[Esip-preserve] On Earth Science Data File Uniqueness

[Ruth Duerr]

Well this has been an interesting discussion today.  I've heard good compelling arguments for two competing best practices for using UUID's (Chris' use of a message digest form of UUID and Curt's pure Unique Identifier form of UUID).  Both seem to be variants on the Unique Identifier use case from the assessment paper with different implications for provenance (Chris's a Unique Identifier with trust value and Curt's a Unique Identifier with provenance value).  I also suspect that there are actually many more use case and use case variants than we've even heard about yet.  I think that this just reinforces one of the conclusions of the paper, that multiple identifiers will absolutely be required.  

As for Bruce's question - if all I have is a Unique Identifier (and no Unique Locator) how do I find the file and all the rest of the information about it - that's always been a problem, one that Unique Identifiers by definition have nothing to say about.  In order to have received the file, someone somewhere must have had the Unique Locator - they should have passed that along either explicitly or within the metadata...  If they didn't, oh well.... maybe a Google search for the UUID will help or maybe you should go back and ask them for it. 

Ruth

On Feb 9, 2011, at 12:27 PM, Bruce Barkstrom wrote:

> My argument is "where do you go to get metadata when
> all you've got is an ID?"  UUID's are fine - but certainly don't
> contain redirection addresses.  To paraphrase, "knowing that
> this file is called 'Bob' doesn't tell me which family to call to
> find out where I should return him, nor does it tell me what
> format he's in."  So where do we get that.  In human terms,
> where do we find his birth certificate?  This is kind of an inverse
> to the problem "given an ID, where do I find a file?" which is the
> locator use case problem.  This one is "I've got an ID and a file,
> where do I go to find out about if if that's all I've got?"
> 
> Bruce B.
> 
> On Wed, Feb 9, 2011 at 10:21 AM, Curt Tilmes <Curt.Tilmes at nasa.gov> wrote:
> On 02/09/11 10:14, Bruce Barkstrom wrote:
> > The question on my mind is sort of "If you come across a file with a
> > UUID, who produced it?"
> 
> I agree, that is an important question and needs to be addressed, but
> UUID doesn't address it, nor was it intended to.
> 
> > This isn't quite the same as the unique locator use case in the
> > paper, since the question isn't "which sources could provide me with
> > an authentic copy of a particular kind of file?"  It's more along
> > the line of "where did this fellow 'Bakak' come from?"
> 
> Sure, but without the identifier, you would still have the question
> "where did this fellow come from?"  to which the response is "Who are
> you talking about?"
> 
> The identifier at least allows you to refer to him by name..
> 
> Is your argument that we SHOULD have good metadata (I agree), or that
> we SHOULD NOT assign UUIDs?
> 
> Curt
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