[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Relational Tables and structured document
I've been following the comments about using XML as a database, and I have a question -- The discussion of ODMG and using XML as a database suggests that you will be able to update the database. But, if you have a large XML file, how do you update fields within that file without copying or re-writting the whole file? That sounds very awkward. Or am I missing a step in this process? Are we assuming that the XML file has been [expletive deleted] into an OODBMS such as one for which there are ODMG language bindings? I think this would be very powerful. However, it is no longer XML, is it? Or is the goal to store the data in a RDBMS or OODBMS and then export it to XML so we can send it across the wire and around the Web? I guess I am asking whether there is a model this kind of use of XML as a database. Dave > Peter Murray-Rust: > > >I have been spending the last two weeks working on a molecular application > >which essentially consists of relational tables. The application is > >largely hierarchical (a protein molecule) so that it benefits from being > >recast into structured document form. I have therefore found it useful to > >create routines which generate nodes in a tree as a result of joining > tables. > > > I think there are several things that one could usefully do. > > (1) define a recommended way of representing a relational table in XML. > (There > are a number of ways of doing this, the biggest decision is whether to use a > standard DTD for all tables or a DTD that reflects the specific table > definition.) > > (2) extend this to a richer data model, e.g. the nested relational model, > that > allows you to represent hierarchic structures, or the ODMG model which > allows > to to represent arbitrary graphs. (Note that the problem then becomes > analogous to the one of using XML as a serialisation format for CORBA > objects) > > (3) provide a toolkit that allows you to perform transformations on these > XML > documents that reflect the operators of the relevant data model, e.g. > relational > selection, projection, and join; sorting and grouping; flattening of nested > relations. > Of course one way to implement such operations would be to load the data > into > a database, but many of the operations can be implemented directly without > too > much effort. > > I think the key thing is to keep the set of structures and operations very > clean: > base it on a data model with an established formal basis rather than > inventing > something new. > > Mike Kay, ICL > > > 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...) > > > 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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