On ID "sameness"

[Roy Williams]

Perhaps we could ask how to assign ID's to the Cone Seraches that have been
registered (http://voservices.org/cone/register/showlist.asp).

The answer is obvious -- it is the person who sets up the registry. He can
use a sequence of numbers, a hash from the metadata, or name them after his
favorite Greek Gods. I name this Cone Search "Zeus". IMHO, we (the VO
community) are NOT in a position to influence this choice, it is made by
repository owners.

Our role, however, is to "globalize" the choice that was made, by providing
a namespace for the chosen identifiers. This could be assigned by the NVO
project, perhaps "CSReg". To get this identifier of a repository from NVO,
there must be documents explaining what is meant by this identifier
(documents, WSDL, OAI information, etc etc).  Similarly, NVO is registered
with IVOA as a repository of astronomical information.

Thus the global ID is a sequence of tokens of decreasing scope, each dreamed
up by a different person/committee, and each token has an implied
documentation bundle that goes with it. For example
    IVOA:NVO:CSReg:Zeus

Therefore I believe the ID question devolves to a question of what
documentation bundle goes with one of the tokens.

"Sameness" is a matter of compring ID strings. If they are different, we
must look to their metatdata for any possible relationships. We should not
overload our ID with extra stuff and try to be all things to all people.

Roy



--------
Caltech Center for Advanced Computing Research
roy at cacr.caltech.edu
626 395 3670