SGML: What's so big about XML?
Subject: Re: What's so big about XML?
Date: Tue, 28 Jan 1997 14:43:21 -0600
From: Len Bullard <cbullard@hiwaay.net>
Newsgroup: comp.text.sgml
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kendall shaw wrote:
>
> Hi,
>
> I've been reading about XML a little, and I understand it's syntax
> pretty much. What I don't know about is how it will be used. What
> about XML would be easier to present over the web than SGML? Or,
> what about presenting SGML on the web is so hard that we would need
> XML? How will presentation of XML element structure be done >(stylesheets)?
An overview, not authoritative, but not uninformed:
SGML has many features that require a parser to be quite complex.
Some of these features support requirements that either don't
apply to hypermedia, or don't occur often enough to concern
all applications. SGML CAN be used on the web and is everyday
in the form of an SGML application called HTML. To understand a
difference, consider how many times we have seen the phrase
"... HTML, a subset of SGML" and had to remind the writer
that HTML is NOT a subset of SGML, it is an application.
However, XML IS a proper subset of SGML. It is designed such
that a parser can be *easily* written for any application that
wishes to use its syntax. Furthermore, as we speak, a
subset of other hypermedia link and location
specifications (ie., HyTime and TEI) is being written
so that hyperlinking among XML applications will be
portable and interoperable.
That alone is worth the price of admission.
But there's more!
In the next phase, the stylesheet/processing specification
component will be written such that XML applications
can exchange information with assurance of rendering
and behavior fidelity. This is a fantastic contribution
to a community that has needed this for a decade now.
In short, XML will provide an integrated suite of
specifications which an application developer
can in part, or in total, use to create applications
for the Internet and World Wide Web which are compatible
with current systems, and which take advantage of the
power of generalized markup.
Note carefully: XML does not replace SGML or HTML.
In the former, XML is a subset so brings, as originally
intended, SGML to the Web. In the latter, XML applications
will work with and augment HTML applications by making
it possible to use languages such as the Chemical Markup Language (CML)
as effectively as one now uses HTML. Browsers and plugins
can be written for very specific information domains that
still interoperate in the generalized environment of the
WWW and Internet.
One market for this will be moving the gigabytes of SGML
out there, originally designed for print applications or
say, military technical manuals onto the Internet and
into intranets.
The XML Working Group is *furiously* moving on its
tasks. I expect by spring to see some prototypes
emerging from the members. I expect by fall
to see real applications. Just a prediction.
Len Bullard
Lockheed Martin
Subject: Re: What's so big about XML?
Date: Wed, 29 Jan 1997 14:16:20 -0600
From: Len Bullard <cbullard@hiwaay.net>
Newsgroup: comp.text.sgml
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Paul Hayslett wrote:
>
> Hmmmm..... I would have said something along the lines of:
[snip]
> "The best part is that we now get to watch as vendors who, until recently,
> were charging 10's of 1000's of dollars per license for SGML-aware products
> try to educate us on the need for moderately priced systems which handle
> only the subset of SGML that users are likely to use. As if we hadn't been
> asking for exactly that for 10 years."
>
> But maybe I'm just a cynic.
I can't quarrel with your assessment. That is why IADS is out there for
free.
People took significant risks to make that possible, and paid a price.
I am one of them.
But, water under the bridge. The significance of XML is that the
vendors, academicians, SGML designers, hypertext experts and yes,
some significant players from the HTML community have sat down
under the aegis of the W3C to create XML. That's amazing.
Now, what would be most interesting would be a discussion of the
kind of products that can be created with XML. Using a similar
design, we built IADS and gave it away. Neat little browser, a
bit long in the tooth now, but it proved a lot about the use
of simplification of SGML and the use of an automated stylesheet
system. That's one model. Another and probably more interesting
model is Peter Murray-Rust's CML language and application. A lot
can be done with a GUI tree object.
Wouldn't it be a good thread to talk about applying XML and what an
XML product would look like, feel like, and do? How simple can
we make an XML application? How easy can we make it to use?
What do you want it to do and how do you want to do that?
The SGML community has been scarred for years with relentless
infighting and scorn. The marvel of XML is that it IS happening
and who is there doing it. As a decade long denizen, I am
not just a little thrilled that this is happening regardless
of cause or circumstance. It is important, I think, to now
ask ourselves what we shall do with this toy. What will it
be like to have something a bit more powerful than HTML,
a little bit harder to use, but with a lot more possibilities for
domain-specific data handlers that interoperate and can
share linking and stylesheet definitions?
A real opportunity is opening up for the first time in a decade.
What shall we make of it?
Len Bullard
Lockheed Martin