Re: misconceptions about MIME [long]

Ned Freed <NED@sigurd.innosoft.com>
Date: 29 Oct 1992 09:53:10 -0700 (PDT)
From: Ned Freed <NED@sigurd.innosoft.com>
Subject: Re: misconceptions about MIME [long]
To: masinter@parc.xerox.com
Cc: nsb@thumper.bellcore.com, wais-talk@quake.think.com,
        connolly@pixel.convex.com, www-talk@nxoc01.cern.ch,
        ned@sigurd.innosoft.com
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> The arguments that in-band designation of document format is better
> than out-of-band information may apply in the electronic mail
> scenarios, where there is a single sender, multiple recipients, and
> the recipient has no control over what the sender might send.

The argument is identical for most file servers, which have even less control
over the specifics of what files they offer for retrieval. File servers usually
rely on contributed material and only rarely have anything resembling precise
control over the material they offer.

> Instead, imagine, if you would, another scenario, of a WAIS or Web or
> anonymous FTP archive, which wishes to make available the latest
> version of the MIME specification. Let us suppose, in addition, that
> the publishing service has three different representations of the
> document, one marked "MIME rich-text", one marked "postscript", and
> one NetFax.  Furthermore, let us suppose (as has been proposed) that
> the document types are marked by their MIME Content-type header
> designation.

Nothing wrong with this.

> If I wish to retrieve the document, say to view it, I might want to
> choose the available representation that is most appropriate for my
> purpose. Imagine my dismay to retrieve a 50 megabyte postscript file
> from an anonymous FTP archive, only to discover that it is in the
> newly announced Postscript level 4 format, or to try to edit it only
> to discover that it is in the (upwardly compatible but not parsable by
> my client) version 44 of Rich Text. In each case, the appropriateness
> of alternate sources and representations of a document would depend on
> information that is currently only available in-band.

Even if this happens (I have strong doubts that it will since documents made
available for public retrieval tend to converge rapidly to lowest-common
denominator usage) you have failed to propose an alternative that solves this
usefully.

> I believe that MIME was developed in the context of electronic mail,
> but that the usage patterns in space and time of archives, database
> services and the like require more careful attention (a) to
> out-of-band information about format versions, so that you might know,
> before you retrieve a representation, whether you have the capability
> of coping with it, and (b) some restriction on those formats which
> might otherwise be uncontrollable.

And I disagree. You still have failed to explain how to overcome any of my
objections to this approach.

> Finally, as much as I've tried to resist, I'll characterize your
> description of my response as 'repeated failure on your part to read
> the words I was writing' as 'inflammatory hogwash'.

Well, you're doing it again. You have failed to explain you intend to overcome
any of the obstacles I've pointed out, precisely as if you have not bothered to
read any of my previous response. Since one of them is the halting problem in
disguise your method of overcoming it (assuming you have one) will be the
computing news of the century.

I have no intention of answering any further mail from you until you come
to grips with the objections I have laid out for about the tenth time.

Finally, let me point out that I speak as one of the maintainers of one of the
largest archive of TeX material available anywhere. This material has been
available via MIME-compliant mail server (and of course FTP) for over six
months now. This archive contains hundreds of PostScript documents as well
as all sorts of other stuff. The problems you seem to think are endemic to
this sort of services have yet to materialize.

				Ned