Re: Short Essay: Squeezing RDF into a Java Object Model
David Megginson wrote: > Obviously, there's a much more complex model underlying RDF than the > spec lets on, and that model affects not only the ease or difficulty > of implementing an object model, but also the difficult of many > standard operations like queries against a collection of RDF > statements and storage in a relational database. May I respectfully submit that the problem is not the complexity of the model underlying RDF, but its simplicity and relative freedom from restriction, permitting the very sort of extension that leads to the implementational problems David Megginson illustrates. Or, stated from the opposite perspective, obvious real-world implementations of RDF build upon the assumption that the standard specifies, or at least implies, a more holistic view of metadata than it does. The unfortunate truth is that implementations of RDF--even as they grow step-by-step as complex as David Megginson illustrates--never model anything more than individual resources: they do not, even as a by-product, model the body of modeled resources as a whole. Effectively it is just such a cumulative body of metadata which David Megginson is seeking. It would provide the ability to refer to components larger than simple subjects, predicates and objects, such as resources as objects or prefixes as subjects. Such a framework would comprehend and permit reference to any such objects either top-down, from the perspectives of their larger containers, or bottom-up from the perspective of their sub-components. In fact, it appears that this inability to implement the innate human assumption of a larger framework, not specified by the simple details of RDF, is a shortcoming not just of RDF but of structured markup generally. Recent debates on this list about the unification of XSL and XLink revolve around symptoms of the same problem. The increasingly centrifugal nature of the whole body of XML standards could reasonably be described as the failure of building upon the details to produce as a by-product a framework which multiplies the interconnections and the interdependence among them. My own work is in implementing a database engine which operates directly upon XML markup. Its first premise is that XML markup describes, primarily, structure and that manipulating XML documents on their own terms means managing them on the terms of whatever structure the instance markup describes. From my (hardly disinterested) perspective, it is this ability which David Megginson seems to be wishing for in describing the implementational difficulties of RDF: if, for example, an object is a resource, it should be manipulable as either (and both) an object and a resource. Implementation of the simple details of RDF will not provide that, but database tools which can operate on structure described by XML markup, to whatever level of complexity, can. As David Megginson's examples illustrate, the implementation strategy implied by RDF (and other XML specification) details is agglutinative, an inherently linear process. We need implementation tools--and not just for RDF--which are also agglomerative, building a larger ball or sphere of interconnected structure from the details of instance markup as it is processed. Walter Perry 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/ and on CD-ROM/ISBN 981-02-3594-1 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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