Re: [xml-dbms] A basic question about XML-DBMS
- Dongling Ding wrote:
>DOMToDBMS supports updates and inserts. DBMSDelete supports deletes.
> I will look at DOMToDBMS and DBMSToDOM. But the reason
> for me to look at XML-DBMS is that it can support more
> types of actions comparing to others.
DBMSToDOM supports selects. That should cover everything.
> I still think XML-DBMS can combine some of propertiesCan you explain further? Note that part of the problem with v2 right now
> files together and have better structure to be
is lack of documentation, which will be written before the final
> > I still think XML-DBMS can combine some ofThe first thing I can think of is to combine action
> > files together and have better structure to be
> > understood.
> Can you explain further? Note that part of the
> problem with v2 right now
> is lack of documentation, which will be written
> before the final
and filter xml files together. In that case users only
need to manage one file instead of two.
Currently, the map file in XML-DBMS is DTD type. Do we
have a plan to move into XML schema compliant?
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- Dongling Ding wrote:
> The first thing I can think of is to combine actionI disagree here. Actions and filters are largely separate, so there
> and filter xml files together. In that case users only
> need to manage one file instead of two.
seems to be little advantage in combining them. Actions are used by
DOMToDBMS and DBMSDelete for inserts, updates, and deletes. Filters are
used by DBMSDelete and DBMSToDOM for controlling what data is deleted /
It would be possible to combine map documents and filters. The map
document is equivalent to join clauses in an SQL statement and the
filter document is equivalent to WHERE clauses. The advantage of this is
that it would probably be a lot clearer (I find filter files very ugly).
The disadvantage (and why I didn't do this) is that it would mean a lot
of duplicated information. For example, if you wanted two different
filters over the same set of data, all the map information would be
The real solution is to ditch maps, filters, and actions completely and
write an XQuery engine over JDBC. Don't count on this any time soon :)
> Currently, the map file in XML-DBMS is DTD type. Do weI'm not sure what you mean by "DTD type".
> have a plan to move into XML schema compliant?
1) If you mean that the map is validated by a DTD, then there is no plan
to change to an XML schema, as the DTD provides everything we need. You
can certainly do this yourself, as there are certainly tools to generate
an XML schema from a DTD.
2) If you mean that there is a way to generate maps from DTDs but not
from schemas, then there are plans to do this. Another user wrote a
MapFactory_W3CSchema class, but it works with an early version of 2.0
and I don't currently have time to update it.
3) Version 2.0 maps were designed with XML Schemas in mind and support
many of the constructs from XML Schemas. For example, the UseClassMap
element is designed to support complex types and the TokenList attribute
is designed to support enumerated types. The main feature of XML Schemas
that is not supported is inheritance of complex types. I had planned to
do this, but ran into technical difficulties.