# Fragments are Client side [Was: URN Requirements ]

Daniel W. Connolly (connolly@hal.com)
Mon, 16 May 1994 23:25:17 -0500

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    Message-Id: <9405170425.AA03361@ulua.hal.com>

    To: avatar@notebook.aus.xanadu.com (Andrew Pam)

    Subject: Fragments are Client side [Was: URN Requirements ]

    In-Reply-To: Your message of "Tue, 17 May 1994 11:59:00 EST."

                 <9405170006.AA0034@notebook.aus.xanadu.com>

    Date: Mon, 16 May 1994 23:25:17 -0500

    From: "Daniel W. Connolly" <connolly@hal.com>

In message <9405170006.AA0034@notebook.aus.xanadu.com>, Andrew Pam writes:
>
>> My understanding of Xanadu is that it makes extensive use of quoting of
>> portions of documents ( a weakness, IMHO of the WWW) this needs handling
>> by specifying a URN (or URL) and a fragment, standardisation of fragments wa
>s
>> bumped off the agenda of the URI group at the DC IETF, and I still think we
>> will need to tackle it sometime.
>
>Well, in Xanadu any (possibly discontiguous) span of bytes is a valid endset
>for a link, so effectively Xanadu URLs would have to contain a "fragment list"
>,
>if you will.

The #fragment part of a WWW address is for use by the client after
it has retrieved the info described by the rest of the address.

Hence I expect that these Xanadu spans are more like WWW search
specifications, in that they select certain information to bring
over the wire.

Somewhere in the WWW doc, it explains that a WWW "document" is
defined as the smallest unit of information that can be retrieved.

So if a server is willing to give out, for example, certain paragraphs
of a given document, it would be incorrect to write:

HREF="xanadu://host/dir/file#para1-5"

Rather, you would write:

HREF="xanadu://host/dir/file?para1-5"

or perhaps just:

HREF="xanadu://host/dir/file/para1-5"

if the server doesn't need the ? to disambiguate. Acutally, in practice,
you'd probably end up writing something like:

HREF="xanadu://host/lk23j45l2k34j2li34j2l3i4j234345lkj"

where ..lkj423.. is a base64 encoding of some packed representation
of a xanadu address.

Dan

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