AW: [Objectbridge-developers] [Fwd: [objectbridge - Open Discussi on] New repository.xml/dtd proposal.]

[Mahler T. <tho...@it...>]

Hi again,

> -----Urspr=FCngliche Nachricht-----
> Von: Ivan Toshkov [mailto:to...@cr...]
> Gesendet: Mittwoch, 29. August 2001 10:13
> An: Thomas Mahler
> Cc: Iv...@ho...; objectbridge
> Betreff: Re: [Objectbridge-developers] [Fwd: [objectbridge - Open
> Discussion] New repository.xml/dtd proposal.]
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> On Tue, 2001-08-28 at 21:40, Thomas Mahler wrote:
> > Hi Ivan,=20
> >=20
> > Thanks for your proposal. It's really an improvement to the old =
DTD!
> > Very well done!
> > I have some minor remarks which you find below.
> >=20
> >=20
> > > Subject: [objectbridge - Open Discussion] New repository.xml/dtd
> > > proposal.
> > > Date: Tue, 28 Aug 2001 07:34:38 -0700
> > > From: no...@so...
> > > To: no...@so...
> > >=20
> > > Read and respond to this message at:
> > > http://sourceforge.net/forum/message.php?msg_id=3D221783
> > > By: core
> > >=20
> > > Hello,
> > >=20
> > > Here is a proposal for new repository.xml and DTD based on the
> > > discussion, which
> > > took place in the mailing list.
> > >=20
> > > Unfortunately, there are some problems with my email=20
> provider, so I may
> > > be not
> > > aware of all the recent posts.
> > >=20
> >=20
> > I posted your proposal to the mailinglist, so that evryone=20
> listening may
> > comment on it.
> Thanks. The mail servers seems to operate normaly again :)
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> > > The changes are as follows:
> > >   1) Decoupling the repository to the following top-level=20
> elements:
> > >   jdbc-connection (formerly ConnectionDescriptor),
> > >   table (formerly part of the ClassDescriptor),
> > >   class (formerly part of the ClassDescriptor) and
> > >   class-extension (formerly ClassDescriptor/ExtentDescriptor).
> > >=20
> >=20
> > I'd prefer to call it extent, interface or class-extent rather than
> > class-extension.
> Ok, I'll change that.
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> > >   2) Put all the data in attributes, instead of as text.=20
> This is useful
> > > because
> > > the DTD can describe the attributes better than the text (e.g.
> > > enumeration of
> > > values) and it's easer to write SAX  parser, because you=20
> can do most of
> > > the
> > > work in the  start event, rather than the end.
> > >=20
> >=20
> > I agree. The main reason why I started with an element=20
> oriented DTD was
> > that I thought it would be easier to read for humans. But I=20
> think your
> > grammar is at least as readable as my original version!
> >=20
> > >   3) Changed the naming convention to something, which=20
> more closely
> > > resambles
> > > the one used by W3C.
> > >=20
> >=20
> > It's quite clear to read. What I liked with my old DTD was that the
> > element names (say "ClassDescriptor") corresponded with the=20
> respective
> > classes that were instantiated by the parser.
> > But that's not a real argument...
> Well, nither is mine. I wanted one naming convention and I'm=20
> quite used
> to the one I proposed, so this is the result.
> >=20
> > > One of the remaining issues is the element, formerly=20
> known as (prince?
> > > ;)) `deciptor_ids'. It  contains a space separated list=20
> of foreign key
> > > references.
> > > I don't know if this should go to the new `table' or=20
> `class' elements.
> > >=20
> >=20
> > Actually the descriptor_ids were referencing the=20
> fielddescriptors of the
> > "other" class. Thus we have to use names that identify the=20
> respective
> > field element.
> > For example:
> >    <class table-ref=3D"Kategorien"
> >           name=3D"test.ojb.broker.ProductGroupWithTypedCollection">
> >      <field column=3D"Kategorie_Nr" name=3D"groupId"/>
> >      <field column=3D"KategorieName" name=3D"groupName"/>
> >      <field column=3D"Beschreibung" name=3D"description"/>
> >      <collection item-class=3D"test.ojb.broker.Article"
> >                  name=3D"allArticlesInGroup"
> >                 =20
> collection-class=3D"test.ojb.broker.ArticleCollection"
> >                  auto-retrieve=3D"yes"
> >                  auto-update=3D"yes"
> >                  auto-delete=3D"yes">
> >        <ref-id id=3D"productGroupId"/>
> >      </collection>
> >    </class>
> >=20
> > where the 1-n relation between ProductGroup and ARticle is=20
> maintained by
> > the foreign key attribute productGroupId in class Article:
> >    ...
> >    <field column=3D"Kategorie_Nr" name=3D"productGroupId"/>
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> Yes, I was too lazy to change this. Actually, I've generated the XML
> from the old one with an XSL (which can post here, once the XML
> structure is finalized) and fixed some of the problems=20
> manually. Then I
> used JBuilder 5, which can create a DTD from XML and again=20
> fixed *some*
> of the problems manually.
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> What bothers me with descriptor_ids is that it seems important in =
both
> class and table elements.  In table it will be used to generate the
> foreign keys and it should reference to column names. If its in =
class,
> it should use field names.
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> I don't know OJB internals, so I don't know if we can eliminate the
> second choice, so perhaps I should eliminate the first one=20
> (as it is in
> the proposed xml).
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ojb depends on the proper reference to the class-attribute descriptor! =
Of
course it would be better to have this information only in one place.


Thomas

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> --
> Ivan
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