URLs?

[Ray Plante]

Hi Rob,

congratulations on what I'm sure was a good meeting.

On Thu, 8 Dec 2005, Rob Seaman wrote:
> We've  
> attempted to adopt the larger IVO standard in this case as in others,  
> but while STC, for example, is having to prove its specific worth to  
> VOEvent, our packet identifiers have not.

I'm sensing that perhaps an argument has been put forward 
suggesting that IVOA IDs is not a good choice or that URLs has an inherent 
advantage.  Is there some context you could summarize for me?

The role of an identifier is to allow one to unambigously refer to the 
thing being identified (in this case an event).  The important 
characteristics that you want from an identifier to achieve this
  1.  guaranteed global uniqueness (throughout time)
  2.  non-reusibility; that is, the event an identifier points to never 
         changes.  

IVOA IDs provide exactly this:  the namespace-ing provided by the 
authority ID and the supporting registry framework maintain global 
uniqueness and disallow reuse.  Since IVOA IDs (the part before the #) 
must be registered, you establish traceability between the event and a 
person responsible for it.  This is traceability is not so clear with URLs 
or other arbitrary URIs.  

The previous proposal for the ID had another added benefit.  It
recommended that the part before the # refer to the event registry service
that is capable of resolving the identifier to the actual event message.  
This service, by virtue of using the ivo: URI scheme, must be registered
in an IVOA Resource Registry.

I probably missed some compelling discussion, but this seems like a 
no-brainer to me.  

cheers,
Ray