Mostly just wanted to archive this on FoRK and dist-obj, but I had some
incidental comments to offer too ...
At 01:41 AM 8/22/99 -0700, you wrote:
>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.
Absolutely. I hope you're planning to contribute to the JCP!
Luckily, surjection is already a goal.
>
>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.
Just to be clear, there is no XML Data Binding specification at this point
in time, just a strawman discussion paper to kickstart a JCP.
> 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.
The 1.1-based JDKs support a single serialization (java.io.Serialization)
mechanism at as you point out, but luckily it's mildly extensible via
java.io.Externalizable - perhaps not ideally so due to the lack of
implementation MI, but close enough.
Still, there's some value in a single format. Without it, I have to worry
about dynamically loading in the code necessary to reconstitute the object
graph when I stumble upon it. Does the cost of the need for variety in
formats outweigh the value of at least declaring a de-facto standard? I
personally don't think so, and therefore appreciate that Java has a single
format (even though I wish it were something else).
>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
It'd be nice to see a full blown survey of the above. Anybody know of any?
Got any plans to update "Towards a Web Object Model"[1] Frank? 8-)
[1] http://www.objs.com/OSA/wom.htm
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