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From Stefano Mazzocchi <stef...@apache.org>
Subject Re: XML Database
Date Fri, 07 Jul 2000 12:12:28 GMT
Francois Wirth wrote:
> 
> Hi,
> 
> Just want to know if anyone considered developing an XML driven database
> like Tamino. I would be nice to work on an open source database that uses
> Xerces, Xalan etc. for the XML processing. I know this is a huge project,
> but I think there could be a lot of uses for this database and it would be a
> challenging project. It could just be based on XML technology XQL, Soap, XML
> Shemas etc.
> 
> What do you think?

almost everybody in the Java/XML world, sooner or later, happen to
think: placing objects or trees in a relational database is a pain in
the ass. It's like mixing apples with oranges.

DBMS research created OODBMS along with things like ODMG, object
oriented query languages and such. Another derivation is EJB.

Now we have tree-stuctured documents.

Suppose you have a million XML pages, these are you data, you content.

The nice thing about trees is that you can add nodes at will, the nice
thing about namespaces is you can have multiple dimensions without
worrying on name collisions.. and XMLSchema still being able to validate
them.

So, you have n documents and you do

 <xdb:database xmlns:xdb="http://xml.apache.org/xdb">
  <xdb:section xdb:title="documents">
   <xdb:tree xdb:uri="...." xmlns="...">
    <page>
     <title>this is one article</title>
     ...
    </page>
   </xdb:tree>
   ...
  </xdb:section>
  <xdb:section xdb:title="news">
   <xdb:tree xdb:uri="...." xmlns="...">
    <news title="ASF starts an XML database">
     blah blah
    </news>
    ...
   </xdb:tree>
  <xdb:section>
 </xdb:database>

this is the XML "dump" of your database while, internally, it should be
able to do special indexing to optmizize queries and all that, just like
any DBMS does.

What do you use as a query language?

Possible usages are:

 - xpath
 - xpointer
 - xql

XPointer extends XPath with ranges (which might be very useful in this
case), but is only for "pop data", nothing to "push data".

XQL will sure add the notion of "joins" "insert" and all that but I
don't have ideas on its status.

Anyway, yes, something like this is _incredibly_ important indeed.

> What is the possibility of this happening?

I have been talking to Falko of the Infozone-group
(www.infozone-group.org) about joining efforts on this side. They have
created a project called "Prowler" which is a content management system
based on XML and on their OODBMS system called "Ozone".

While they have a GPL-like license, they already agreed on changing this
to the Apache license and move their community on this project. At this
point, it's just a matter of deciding what to do.

I want to be entirely honest with you as I was to the Infozone people: I
don't picture prowler as the end, but as the beginning. A way to
"catalize" a community around the problem of XML content management
(with versioning, authorization workflow and all that).

Of course, I see lots of uses of Prowler both from the Cocoon project as
well as independently as it stands now, but I see a bright future of
something like this since it covers a particular aspect of XML that we
do not yet cover and I believe very important.

I'm happy you started this discussion so that now I can see your
comments about this.

Again, this is open development: the fact that we start with some code
is _NOT_ to "stamp" a project with the Apache quality label, but to fuel
innovation, increase visibility and accelerate development.

And since I (rather egoistically, I admit :) need such technology, I'd
rather see it happening here with the Apache spirit rather than
somewhere else.

What do you think?

-- 
Stefano Mazzocchi      One must still have chaos in oneself to be
                          able to give birth to a dancing star.
<stefano@apache.org>                             Friedrich Nietzsche
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