[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: Storing Lots of Fiddly Bits (was Re: What is XML for?)
At 31 January 1999 20:33, W. Eliot Kimber wrote: > [In response to Mark Birbeck] > But you've not solved my problem, because the in-memory > abstraction of the > *document* is still: > > (xml-document > (data-instances > (element > (gi "person") > (content > (element > (gi "name") > (content > (literal "Eliot"))))))) > > So, while the result is closer to the abstraction of the > data, it is still > not the original abstraction. True. But I could have said: <person oid="1" name="Eliot" sex="male"> <employer oid-ref="2" /> </person> <enterprise oid="2" name="ISOGEN International Corp" address="Dallas, TX"> <derived obj="employs" oid-ref="1" /> </enterprise> if that was a better model of the internal data. Maybe I've missed the subtlety of what you are saying the problem is, but in our system the attributes of an object are exported as described above, and the children of an object are exported as elements within other elements. Seems to me to mirror exactly our object structure - and so far we have been able to re-interpret DTDs back as data definitions. In other words, we *can* generalise the solution. > And note that even for an early-bound form, there are still > infinitely many > ways to construct it I still don't follow your logic - just because there are many ways to construct it, doesn't mean you can't construct it. > So no matter how you slice it, there will always be a > disjoint between the > abstraction of the serialization form and the abstraction of the data > objects being serialized, which means that a query onto the > abstraction of > the serialization will not be the same as a query onto the > abstraction of > the data that has been serialized. The gap might be bigger or > smaller, but > there will always be a gap. Sure. But I still have two issues. First, why would you query the serialisation anyway? Wouldn't you want to query your original database and generate XML pages that reflect the results? Even if you have serialised the data to XML files to speed up the movement of data, you would still want to do searches against the original data. (The nice thing about that - as a little aside - is that you create XML pages that are 'results' pages, ready for the user to drill down through, using whatever super-duper, 3D-helmet, speech-activated interface they have access to.) But second, and I think the main point, I don't understand why you are distinguishing between the XML representation of an object and its serialised form in the way you do? Why not just serialise and de-serialise between XML and the database? I know you ARE doing that, but the XML you are creating is some sort of 'normalised' representation of the original data. You keep talking of the 'abstract' representation of your data, but actually you are *losing* the abstraction, moving from: a person who has the name Eliot to an object which contains another object which has two properties, one set to name and the other set to Eliot Of course both are abstractions, but they model completely different things (data and people). And modelling the data rather than the person means you can no longer interchange your XML with other systems because you have two completely different sets of data, using different DTDs. (And you can't say that your serialisation schema *will* allow this interchange, because although your serialised data may be well-formed, the underlying data it represents may not be, so you need the proper DTD for the object.) > Which begs the question: if the abstraction of the document is not the > abstraction of the data, why bother to create and store the > abstraction of > the document when you can just as easily create and store the > abstraction > of the data? All I am saying is that the document *itself* could be the abstraction of the data. Anyway ... if I've missed the plot then I look forward to your clarification, since we are dealing with similar issues here. Regards, Mark Birbeck Managing Director Intra Extra Digital Ltd. 39 Whitfield Street London W1P 5RE w: http://www.iedigital.net/ t: 0171 681 4135 e: Mark.Birbeck@i... xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i... Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ To (un)subscribe, mailto:majordomo@i... the following message; (un)subscribe xml-dev To subscribe to the digests, mailto:majordomo@i... the following message; subscribe xml-dev-digest List coordinator, Henry Rzepa (mailto:rzepa@i...)
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