xml-dev - More chaos coming down the pike

["Mike Spreitzer" <spreitze@parc.xerox.com>]

Sun and the OMG are preparing to standardize two more arcs (XML schema
-> Java and XML schema -> OMG IDL, respectively) in an already large
and inconsistent graph of data modelling languages.  Below I have a
very partial listing of data languages and mappings between them.

I recommend (and have sent essentially this same message to the
responsible bodies) that new standardization efforts should take this
larger
picture into account, and strive for maximal consistency with the
explicit mappings and implied (via composition) mappings already
extant.  As the mappings already extant are not consistent, this
immediately tells us that new mapping standards should leave some
choices to an external "mapping choices" document.

A possible motivation for the XML schema -> OMG IDL mapping is the desire
to be able to easily import into the CORBA world standards already
developed in the XML world.  But it is also interesting to be able to
easily import into the XML world standards already developed in the
CORBA world.  This says that the XML schema -> OMG IDL mapping needs
to be *onto*, not just *into*, OMG IDL --- that is, it should be
possible to map some XML schema into any given IDL.  Similar
considerations apply to the XML schema -> Java effort.

While the "marshalling framework" of the proposed XML Data Binding
specification "is not in any way intended to displace the object
serialization mechanism that is already a central part of the Java
platform", perhaps it should be a generalization.  Another reason to
generalize Java serialization is that there is no inherent reason that
a given Java object should have only one serialization, which (as far
as I know) is a limitation of the current facility; I already have
heard colleagues complain that they want different serializations for
different purposes.


Languages that can model Data:

UML, OMG IDL, Microsoft IDL, Java, C++,
XML Schema:
    DTD,
    SOX <http://www.commerceone.com/solutions/xml/sox/sox.htm>,
    XML-Data <http://www.w3.org/TR/1998/NOTE-XML-data/>,
    XML-Data-Reduced <http://www.ltg.ed.ac.uk/~ht/XMLData-Reduced.htm>,
    DCD <http://www.w3.org/TR/NOTE-dcd>,
    DDML <http://www.w3.org/TR/NOTE-ddml>,
RDF & RDF schema,
SQL


mappings between languages:

Java<->bytes:

Java serialization
RMI-IIOP


Java<->XML:

XML Data Binding
<http://www.javasoft.com/aboutJava/communityprocess/jsr/jsr_031_xmld.html>

a hypothetical "Java archive" facility, mentioned in the XML Data Binding
JSR above

CommerceOne's SOX->Java mapping

IBM XML BeanMaker
<http://www.alphaworks.ibm.com/aw.nsf/techmain/98D0F921C80C8ED6882566F30070
3F7C?OpenDocument>

Coins <http://www.jxml.com/coins/index.html>

KOML <http://www.inria.fr/koala/XML/serialization/>


OMG IDL<->Java:

OMG Java->IDL
OMG IDL->Java


XML<->OMG IDL:

Forthcoming OMG Request For Proposals (from the ORBOS task force)


Microsoft IDL<->Java:

Microsoft


XML<->Microsoft IDL:

Microsoft SOAP / Userland XML-RPC


OMG IDL<->Microsoft IDL:

Chapter 18 in CORBA 2.3



UML<->IDL:

Rational Rose


UML<->Java:

Rational Rose


XML<->Database:

IBM's XPK4J
<http://www.alphaworks.ibm.com/aw.nsf/techmain/7B29BBCB9A1C1C1A882566F30070
3F83?OpenDocument>

IBM's DataCraft
<http://www.alphaworks.ibm.com/aw.nsf/techmain/12CD979739AB8E968825671B0065
A4A6?OpenDocument>


RDF<->XML:

W3C's XML-based syntax for RDF, in RDF spec
<http://www.w3.org/TR/REC-rdf-syntax/>


RDF schema <-> XML schema:

subject of debate in W3C


More than two sided:

WDDX <http://www.wddx.org/>
XMOP <http://jabr.ne.mediaone.net/documents/xmop.htm>



Mike Spreitzer <spreitze@parc.xerox.com>
http://parcweb.parc/spreitze/ (Xerox internal)
http://www.parc.xerox.com/spreitze/ (external)
+1-650-812-4833


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