ID recap

[Ray Plante]

Hi,

I've gotten a couple of queries about whether we came to a concensus on 
identifiers, and if so, what was it.  The answer to the first is yes, for 
the most part (though discussion remains open through the standardization 
process).  

Here's a summary of what the main ideas as I understand them.  I am 
working on a Working Draft that will spell it out in more detail.

1.  IVOA identifiers refer to registered resources.  Given an IVOA ID, one 
    should be able to resolve it to a description of the resource it 
    refers using some registry.

2.  IVOA IDs have two forms: an XML form and a URI form.

3.  The IVOA ID has two components:  an AuthorityID and a ResourceKey

4.  The AuthorityID... 
    o  establishes a namespace for related resources
    o  is "owned" or controled by an organization the manages the 
         resources within the namespace.
    o  must be uniquely "owned".  This standard does not define the 
         mechanism by which AuthorityIDs are ensured or encouraged to be 
         unique or their ownership otherwise assertained.  It is expected 
         that a central IVOA authority service of some kind will be 
         necessary to check for ownership.
    o  is recommended to be in the form of a DNS hostname.  
    o  will be limited in the characters that can be used to form it.

5.  An organization may "own" several AuthorityIDs as it deems useful.

6.  The ResourceKey...
    o  is an identifier to a specific resource relative to the namespace 
         set by the AuthorityID. 
    o  is in complete control of the organization "owning" the 
         AuthorityID. 
    o  will be limited in the characters that can be used to form it.

7.  The XML form of the ID will look like this:

    <ResourceID>
      <AuthorityID>adil.ncsa.uiuc.edu</AuthorityID>
      <ResourceKey>surveys/96.JC.01</ResourceKey>
    </ResourceID>

8.  The URI form will look something like this:

      ivo://adil.ncsa.uiuc.edu/surveys/96.JC.01

Other notes:
  *  Record-level Keys were dropped from this proposal as it was thought 
       that the requirements for rendering components of a resource may be 
       different in different contexts.

  *  Can IDs have semantic content?  They can but they are not recognized 
       within the context of this IVOA standard

  *  IDs do not address the problems of transience or replication.  These 
     will be addressed in a separate recommendation built on top of 
     registries and this ID standard.

cheers,
Ray