[ogsa-wg] Re: latest ws-naming draft (Re: [ogsa-naming-wg] One more thing)

[Frank Siebenlist]

Hi Mark,

I've split-up your previous message and only comment on your second 
point here.
(...hoping that Tom will answer the more difficult first part ;-) )

Mark McKeown wrote:
> ...
>> * include a recipe for generation of a single IRI from the Address and
>> ReferenceParameters that can function as an identifier of the resource.
>> Mark Mc Keown pointed at the W3C Web Architecture description of the use
>> of URIs which we could borrow from.
>>     
>
> I am not sure about creating an IRI from the wsa:Address and the
> wsa:ReferenceParameters. Consider the following EPRs
>
> <wsa:EndPointReference>
>   <wsa:Address>http://grid.org/jobs/4654</wsa:Address>
>   <wsa:ReferenceParameters>
>        <DateCreated>Thu Nov 17 16:05:43 UTC 2005</DateCreated>
>   </wsa:ReferenceParameters>
> </wsa:EndPointReference>
>
> and
>
> <wsa:EndPointReference>
>   <wsa:Address>http://grid.org/jobs/4654</wsa:Address>
>   <wsa:ReferenceParameters>
>        <DateCreated>Thu Nov 17 13:07:53 UTC 2005</DateCreated>
>   </wsa:ReferenceParameters>
> </wsa:EndPointReference>
>
> If DateCreated is just to inform the service when the EPR was created
> and is not used by the service for anything else then the two
> EPRs are for the same WS-Resource. However if I create a name based
> on a combination of the wsa:Address and wsa:ReferenceParameters I will
> get two different names, ie I have created URI aliases and divided
> the network losing some of the goodness of Metcalfes law [7].
>   

That is a good example when the generated identifier would be less 
useful for comparison.

However, I'm afraid that it is not particular to the use of RefParams, 
because another minter may choose to embed that time-stamp inside of the 
Address' IRI and then the ability to compare identical resources through 
the Address alone would also fail.

This should probably be part of a "recommended use" or "best practices" 
section where we can discourage such use and explain why.

Regards, Frank.

-- 
Frank Siebenlist               franks at mcs.anl.gov
The Globus Alliance - Argonne National Laboratory