :)

    @Wally: really interesting comment. If you've got time, I'd love to know more about your experiences. Feel free to fill out my survey and share your thoughts there.

    @Philip: Good on you Philip! Great to find someone else who finds this topic relevant and interesting. Yes, Scott Ambler's works from 2000 onwards feature substantially in my dissertation. As you've discovered, he's got some great things to say (IMHO) about the topic and really has a practicle viewpoint that I appreciate. Having said that, lots of other writers have plenty to say about the impedance mismatch in general, including such substantial authors as C.J.Date, but you have to dig. When I'm done with my dissertation (few weeks time), you may look at my work (and references). Just email me directly if you would like a copy. Good luck to you too!

    Darien
  • Nice site.

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