# Re: New URM paper with additions!

Mitra (mitra@path.net)
Wed, 20 Oct 1993 22:14:31 GMT

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    From: mitra@path.net (Mitra)

    Subject: Re: New URM paper with additions!

    Message-Id: <CF7v48.1EJ@pandora.sf.ca.us>

    Date: Wed, 20 Oct 1993 22:14:31 GMT

Michael Mealling (ccoprmm@oit.gatech.edu) wrote:
: This is a new version of the paper I submitted in Amsterdam. I will be
: in Houston this time to defend it.
Thanks Michael, I'm glad you'll be able to hear the feedback
this time :-)

Overall I think this paper covers the important issues around
moving URN's URLs and Meta information around in globs togother.
As we've seen in the URL discussion whenever the concept of removing
types comes up, if we've removed meta-information from URLs then
we immediately need some other way to pass it around.

However I think the format proposed sucks. To be honest I thought
my printer had screwed up the formatting. I'm sure we can come
up with better ways of presenting human-readable information.

: insert your favorite TLA where needed.)

Do you see your URT as being equivalent to what John Kunze and others
are calling a URC? Or do you see URCs as a special case of a URT

: 2.2.2 The Format_Scheme
: <ellipsed>
: The second uses the value "MIME" as a specifier which denotes
: that the value within the double quotes is a MIME encoded set of
: meta-information. This allows for other character formats to be encoded 7-bit
: clean to allow for easy transmission. The actual format of the data within the
: MIME package should only be one of the allowed Formats from the initial portion
: of the Format_Scheme.

Maybe an example is needed, but I'm unclear what a MIME encoded set
of meta-information is. Do you mean that the rest of the information
is base-64 or whatever coded, or that the information looks like
a mime header or what? A full example would be good.

Also ... I think the Format scheme needs to be just another data item
that can occur at any point in the URM. We will definately have
the case where a documents title is in one character set. Buts its
publisher or author's name, is from another. If we define a
default then we can remove this in most cases.

: 2.2.3 The list of encoded items
: White space of any type is allowed here.
Allowed, or significant?

: If quotation marks are
: needed within these items, then they should be quoted with a '\' in the C
: style of special character quoting.

Same comment as on Chris's paper, lets stick to one scheme of
escaping illegal characters for URL, URN and URM. Since we've
adopted %xx for URLs I think we should support that here.

: URM:IAFA:en_US.iso88591::"Author: John Doe"::"
: Title: \"My Book\"
: "::"
: Format: PostScript
: ":::

As I said above, I think this is truly horrible, and even worse in
the example under URT. If you want these all one one line, then
I'd suggest something more like:

URM::Tag: Value::Tag: Value::Tag: Value:::

Tag is same as you ahve it. Value eitehr doesnt need quoting at all
(quotes are redundant if : is escaped) or only needs quoting if
it contains a :.

I'd suggest that a formalised scheme for representing this on
multiple lines be adopted. Specifically, remove the :: and replace
with new-lines. Adopt the same rules as for RFC822, that if
the line begins with white-space then its a contination, otherwise
its a new tag.

Your examples then become either.

URM:IAFA:en_US.iso88591::Author: John Doe::Title: "My Book":::

or

URM:IAFA:en_US.iso88591
Author: John Doe
Title: "My Book"
Format: application/postscript

(note I changed Format to the IETF type, better not to propogate
incorrect types)

: 3: The Uniform Resource Template (URT)

I think this section is really good, I especially think the peice
about precedence is excellent, and handles neatly the problem of
how to match meta-information with either the URN or a specific URL.

: 3.5 Example URTs

Again, the formatting is horrible. I'd suggest the following , using
the same examples.

URN:IANA:626::Dir:6345:::
URL:gopher://gopher.gatech.edu:2048/11/Computing.Resources
URM:IAFA:en_US.iso88591
Author: Michael Mealling
Subject: OIT Computing Resources
URL:http://www.gatech.edu/Computing.Resources
URM:IAFA:en_US.iso88591
Author: Michael Mealling
Subject: OIT Computing Resources (OIT Home Page)
Size: 16k

Note also, that the URM: line is redundant in this layout, and
if the encoding was the default could be removed.

To show how this might simplify. Since the Meta information can
be placed on the URN as well this would become.

URN:IANA:626::Dir:6345:::
Author: Michael Mealling
URL:gopher://gopher.gatech.edu:2048/11/Computing.Resources
Subject: OIT Computing Resources
URL:http://www.gatech.edu/Computing.Resources
Subject: OIT Computing Resources (OIT Home Page)
Size: 16k
I really like the idea of having a scheme which scales well, i.e.
simple cases look simple, but complex cases can be handled with
a complexity of representation proportional to the complexity of
the case being handled.

- Mitra

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