Internet Info 1997 December/Internet_Info_CD-ROM_Walnut_Creek_December_1997.iso/ietf/92jul/udi-minutes-92jul.txt

Text File | 1993-02-17 | 10KB | 270 lines

Editor's Note:  Minutes received 7/14

CURRENT_MEETING_REPORT_


Reported by Tim Berners-Lee/CERN

Minutes of the Universal Document Identifiers BOF (UDI)

The UDI BOF was held at the 24th IETF in Cambridge, MA, USA on July 14,
1992.

Introduction

Tim Berners-Lee opened the BOF with a summary of the terms used in the
discussion to date.  The information one quoted in a reference to an
object could comprise many things, among which were possible one unique
name, (Unique Resource Number, URN was one acronym), and zero or more
addresses (Uniform Resource Locators or URLs) which gave instructions
for retrieving the object.

The purpose of the meeting was to formalize a standard string syntax for
URNs and URLs in general, and to define specific syntaxes for addresses
in the namespaces of each of the existing network protocols.  [There was
a discussion on acronyms at various times.  URL was decided upon for an
address, and that is used throughout these minutes for clarity.]  The
result should be a standards track document (requiring a working group,
which should probably be in the Directory Area but could be in
Applications).

NOT to be discussed were the differences between names and addresses,
URN schemes (which are not yet well enough defined), the full set of
information to be given in a reference, or IPv7.

To be discussed were the overall string syntax, including allowed
characters and escaping systems for unallowed characters, the order of
components (little/big-endian), punctuation characters, as well as the
particular prefix to be used to identify each namespace.

Specific schemes should be handled in appendices of the resulting
document, and should include:



Prospero     FTP      WWW       telnet    net man. db?
nntp         WAIS     gopher    finger    X.500



Discussion

We need methods of keeping up to date the set of appendices without the
same standards track procedure which applies to the full document.

It was pointed out that for WAIS one could imagine a separate name space
for databases and for documents.  If this was taken further, a separate

                                   1





prefix would be used for each type of object.  It was on balance agreed
that this could go too far.  One prefix should be used per protocol, but
it should be made clear how to determine the type of an object from the
URL.

Peter Deutsch is concerned that we need a syntax for attaching a URN to
a URL, but accepted that it was not for discussion at the BOF.

Cliff Lynch suggests three part structure of name, address, and other
stuff.  Peter Deutsch suggests that the document should talk about what
the addresses aren't, in a section on Scope.  This section could also
provide an example of a complete reference, including other information,
by way of explanation but not recommendation.

Tim Berners-Lee had submitted in the background document, the W3
implementation:

scheme: ____blah___

(the syntax of ____blah___ depending on the value of scheme, within
certain constraints.)  There was no dissent, although he noted that this
is the reverse order from the WAIS proposal.

John Curran has concerns about URLs being resolvable in such a way that
any two references to the same URL get the same thing.  (unambiguity).
It was generally felt that the system W3 uses to allow URLs to be
incompletely quoted in context was an application issue and was not
relevant.

The issue of what we are identifying came up ``resource locator''?  -- a
scheme for somehow identifying resources.  Perhaps identifying procedure
for locating a resource (Karen Sollins and Cliff Lynch).  Cliff Neumann
suggested Document Access Instructions as an alternative
handle/name/identifier for these addresses.  URL was decided on by an
almost unanimous vote.  (Uniform Resource Locator).

Peter Deutsch pointed out that we want to focus on interoperability, not
on longevity.  We ought to be able to hand URLs around in short-term,
but not long-lived.  URLs are not unique (in the sense that one document
may have several).  This should be made clear in the document.

The class of object you get back should be predictable (Cliff Lynch).
W3 has a real problem with that, since everything is a ``document'' and
handled in a similar way.  Might get a pointer to a database in a piece
of mail.  The question of whether one gets back a file or a directory
from a FTP URL arose.  Archie really wants to know what it is getting
back.  Within a scheme, should be documented syntax that will clarify
which sort of object will come back.  If we go too far down this track,
we fairly quickly get to full object-oriented world, with fullscale
typing.  Alan Emtage.  suggested that simple enumeration of acceptable
types.  Extensions based on documented new subtypes, based on documented
protocols.

A separate issue of whether human or only machine readable.  Previously,

                                   2





included issue of printable.  This is needed because don't have names
now.  Question arose of whether once these addresses exist will be
replaceable with names - will be presented as new functionality, not
replacing existing systems.  Agreement on some way of specifying class
of objects.

``Context'' Prefix

IT WAS AGREED that the context, or namespace prefix be the first
(leftmost) part of the URL, and be separated from the rest of the URL by
a colon.

The punctuation ``//'' was discussed.  Currently, W3 URLs use ``@'' for
login information.  An extension of server the server hostname can
include a port number in all current schemes.

The issue of how to manage additional schemas was discussed.  Each
appendix should be checked out by a particular group within the IESG,
and perhaps should be an ``Expermental Standard,'' rather than simply an
``informational RFC.'' The document will describe how to write
appendices.

Syntax Details

The syntax should be human typable (majority agreement).

Should one use punctuation, or attribute-value pairs?  Attribute value
pairs get mispelt.  (note x.400 vs.  Internet addresses)

It was decided to use a short string with punctuation rather than an
attribute-value pair system.

We must specify the terminator (by declaring some characters as illegal
inside a URL).

Is a URL nestable?  If one URL can contain another, one needs nestable
begin-end pairs.  (Alan Emtage).  Currently W3 URLs are not nested
visibly although escaping allows URLs to be encapsulated within URLs,
for example by gateways.

Allowed characters:  characters should be disallowed if they are needed
as terminators (`''', `;') or are too easily mutialtable by passage
though (for example ASCII/EBCDIC/ASCII) gateways (tilde, backslash).  A
subset of an ISO 7-bit code should be defined, with reference to MIME
work.

Future Discussion

Mailing lists:  NIR list at McGill will be used by Jill Foster and
George Brett's NIR BOF. [e-mail] will be used by this Group.
First of all, we should ask Mike Schwartz whether he is willing to run
all mailing lists on one machine (at least nir and url) in order to cut

                                   3





down on multiple copies opf cross-posted messages.

Accomplishments

Things which the meeting had brought to light included:


   o ``File:''  is too broad a description, ``ftp:''  would be better.
     If a given client knows that it can in fact access some FTP sites
     as local files, that is a local client issue.

   o Escaping is to be defined.

   o Relative naming is a client issue.

   o We should look at what we call ``news:''  (``usenet:''?).

   o We should we be able to tell what sort of an object we have (eg
     database or document) by simple examination of the URL

   o We need a scheme for managing the addition of new schemas (cf
     Directory object definitions).

   o The document should be an ``Experimental Standard'' RFC.

   o Mailing lists will be defined and a single message sent to cniarch
     to say what is happening.

   o The time-frame for the document was:  soon.  Probably in the OSI
     Directory Services Area (Erik Huizer has suggested this).  We need
     a working group if we want to go through the IESG. But in reality,
     if have big applications buying in, then will be a de facto
     standard.


Final Comments

We may need to separate WAIS from Z39.50.  (C Lynch).  We may also need
SQL. Also we should include X-junk:  type extension mechanism for
experimental schemes.

These minutes noted on-line by Karen Sollins (Thanks!)  and edited by
Tim Berners-Lee.  They are available as:
URL http://info.cern.ch/timbl/Public/USTrip1992/IETF-24/UDI]_BOF_
Minutes.html

Attendees

Vikas Aggarwal           [e-mail]
Harald Alvestrand        [e-mail]

                                   4





Mark Baushke             [e-mail]
Tim Berners-Lee          [e-mail]
George Brett             [e-mail]
Mitchell Charity         [e-mail]
Jodi-Ann Chu             [e-mail]
John Curran              [e-mail]
Richard desJardins       [e-mail]
Peter Deutsch            [e-mail]
Alan Emtage              [e-mail]
Jill Foster              [e-mail]
Ray Freiwirth            [e-mail]
Jim Fullton              [e-mail]
Martyne Hallgren         [e-mail]
Erik Huizer              [e-mail]
Bill Manning             [e-mail]
Clifford Neuman          [e-mail]
Sam Nicholson            [e-mail]
Jon Rochlis              [e-mail]
Karen Roubicek           [e-mail]
Richard Schmalgemeier    [e-mail]
Vincent Sgro             [e-mail]
Jane Smith               [e-mail]
Karen Sollins            [e-mail]
Simon Spero              [e-mail]
Chris Weider             [e-mail]



                                   5