Re: ASN.1 and XML

[Al Snell <alaric@alaric-snell.com>]

On Fri, 25 May 2001, Rick Jelliffe wrote:

> Does being pro-XML thereby make one anti-ASN.1?

Not necessarily, but XML is perhaps cursed by having evangelists who
become closed-minded and reject other technologies forthwith - a curse
that usuall arises form hype...

> If XML can be used to encode ASN.1 documents, and if ASN.1 can be used for
> schemas for XML, then the issue is not that one is better, but whether XML
> _should_ well be used as a standard encoding for ASN.1 or that ASN.1 should
> be the "schema" system for XML.

Or even "a" schema system for XML, there's nothing wrong with choice. The
PSVI is almost entirely a subset of the ASN.1 equivelant; the only thing
ASN.1 lacked was regular expression constraints on strings, so they were
added. That structural isomorphism means that, at the abstract hearts, XML
and ASN.1 are more or less the same (which is faintly irritating if you
consider the work going into XML when there's something that's
fundamentally the same already out there :-). Formally expressing a
mapping from the ASN.1 "infoset" to XML, the XML Encoding Rules, as well
as formal rules to convert XML Schemas into the equivalent in ASN.1 will
seal the union, and (without anyone having to worry about anything) XML
will suddenly be a small part of ASN.1 in all but name...

Which won't stop people from using XML without bringing in other parts of
ASN.1 like PER or the ASN.1 type notation, but those paths will be there
to reach into places where XML cannot tread, and due to the isomorphisms,
the conversions will be automated.

> based on what they consider their most productive next step to be.  If there
> are no tools, no-one will pick ASN.1.

Indeed. This needs fixing. We're working on it...

> In the long term, one would hope that the technical superiority of a
> technology attracts the masses to it.

Heh! That hasn't worked yet. Marketing forces rule the day.

> If ASN.1 (or its ilk) are better,
> ASN.1 fans need to figure out how to get from here to there: piggybacking on
> XML is surely the only game in town. To say "Pick ASN.1 _instead_ of XML" is
> to fail to learn King Canute's lesson.

http://asn1.elibel.tm.fr/xml/ :-)

> Rick Jelliffe

ABS

-- 
                               Alaric B. Snell
 http://www.alaric-snell.com/  http://RFC.net/  http://www.warhead.org.uk/
   Any sufficiently advanced technology can be emulated in software