W3C home > Mailing lists > Public > w3c-sgml-wg@w3.org > October 1996

Re: B.1 and B.2 results

From: <lee@sq.com>
Date: Tue, 22 Oct 96 12:14:37 EDT
Message-Id: <9610221614.AA27963@sqrex.sq.com>
To: dgd@cs.bu.edu, w3c-sgml-wg@w3.org
> I can agree with Gavin that catalogs are more elegant, but in some contexts
> they may not be more convenient. And as Tim and Michael note, a header that
> is integral is less likely to be lost...
> PS does anyone else have an opinion on this?

Of course :-)

Yes, I think the header should be inside the document, not in a separate file,
since for internet work, the CATALOG file might not even be accessible.
We had to deal with this for Panorama -- consider the case where the
SGML is the result of a database query you just paid $.5 for.  You don't
really want Panorama probing around in the database trying to find a
file called CATALOG or catalog (it searches for both -- our nod towards
the unfortunate wording of the TR which says the name of the file must be
case insensitive).  Each probe might cost money, and in any case the
resulting error messages aren't always distinguishable from text.

Panorama understands some processing instructions to find the DTD, style
sheet, etc. and to suppress searching for the catalog.  Recently, we
even added another processing instruction to let Panorama know a URL for
the document it's viewing, to work around deficiencies in Unix Netscape.

Allowing a MIME-style header in XML will make all that much simpler.
Requiring a MIME-style header in XML files will allow them to be
identified reliably, rather like a DOCTYPE line in SGML.  The header
could also specify the XML version, for which we will be very grateful
when we are working on XML 2.0.  I still have email messages from 1983
and earlier; they are still valid.  Where the meaning of headers has been
changed, it has only done so in the presence of a Mime-version header.
There is no "implied MIME header" :-) -- if a mail message has no
Mime-version, it is not MIME-compliant, and must be treated as per
RFC 822.  In the same way, XML-Version could be required, and, if not
present, the file is either taken to be XML 1.0 or plain text, at pleasure.

This sort of use of headers allows forwards compatibility and a great
deal of interoperability with existing systems.  It will also be a lot
easier to get acceptance in the IETF world if XML integrates with and
builds on existing IETF international standards such as MIME.  The ISO
is not the only international standards body in the world :-)

Received on Tuesday, 22 October 1996 12:14:51 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 20:25:04 UTC