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From Sebastien Chassande-Barrioz <sebastien.chassandebarr...@rd.francetelecom.com>
Subject Re: no-table => subclass-table: proposal for small change to inheritance strategy values
Date Wed, 16 Feb 2005 18:24:01 GMT
Hi,

Craig, sorry to be late...

What does means the value 'no-table' (or 'sub-class') ?

If the class is abstract then no value is required.
If the class is concret with two subclasses where are stored the
instances ? 
- in table of the first child 
- in the table of the second child
- both (how to choose ?) ;-)

This value can be understanding only in the case of a concrete class has
a single child. In this case it is simpler to define the table at the
top level instead of in the subclass ... So I think this value is
useless.

In Speedo internal (JORM), we use the following terminology which is
simpler (IMO):
- new-structure: redefine mapping of all fields, including inherited
fields
- added-structure: new table(s) are used for new fields only (not
inherited fields)
- extend-structure: parent tables are extended with new fields

Finally I am not sure the inheritance strategy has to be define by JDO
users. Indeed JDO implementations can analyse field mappings and compute
the inheritance strategy. The user only defines a column name from 
- the table defined at field level, 
- or the table defined at class level,
- or the table of its super class.

IMO the aim is to make simple .jdo files for users, not for jdo vendors.

Note: Maybe I am very tied and I forget something, in this case I should
go sleeping ...

Regards,
Seb

Le mer 16/02/2005 à 18:33, Craig Russell a écrit :
> Javadogs,
> 
> Unless I hear otherwise, I'm changing no-table to subclass-table.
> 
> Craig
> 
> On Feb 14, 2005, at 12:06 PM, Wes Biggs wrote:
> 
> > +1 for "subclass-table".
> >
> > Matthew T. Adams wrote:
> >
> >> Hi all,
> >>
> >> I was reviewing the last draft and wanted to suggest a small name 
> >> change
> >> to one of the values allowed for the "strategy" attribute of the
> >> "inheritance" element.  Currently, the three values are "new-table",
> >> "superclass-table", and "no-table".
> >>
> >> I propose renaming "no-table" to "subclass-table", as it is the 
> >> logical
> >> complement of "superclass-table".  "no-table" might confuse 
> >> (admittedly
> >> dumb) readers with 'persistence-modifier="none"', whereas
> >> "subclass-table" clearly indicates that fields are to be stored in a
> >> subclass's table as opposed to nowhere.
> >>
> >> I think "subclass-table" is more intuitive enough and make it
> >> **abundantly** clear to justify the change.
> >>
> >> Thoughts?
> >>
> >> --matthew
> >>
> >> Matthew T. Adams
> >> Corporate Technical Advisor & Senior Consultant
> >> Mobile:  +1 253 732 1051
> >> Phone:  +1 206 331 3833
> >> Fax:  +1 360 937 9616
> >> matthew.adams@xcalia.com
> >> P.O. Box 24163
> >> Federal Way, WA  98093
> >> www.xcalia.com
> >>
> >>
> >>
> >> Xcalia helps businesses address the challenge of Enterprise 
> >> Information
> >> Access in a heterogeneous environment.  We provide products and 
> >> services
> >> that facilitate the two-way exchange of information between 
> >> individuals,
> >> mission-critical applications, and databases.  Our customers enjoy
> >> improved performance, reduced operating and development costs, faster
> >> time to market, and rejuvenated legacy systems.
> >>
> >
> >
> Craig Russell
> Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
> 408 276-5638 mailto:Craig.Russell@sun.com
> P.S. A good JDO? O, Gasp!
-- 
Sebastien Chassande-Barrioz
Research & Development Engineer
France Telecom, Research & Development, MAPS/AMS laboratory
28 chemin du Vieux Chene - B.P. 98
38243 Meylan CEDEX - France
phone: +33.4.76.76.42.10 - fax: +33.4.76.76.45.57
email: sebastien.chassandebarrioz@rd.francetelecom.com
email: sebastien.chassande-barrioz@wanadoo.fr
GSM: 06.73.16.09.32

Try our JDO product: http://speedo.objectweb.org


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