On Saturday, Nov 1, 2003, at 17:57 America/Detroit, Bob Wyman wrote:
> A call for fairness and equal rights...
> Now that X.694 has been approved, ASN.1 based systems can generate and
> consume just about any XML object that can be defined using XML
> Schema. Thus, there seems to be no reason why ASN.1 wouldn't be
> considered to be just as much an "XML Schema Language" as any of the
> other more well-known languages like XML Schema, Relax NG, Schematron,
> etc. Yet, of hundreds of sites and many books that include lists
> and/or discussions of languages for describing XML schemas, virtually
> none mention ASN.1... This doesn't make sense to me.
"Just about any XML object" may be the operative phrase here. Can
ASN.1 systems handle mixed content and open content models, e.g. XHTML?
I was under the impression that ASN.1 could model strongly typed,
regularly structured XML but haven't heard anyone advocate it for more
content-oriented, document-like uses. If it can, some advocacy, and
especially demonstrations of what concrete advantages ASN.1 might offer
in specific circumstances would help spread the word.
> It seems to me that responsible writers would include references to
> ASN.1 as an XML schema language. If ASN.1 was limited in its ability
> to describe XML objects,
This gets into another point -- there is a widely-held belief by many
(most?) XML developers/analysts that XML *is* a text markup format, so
"XML objects" is an oxymoron. See
http://lists.w3.org/Archives/Public/www-tag/2003Oct/0036.html for the
most recent outbreak of the long running debate on this point . (Note
that I personally am on the "you also need a data model" side, but that
doesn't mean that I'm ready to accept ASN.1 as an "XML" technology!).
>
> Given that ASN.1 is now capable of fully describing XML objects, it
> should be included in all lists of "XML schema languages." And, we
> should put to bed the now mute discussion of "Binary XML." XML should
> stay in the realm it started in -- a text-based language for tagged
> data exchange. The problem of binary exchange is handled well by
> others...
>
Now I'm confused: If ASN.1 is an "XML" technology, isn't it a "binary
XML" system, that is, an alternative Infoset with a range of possible
serialization formats?
I'm probably more sympathetic to alternative serializations of the XML
Infoset than most people on this list, but I'm far from convinced that
ASN.1 is a useful part of the XML suite of tools. One exception would
be in very limited circumstances where there a tight coupling between
components of an application, a strong use case for XML Infoset-tools
such as SOAP, DOM and XSLT, but for some reason XML itself is too
inefficient in the application context. I can imagine that occurring
in certain Web services contexts (and Sun has proposed an ASN.1
approach tailored to just that situation, see
http://developer.java.sun.com/developer/technicalArticles/WebServices/
fastWS/ ) but that's a fairly specialized scenario.
