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Subject: RE: [xri] Fwd: for names consisting of an adiminstrative hierarchy and a path, HTTP/DNS is as good as it gets
---------- Forwarded Message
----------
Subject: for names consisting of an adiminstrative hierarchy
and a path,
HTTP/DNS is as good as it gets
Date: Tuesday 19 April
2005 07:34 pm
From: Dan Connolly <connolly@w3.org>
To:
www-tag@w3.org
On 15-March-2005, the OASIS XRI TC released some documents
for
public review...
http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=xri
...
and the TAG started looking at them on 22 March...
http://www.w3.org/2005/03/22-tagmem-minutes.html
Not
having read the XRI docs (because of patent concerns), today I
suggested the
following line of argument:
1. XRIs follow the pattern of an
administrative hierarchy
followed by a path
2.
http/DNS handles the case of an administrative hierarchy
followed by a path, and is ubiquitously deployed
3. A specification
SHOULD reuse an existing URI scheme
(rather than create a new
one) when it provides the
desired properties of identifiers and
their relation
to resources.
-- http://www.w3.org/TR/webarch/#pr-reuse-uri-schemes
therefore
4.
The XRI work should use http/DNS; the xri: scheme
should
not be introduced.
Point 2 seems to merit elaboration. So I'm taking a
look
at the docs now...
In [XRI] section 3. How XRIs Help Solve These
Problems, subsection
3.1 Persistent Identification, we see the familiar
story
of a link breaking because a department gets renamed.
http://department.agency.example.org/docs/govdoc.pdf
moves
to
http://newdept.agency.example.org/docs/govdoc.pdf
Then,
it says, "A much better solution would be to assign the
resource “govdoc.pdf”
an identifier that never needs to change or
be reassigned." Quite!
Absolutely! Cool URIs don't change[TBL].
[XRI] continues... "This can be
accomplished using a fully
persistent XRI such as the following:
xri://@!9990!A58F!1C3D/!2495 "
Well, now if the govdoc publisher had the
foresight to
consider the possibility that the govdoc resource
might
outlive the agency or its name, they could have used
a nice sturdy
http/DNS URI in the first place, ala
http://govlib.example/2005/govdoc
That's
assuming the government prefers to take responsibility
for long-term
publishing of documents itself. Of course, this
could be outsourced to
xri.com , who might issue the name...
http://9990.xri.com/2005/A58F!1C3D/!2495
and
then resolution can happen by way of HTTP (or https) redirects,
analagous to
the way XRI resolution is described.
The point is
* yes, it's
useful to assign a persistent name in the
first place, in
case a resource outlives its original
publisher,
but
* there's no reason not to use http/DNS to do
this
When I started to read the next section, 3.2 Federated
Identification,
I thought maybe XRIs had made the split-point between the
administrative
hierarchy and the path invisible at the syntax level, ala
the
long-discussed path: scheme[DLL]. But it says,
"Once we have reached
the public XRI authority
@example.org*agency*department, it can switch to
internal delegation"
which is nothing tricky at all; it's just like
the
apache InternaRedirect mechanism (and analagous mechanisms in
other
HTTP server architectures).
[XRI]
http://www.oasis-open.org/apps/group_public/download.php/11857/xri-intro-V2.0
-wd-04.pdf
... which bears the "Location"
http://docs.oasis-open.org/xri/xri/V2.0
which,
by supreme irony, is 404
[TBL] http://www.w3.org/Provider/Style/URI
[DLL]
The
Path URN Specification
Daniel LaLiberte (liberte@ncsa.uiuc.edu)
Fri, 17
Mar 1995 16:58:25 -0600
http://lists.w3.org/Archives/Public/uri/1995Mar/0027.html
--
Dan
Connolly, W3C http://www.w3.org/People/Connolly/
D3C2
887B 0F92 6005 C541 0875 0F91 96DE 6E52
C29E
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