ORM and O/R mapping

All of a sudden, people start blogging about O/R mapping, thanks to Steve Eichert. Thanks Steve! :) There is however a funny thing going on in some of those blogs: they use the term ORM.

O/R mapping is something else than ORM. O/R mapping is Object-Relational mapping, ORM is Object Role Modelling. ORM is also sometimes called the successor of NIAM and has its own website at: http://www.orm.net, run by prof. T. A. Halpin, once the researcher who developed NIAM with prof. G. Nijssen and others.

Now, do they relate? Well... in an ideal world, you should be able to use an ORM model as input for the code to generate/configurate by the O/R mapper: then you have both your relational model (abstracted via the E/R model for example) and the classes targeting this relational model. Visio for Visual Studio Enterprise Architect contains an ORM tool, which lets you design your abstract relational model and eventually generate DDL from it (and / or an E/R model).

This as a FYI while you're reading the O/R mapping articles about the pro/con aspects of O/R mapping.


  • I'd tend to disagree. I think that "ORM" is an overloaded acronym which - based on the context - either means "Object Role Modelling" or "Object Relational Mapping". I've seen it used in both meanings before ...

  • My pleasure ;-) I believe strongly in O/R Mappers as I'm sure you do too. Its nice to see so many people talking about them!

  • Thomas, charming as always!

    I'm lovin' it! ;)

  • Ingo: heh :) ok, that means OR not a lot of people use ORM (the modelling) (wouldn't be surpised) OR a lot of people use the wrong acronym ;)

    The point of my blogentry was that ORM (the modelling, geezz... because I have to say 'the modelling' proves my point ;)) is a term for Object Role Modelling, which doesn't have another name afaik. This means that to avoid confusion among developers, it's better to stick with the original terms.

  • Vincent & Frans: Agreed.

    I just wanted to support my point that I've seen it used with both meanings (a point with which Thomas didn't agree too much). The google.com query shows this as well and - just as I did - without any notion of whether this is right or wrong. It's just a snapshot of what people actually said.


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