[Esip-preserve] On Earth Science Data File Uniqueness

[Bruce Barkstrom]

The uniqueness of UUID's wasn't the question.  The point was that if
the generator gave out "Bob", "Bill", "Jane", and so on, if there weren't
a place to find out about who created the object and when, the identifier
is simply another bunch of digital garbage in the file or the result set
from the database.  In other words, the ID's have a "social function".

Bruce B.

On Wed, Feb 9, 2011 at 7:48 AM, Curt Tilmes <Curt.Tilmes at nasa.gov> wrote:

> On 02/07/11 10:45, Bruce Barkstrom wrote:
> > Here's another wrinkle: if a UUID is formed in the field but no one
> > registers it someplace what good is the identifier?
>
> UUIDs have some nice properties.  They are globally unique forever and
> can be generated on the fly in the field without any central
> authority.
>
> If I get a chunk of data (from anywhere -- capture from an instrument,
> generate from some data transformation, create on the fly --
> anything), I want to tag it with something permanent that I can attach
> to it that will follow and distinguish that chunk of data forever.
>
> With UUID, I don't have to register anywhere (though I can, and it
> would add to their usefulness), or ask for someone to make/assign me
> an id, or anything.  I just make them.  It takes trivial computation
> to make as many of them as I would ever need at any point of data
> collection or generation.
>
> If you don't want to make them yourself, you can even get them from
> many places around the internet.
>
> Here's one such place: http://uuid-service.appspot.com/?output=plain
>
> They're giving them out for free!  As many as you want.  They've got
> plenty, don't worry about them running out.
>
> They aren't tied to any controlled namespace or naming authority.  You
> don't have to check with anyone, or go through hours of naming
> discussions or anything prior to making them.  (I would bet we spent
> hundreds of man hours on MODIS naming conventions and many people
> still hate them.)
>
> If I can persistently tie that tag -- that identifier -- to that chunk
> of data.  I can always tell it apart from any other chunk of data in
> the world.  I can always compare two tags and tell if the two objects
> are the same.
>
> (Note, these are my "pro-UUID" arguments -- I've previously posted
> "anti-UUID" arguments, which exist as well.)
>
> > Also, I think we need to be a lot more sensitive to the kinds of
> > "objects" we're trying to identify.
>
> Agree 100%.  I think this will fall out of the "Provenance and Context
> Content Standard".  We will identify and organize a comprehensive list
> of "objects" and recommend for each one of them how we will identify
> them.  In that hierarchy, one of the "objects" will be "data
> granules", and one of the identifiers for them (there will be more
> than one) should probably be UUID (based on the conclusions of the
> identifiers analysis work).
>
> Curt
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