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Re: Boeing XRI Use Cases

From: Julian Reschke <julian.reschke@gmx.de>
Date: Tue, 15 Jul 2008 17:39:00 +0200
Message-ID: <487CC494.2070305@gmx.de>
To: John Bradley <john.bradley@wingaa.com>
CC: Mark Baker <distobj@acm.org>, "Booth, David (HP Software - Boston)" <dbooth@hp.com>, "www-tag@w3.org" <www-tag@w3.org>

John Bradley wrote:
> ...
> It is my belief that there is no place in the spec where xri: is used as 
> a XML namespace name that a URL could not have been used.
> 
> <XRD version="2.0" xmlns="xri://$xrd*($v*2.0)">
> 
> This uses the XRI versioning syntax that we have some attachment to.
> 
> David Orchard has concerns that this is not a valid URI.
> ...

Well, it isn't, until you register "xri" as a URI scheme. I think this 
is why many people are concerned by this: that "xri" identifiers leak 
out into places that do only allow U^HIRIs.

> That is one question I don't think has been resolved completely.
> If the scheme were registered is this valid as a URI without further 
> escaping?

Potentially.

Why does it start with "//" when it doesn't use an authority (see 
RFC3986, Section 3)?

> ...
> My question around WEBDAV was not really directed at XML but rather the 
> processing by WEBDAV aware clients of webdav URLs in the http: scheme?
> 
> WEBDAV extended the operators beyond GET and POST, and had a extended 
> web server that dealt with information encoded in the path.

No, in WebDAV there is no information encoded into the path. It only 
uses additional methods, the HTTP URLs are the same as always.

> We have not proposed new operators to extend the http protocol with HXRI.
> 
> If xri and webdav and http are to all share the same http: scheme 
> addressing then how are the clients like XDI servers and possibly web 
> browsers going to recognize these URIs?

Are you asking for feature discovery? WebDAV does that through OPTIONS 
(see <http://greenbytes.de/tech/webdav/rfc4918.html#rfc.section.10.1>).

> Is there something we can learn from others attempts to fit themselves 
> into the http: scheme?
> 
> Some people feel that if we conform to http: scheme addressing we must 
> still justify XRI in some way.
> 
> How have other people met this challenge?
> 
> I ask about WEBDAV because it would appear to have some of the same 
> issues we will encounter tying to re-use the http: scheme.
> 
> I will have a look at RFC 2518 to see if it can shine some light on this.
> ...

I don't think WebDAV shares these issues, as it just adds new methods to 
  manipulate otherwise standard HTTP resources. That being said, you 
want to look at RFC 4918, not RFC 2518.

BR, Julian
Received on Tuesday, 15 July 2008 15:55:00 GMT

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