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   Re: Proposal for src files

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  • From: Peter Murray-Rust <peter@ursus.demon.co.uk>
  • To: "W. Eliot Kimber" <eliot@isogen.com>,xml-dev@ic.ac.uk
  • Date: Thu, 02 Apr 1998 08:51:19

At 11:22 01/04/98 -0600, W. Eliot Kimber wrote:

>But maybe I'm just a crank.

No. But you have a level of vision and understanding that makes it
difficult for others like me to follow. This is a recurring theme in the
whole of current  IT/CS - there are 'right' solutions that people simply
are not able to comprehend or find too difficult to adopt.  In those cases
one ends up with a small number of people who provide a solution (often at
high cost) to a large number of people who don't understand an don't own
it. IMO the single most important thing about XML is that it makes things
accessible to at least a hundred times more people than other technologies.
We are seeing this debate frequently now - 'what does XML do that XYZ
doesn't?' My answer is that it can relate to ordinary hackers - and
possibly even to inspired management.

>At 09:22 AM 4/1/98, Peter Murray-Rust wrote:
>>Is it possible to combine these two so that we express a DTD in a standard
>>XML notation? Many of us do this already, but I suspect that our tagset and
>>syntax vary. If we could agree on this - and I don't see this as
>>technically difficult - we could help both communities. 
>It is not technically difficult--it is, however, practically impossible
>except in the most trivial way (a direct transliteration of DTD syntax)

I was thinking of something very trivial (you didn't expect anything else
from me, surely :-) - a lossless translation of DTD to XML format (and vice
versa) without any inheritance, mapping, etc. I thought this was
uncontroversial - but maybe I haven't got my point over.

>unless it is *explicitly* defined as a base architecture with very clear
>rules for specialization. And even then, developing that architecture will
>be difficult at best.
>The reason it's practically impossible is because getting agreement among a
>community of interest as wide and varried as the XML community on a subject
>of such importance as how to represent the definitions of document types is
>one of the hardest types of things there is to do. There are simply too

I wasn't trying to tackle this. We already *have* a definition of document
types - it's XML 1.0. I was simply suggesting we standardised an XML-based
syntactic representation of this.

>many different ways to do it, too many different ways to represent things,
>too many interested parties. The degree of expressibility of schemas is
>open ended, meaning that any design, to be useful, must be maximally
>extensible. Defining extensible languages is hard.
>I personally think that trying to define a common markup approach to DTD
>representation is a waste of time: the answer is either obvious (Wayne
>Wohler did it over 5 years ago) or impossible to achieve consensus on. The

If it's obvious and already done, perhaps it should be re-used?

>first is not useful compared to the cost of defining and maintaining it,
>the second cannot be achieved by any sort of consensus-based approach. So
>there's no point in bothering. 
>The minimum abstractions needed to define element types are already defined
>by the SGML property set--if your schema language can get you to these
>abstractions, fine.  

Perhaps all we need is a representation of the property set in XML format.
Would *that* be controversial?

>I say let groups define their own schema approaches without bothering to
>find too wide of a consensus. If one particular approach gains widespread
>acceptance, then fine. If it doesn't, we're no worse off than we were
>before, *but* we haven't wasted a huge amount of a scarse resource on a
>doomed effort.  This provides opportunities for vendors to distinguish

Although I value your judgement, I don't see why this is 'doomed'. The same
could have been said about SAX. I'm proposing that we take simple steps to
see if there is a communality here that we can use.

I am not enthralled by suggested that we let anyone do whatever they like.
We can then guarantee that whenever we encounter a foreign schema it will
be another significant task to understand and code it. This would - as I
suggested - simple move the 'battleground' from tags to schemas. We have
avoided having parser wars with SAX and DOM - couldn't we at least look at

I agree resource is scarce. I think SAX showed an excellent way of
conserving such resource. If we followed the same process we might find out
at an early stage whether we were doomed or not :-)

>themselves by providing different types of validation and constraint
>support. As long as they always support normal DTD syntax, I see that as a
>good thing--if someone like Microsoft produces a product that helps me
>create better data repositories, then I'm happy to buy and use it, as long
>it accepts and generates normal DTDs with the level of fidelity I require.
>But why should I give Microsoft (or anyone else) free engineering support
>by being involved in a schema development effort? It doesn't make sense to

We gave them (and lots of others) free engineering support for SAX. I put a
lot of effort into that and I'm not complaining :-) Actually even just for
me, the effort was less than writing APIs for every parser. Multiply that
by 10000...

>me. If they want my help, they can pay me.  I already have what I want and
>need and I'm capable of providing for myself if I need more (as is anyone
>with a copy of Lark and a Java book).

I'm afraid I (and I think many others) aren't :-) and that is why I raised
the problem. Being a part-time academic who does XML in their spare time I
don't have the resources of a commercial company - and I suspect there are
many others in a 'similar' position. They will come across 'schemas', 'src'
files, etc. and need to know what to do with them. I hope we have a more
constructive message than simply "wait and see what the large commercial
organisations do, and then buy their products" :-).  The WWW grew in large
part through the efforts of large numbers of large number of people who
picked up a common philosophy and developed it. If the message now is that
"unless you are a member of W3C you shouldn't be involved in XML
development" it represents the passing of an era, and I'll need to rethink.


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