W3C home > Mailing lists > Public > xml-dist-app@w3.org > December 2001

RE: Possible new issue on interpretation of relative URI actors

From: Henrik Frystyk Nielsen <henrikn@microsoft.com>
Date: Tue, 4 Dec 2001 09:11:34 -0800
Message-ID: <79107D208BA38C45A4E45F62673A434D05A83ECA@red-msg-07.redmond.corp.microsoft.com>
To: <noah_mendelsohn@us.ibm.com>
Cc: <Noah_Mendelsohn@lotus.com>, <xml-dist-app@w3.org>

In SOAP, all we use URIs for is as identifiers. A role is identified by
a URI which by definition identifies a resource. We say nothing about
what the semantics or properties of that resource and I think this is
very important that we don't do.

When you pick a specific URI scheme (like for example HTTP), you
explicitly pick a URI space with certain naming properties: whether it
is hierarchical, whether it is case-sensitive, etc. etc. 

One might know a suggested mechanism for dereferencing a URI with a
specific URI scheme may and if so then there is nothing that prevents
anybody from ever dereferencing a URI but that is entirely outside the
scope of SOAP.

Dereferencing URIs is all about trust - I may trust DNS in order to do
so or I may trust somebody else to dereference it. As such I don't agree
that URI semantics is dangerous in either of the cases you mention: it
is a question of how I establish trust in determining whether a Node can
act in the role that it claims it can.

Henrik Frystyk Nielsen

>-----Original Message-----
>From: noah_mendelsohn@us.ibm.com [mailto:noah_mendelsohn@us.ibm.com] 
>Sent: Tuesday, December 04, 2001 08:07
>To: Henrik Frystyk Nielsen
>Cc: Noah_Mendelsohn@lotus.com; xml-dist-app@w3.org
>Subject: RE: Possible new issue on interpretation of relative 
>URI actors
>The question is not so much about establishing a base, it is about 
>clarifying the responsibilities of a node in assuming a role.
>We have said nothing to indicate that a role is a web 
>resource, or that it 
>is the resource named by the actor URI.  For example, we do nothing to 
>preclude naming a role as the name of some other resource.  Remember, 
>there may be a large number of intermediaries, possibly in different 
>organizations that might want to assume a role like:
>        http://example.org/cachemanagers
>Any resource referenced by the URI is not general at any of the 
>intermediaries assuming the role, and it's almost surely not 
>one accessed 
>via http or that follows the rules for the HTTP scheme.  In 
>that respect, 
>one could argue that following the other rules for resources 
>is dangerous 
>as much as helpful. 
>On the other hand, you might make the case that this is 
>talking about some 
>other resource, but that the assumed role itself is not the 
>resource.  In 
>other words, there's at least in principle a resource, 
>probably at some 
>nth+1st location, and the actor attribute is referring to that 
>In that case, I can see why we should follow the usual URI 
>rules.  I think 
>that's about where you and I would find common ground.
>In any case, I see it as subtle enough that we should indeed 
>say something 
>brief and clear about what's intended.  In other words, to say 
>that roles 
>are indeed web resources (from which follows everything I 
>think you want 
>wrt/ naming).  I'm OK with that.
>Noah Mendelsohn                                    Voice: 
>Lotus Development Corp.                            Fax: 1-617-693-8676
>One Rogers Street
>Cambridge, MA 02142
>"Henrik Frystyk Nielsen" <henrikn@microsoft.com>
>12/04/01 10:54 AM
>        To:     <Noah_Mendelsohn@lotus.com>, <xml-dist-app@w3.org>
>        cc: 
>        Subject:        RE: Possible new issue on 
>interpretation of relative URI actors
>Please have a look at the proposed text for handling xml base 
>which already discusses the question of how to establish a 
>base URI for a message and how to deal with URIs in general. 
>Given that we already have an issue for xml base I am 
>wondering whether we need another issue.
>Henrik Frystyk Nielsen
>[1] http://lists.w3.org/Archives/Public/xml-dist-app/2001Dec/0005.html
>>In private discussion, Henrik and I tripped over the question of a
>>relative URI used as an actor.  If a block has:
>>        Actor="#A"
>>        Actor="A"
>>and if a node decides to act in that role, is there
>>necessarily some other 
>>absolute URI in which role it needs to act?  I had assumed 
>"no", but I 
>>think Henrik had assumed "yes", and he further believes that 
>>no changes to 
>>the SOAP spec are needed, as this is implicit in the web and URI 
>>architecture and the definition of a relative URI.
>>I would prefer to at least be a bit clearer in the spec, say a
>>bit more 
>>about what the base URI for a message might be, etc. 
>>Presumably the base 
>>URI must be stable through message processing, so if you no 
>>how to make #A 
>>absolute, then #B must follow from that and be handled consistently?
>>All of this bears some relation to the dreaded Namespace issue
>>(is it a 
>>string or a real URI) but at least in this case nobody is 
>proposing to 
>>actually retrieve a resource in most cases. 
>>Anyway, I recommend we open an issue.  Thanks.
Received on Tuesday, 4 December 2001 12:12:08 UTC

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