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

Re: Possible new issue on interpretation of relative URI actors

From: Christopher Ferris <chris.ferris@sun.com>
Date: Wed, 05 Dec 2001 14:10:32 -0500
Message-ID: <3C0E7128.4090508@sun.com>
To: Noah Mendelsohn <noah_mendelsohn@us.ibm.com>
CC: skw@hplb.hpl.hp.com, Doug Davis <dug@us.ibm.com>, henrikn <henrikn@microsoft.com>, xml-dist-app <xml-dist-app@w3.org>
+1

Noah Mendelsohn wrote:

> The religion here comes from the fact that URI's and resouces are arguably
> the two most fundamental abstactions on the web, with quite carefully
> crafted standards regarding their interpretation.  So, if you have a
> document with a base URI, and relative URI references, Web architecture
> suggests that the relative forms should really be made absolute before use.
> This also ensures that if a retrievable resource is used to, e.g., describe
> a role, that the resouce can be consistently retrieved using both absolute
> and relative forms.
> 
> ------------------------------------------------------------------------
> Noah Mendelsohn                                    Voice: 1-617-693-4036
> Lotus Development Corp.                            Fax: 1-617-693-8676
> One Rogers Street
> Cambridge, MA 02142
> ------------------------------------------------------------------------
> 
> 
> 
> 
> 
>                                                                                                                       
>                     "Williams,                                                                                        
>                     Stuart"                  To:     "'Christopher Ferris'" <chris.ferris@sun.com>                    
>                     <skw@hplb.hpl.hp.        cc:     Noah Mendelsohn/CAM/Lotus@Lotus, Henrik Frystyk Nielsen          
>                     com>                     <henrikn@microsoft.com>, xml-dist-app@w3.org, Doug                       
>                     Sent by:                 Davis/Raleigh/IBM@IBMUS                                                  
>                     xml-dist-app-requ        Subject:     RE: Possible new issue on interpretation of relative URI    
>                     est@w3.org               actors                                                                   
>                                                                                                                       
>                                                                                                                       
>                     12/05/01 12:31 PM                                                                                 
>                                                                                                                       
>                                                                                                                       
> 
> 
> 
> 
> Hi Chris,
> 
> I had a slightly more subtle read of Noah's issue, in that I thought that
> he
> was asking where in fact two roles were being denoted by the use of a
> relative URI in an actor. ie does actor="#A" imply distinct roles "#A" and
> "http:/foo.org/#A"
> 
> From Noah's message:
> 
>>>I am OK with drawing the conclusion that any node that acts in role #A
>>>must (or should, if you prefer) act in some corresponding absolute URI
>>>role as well.
>>>
> 
> The trailing "as well" is suggestive of an 'additional' role as opposed to
> "#A" and http://foo/#A" being different ways to denote the same single
> role.
> 
> Personally I'm a same single role kind of a person myself :-)
> 
> My 0.02,
> 
> Stuart
> 
> 
>>-----Original Message-----
>>From: Christopher Ferris [mailto:chris.ferris@sun.com]
>>Sent: 04 December 2001 21:47
>>To: Doug Davis
>>Cc: Noah Mendelsohn; Henrik Frystyk Nielsen; xml-dist-app@w3.org
>>Subject: Re: Possible new issue on interpretation of relative
>>URI actors
>>
>>
>>I didn't interpret it that way. What I took away from
>>this is that the following are equivalent w/r/t the
>>actor role identified.
>>
>><S:Envelope xmlns:S="..." xml:base="http://foo/">
>>   <S:Header>
>>   <X:A S:actor="#bar" xmlns:X="...">
>>   </S:Header>
>>   <S:Body/>
>></S:Envelope>
>>
>><S:Envelope xmlns:S="...">
>>   <S:Header>
>>   <X:A S:actor="http://foo/#bar" xmlns:X="...">
>>   </S:Header>
>>   <S:Body/>
>></S:Envelope>
>>
>>
>>My $0.02,
>>
>>Chris
>>
>>Doug Davis wrote:
>>
>>
>>>Noah, are you suggesting that "http://foo/" and "http://foo/#A"
>>>should be equal w.r.t. determining roles?  I don't believe
>>>that are (or should be) equal.
>>>-Dug
>>>
>>>
>>>Noah Mendelsohn/CAM/Lotus@Lotus@w3.org on 12/04/2001 03:18:48 PM
>>>
>>>Sent by:  xml-dist-app-request@w3.org
>>>
>>>
>>>To:   "Henrik Frystyk Nielsen" <henrikn@microsoft.com>
>>>cc:   Noah Mendelsohn/CAM/Lotus@Lotus, xml-dist-app@w3.org
>>>Subject:  RE: Possible new issue on interpretation of
>>>
>>relative URI actors
>>
>>>
>>>
>>>No problem.  Although we use slightly different words, I think we are
>>>
> in
> 
>>>general agreement.  URI's reference resources, by definition.  I am OK
>>>with drawing the conclusion that any node that acts in role #A must (or
>>>should, if you prefer) act in some corresponding absolute URI role as
>>>well.  A consequence of this decision is, for a given absolute AbsU, a
>>>node acting in #A and #B must act as either both AbsU#A and AbsU#B or
>>>neither.  I think we should call that out with at least a note.
>>>
>>>
>>>
>>--------------------------------------------------------------
>>----------
>>
>>>Noah Mendelsohn                                    Voice:
>>>
>>1-617-693-4036
>>
>>>Lotus Development Corp.                            Fax:
>>>
>>1-617-693-8676
>>
>>>One Rogers Street
>>>Cambridge, MA 02142
>>>
>>>
>>--------------------------------------------------------------
>>----------
>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>"Henrik Frystyk Nielsen" <henrikn@microsoft.com>
>>>12/04/2001 01:05 PM
>>>
>>>
>>>        To:     <noah_mendelsohn@us.ibm.com>
>>>        cc:     <Noah_Mendelsohn@lotus.com>, <xml-dist-app@w3.org>
>>>        Subject:        RE: Possible new issue on interpretation of
>>>relative URI actors
>>>
>>>
>>>
>>>I apologize if my mail seemed a bit sharp in the language - I should
>>>have eaten something first.
>>>
>>>Henrik
>>>
>>>
>>>
>>>>-----Original Message-----
>>>>From: Henrik Frystyk Nielsen
>>>>Sent: Tuesday, December 04, 2001 09:12
>>>>To: 'noah_mendelsohn@us.ibm.com'
>>>>Cc: 'Noah_Mendelsohn@lotus.com'; 'xml-dist-app@w3.org'
>>>>Subject: RE: Possible new issue on interpretation of relative
>>>>URI actors
>>>>
>>>>
>>>>
>>>>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
>>>>mailto:henrikn@microsoft.com
>>>>
>>>>
>>>>
>>>>>-----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
>>>>>resource.
>>>>>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:
>>>>>1-617-693-4036
>>>>>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
>>>>>mailto:henrikn@microsoft.com
>>>>>
>>>>>[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"
>>>>>
>>>>>or
>>>>>
>>>>>      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 Wednesday, 5 December 2001 14:14:44 UTC

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