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RetrievalMethod

From: Donald E. Eastlake 3rd <dee3@torque.pothole.com>
Date: Thu, 17 Aug 2000 09:40:17 -0400
Message-Id: <200008171340.JAA15971@torque.pothole.com>
To: w3c-ietf-xmldsig@w3.org

I don't recall there being any discussion of Merlin's comments on
RetrievalMethod below.  The main change suggested is to drop the
Method element as it is inherent in the Location URI.  Also, as far as
I know, we have decided to make fields which are always URIs be
attributes and have algorithms be elements with an Algorithm
attribute...  This leads to the following as the most consistent with
the rest of our syntax:

<RetrievalMethod Location="http://..." Type="foo#x509-certificate">
	<Encoding Algorithm="bar#base64">
		<possible-encoding-parameter>...</p.-e.-p.>
	</Encoding>
</RetrievalMethod>

On the other hand, the minimum change would be to simply amend the
current definition by dropping the Method element.

How much implementation is there of RetrievalMethod at this point?
I.E., how much pain is involved in the larger change?

Thanks,
Donald

>At 07:44 PM 7/19/2000 +0100, merlin wrote:
> >
> >r/dee3@torque.pothole.com/2000.07.19/13:40:29
> >
> >>Making some of this stuff optional seems reasonable but I would think
> >>that a lot of implementations would just pass off the uri to some
> >>retrieval mechanism without looking inside it and still want a
> >>separate indication of type and encoding.
> >
> >>Donald
> >
> >I agree. I just don't grasp the reason for the current
> >structure of the element.
> >
> >It seems to me that a minimal specification would be [1]:
> >
> >  <RetrievalMethod Location="http://..."
> >   Type="foo#x509-certificate" Encoding="bar#base64" />
> >
> >A more pedantic specification would be [2]:
> >
> >  <RetrievalMethod Type="foo#x509-certificate>
> >    <Location>http://...</Location>
> >    <Encoding Algorithm="bar#base64" />
> >  </RetrievalMethod>
> >
> >Type could be expanded into an element, if desired.
> >
> >However, I can't see how Type would be more than a URI,
> >nor do I see the impact of Encoding on Type, as captured
> >in the current spec:
> >
> >  <RetrievalMethod>
> >    <Location>http://...</Location>
> >    <Method><x:From-ASN1-To-Key-Info-Foo /></Method>
> >    <Type Encoding="bar#base64"><x:Its-A-X509-Certificate-Foo /></Type>
> >  </RetrievalMethod>
> >
> >As I say, I just don't fully understand what would be a default
> >implementation of the current element specification.
> >
> >Merlin
> >
> >[1]
> >
> ><element name='RetrievalMethod'>
> >  <complexType content='mixed'>
> >    <any namespace='##other' minOccurs='0' maxOccurs='unbounded'/>
> >  </complexType>
> >  <attribute name='Location' type='uriReference' use='required'>
> >  <attribute name='Type' type='uriReference' use='optional'/>
> >  <attribute name='Encoding' type='uriReference' use='optional'>
> ></element>
> >
> >[2]
> >
> ><element name='RetrievalMethod'>
> >  <complexType content='elementOnly'>
> >    <sequence minOccurs='1' maxOccurs='1'>
> >      <element name='Location' type='uriReference' minOccurs='1'
>maxOccurs='1'/>
> >      <element ref='ds:Encoding' minOccurs='0' maxOccurs='unbounded'/>
> >    </sequence>
> >    <attribute name='Type' type='uriReference' use='optional'/> 
> >  </complexType>
> ></element> 
> >
> ><element name='Encoding'>
> >  <complexType content='mixed'>
> >    <any namespace='##other' minOccurs='0' maxOccurs='unbounded'/>
> >    <attribute name='Algorithm' type='uriReference' use='required'/>
> >  </complexType>
> ></element>
> >
> >>From:  merlin <merlin@baltimore.ie>
> >>Message-Id:  <200007182220.XAA10671@bobcat.baltimore.ie>
> >>To:  "Joseph M. Reagle Jr." <reagle@w3.org>
> >>Cc:  "IETF/W3C XML-DSig WG" <w3c-ietf-xmldsig@w3.org>
> >>In-reply-to:  <3.0.5.32.20000718162839.00ad5e70@localhost> 
> >>Date:  Tue, 18 Jul 2000 23:20:57 +0100
> >>
> >>>r/reagle@w3.org/2000.07.18/16:28:39
> >>>>At 19:30 7/18/00 +0100, Merlin Hughes wrote:
> >>>> >The Schema has mandatory content for the Type element. This
> >>>> >seems wrong because it can't then be implemented interoperably
> >>>> >without further specification.
> >>>> 
> >>>>Are you suggestion it be change to optional?
> >>>>
> >>>>   <element name='Type'>
> >>>>     <complexType content='mixed'>
> >>>>       <any namespace='##other' minOccurs='0' maxOccurs='unbounded'/>
> >>>>        ...
> >>>
> >>>Something of that nature. RetrievalMethod simply seems
> >>>underspecified given that it "SHOULD" be implemented.
> >>>By making some of those parts optional, it could be
> >>>read as minimally and sufficiently specified.
> >>>
> >>>For example, it seems reasonable to present a RetrievalMethod
> >>>with the Location:
> >>>
> >>>  ldap://ldap.baltimore.ie/CN=merlin?userCertificate;binary
> >>>
> >>>What, in this case, do I specify as the Method and Type,
> >>>both of which are currently mandatory?
> >>>
> >>>By making Method and Type optional I can, at the very least,
> >>>assume that the recipient will determine the type of key
> >>>information from the URI.
> >>>
> >>>Merlin
> >>>
> >>
> >
>
>_________________________________________________________
>Joseph Reagle Jr.   
>W3C Policy Analyst                mailto:reagle@w3.org
>IETF/W3C XML-Signature Co-Chair   http://www.w3.org/People/Reagle/

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Received on Thursday, 17 August 2000 09:37:31 GMT

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