values of Type

[Johannes Ernst]

Thanks, Drummond, for the clarification.

On Dec 6, 2005, at 23:16, Drummond Reed wrote:

> Sorry for the delay -- was out at my son's soccer tournament tonight.
>
> Answers:
>
> 1) In the XRD schema, the Type element takes a value of type "anyURI".
> However it is important to note that according to the W3C XML spec,  
> this can
> be either absolute or relative. So *technically* Andy's example is not
> incorrect.
>
> However I fully agree that Type values SHOULD be absolute in order  
> to reduce
> the potential for collision. So Andy's examples SHOULD have
> "+authentication" and "+photos", as these are absolute XRIs. (Note  
> that
> these are equivalent to "xri://+authentication" and "xri:// 
> +photos", i.e.,
> the "xri://" part is optional with absolute XRIs that start with  
> global
> context symbols (=, @, +, $, !. This was conscious design decision to
> simplify human usability, e.g., to type a global XRI in an editor  
> or address
> bar only requires a single symbol character.)
>
>
> 2) The purpose of the MediaType element does not overlap with the  
> purpose of
> the Type element (and Andy's example of "isso" as a media type is  
> incorrect
> -- we're talking IANA-registered media types here, like "text",
> "application/xml", etc.). In XRI resolution (and potentially for other
> applications using XRDs), MediaType is just further metadata  
> available to
> describe the capabilities of a service endpoint.
>
> Hope that helps.
>
> =Drummond
>
> -----Original Message-----
> From: Johannes Ernst [mailto:jernst+lists.danga.com at netmesh.us]
> Sent: Tuesday, December 06, 2005 2:06 PM
> To: Drummond Reed
> Cc: Dale Andy; YADIS List
> Subject: values of Type
>
> Drummond,
>
> I'm just looking through Andy's XDI slides from his presentation
> yesterday that I unfortunately had to miss. A question arises.
>
> One of his examples contains the following XML fragment.
>
> <service>
> 	<type>authentication</type>
> 	<URL>http://www.idp.com/</URL>
> 	<mediaType>isso<mediaType> 	
> <service>
> <service>
> 	<type>photos</type>
> 	<URL>http://www.kodakgallery.com/AlbumMenu.jsp</URL>	
> 	<mediaType>img<mediaType>
> <service>
>
> Which, apparently and not surprisingly, instantiates the same XML
> format as we do in YADIS. However, it appears to me that there are
> two significacnt distinctions in use:
>   - YADIS assumes that the value of "type" is a URL, such as http://
> lid.netmesh.org/sso/1.0
>   - Andy's slides seem to assume that "mediaType" (not used in YADIS)
> is a very substantial attribute that, in this use, seems to partially
> overlap with what we use the URL for for YADIS purposes.
>
> So ... this poses some or all of the following questions:
> 1) did I get it wrong?
> 2) does the current draft standards document prescribe one or the
> other, and if so which?
> 3) if it doesn't prescribe one or the other, does the document need
> to be tightened so interoperabilty is realistic?
>
>
> Johannes Ernst

Johannes Ernst
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