Scope of registry

[Giaretta, DL (David)]

The simplest service in this that context is probably
   CanYouAnswerThis( some text )
which a Registry would send to every resource on its list - delegating the
question it received.

A Registry itself could have a service "PleaseAddMeToYourList" which an
external resource could use to get itself added to a Registry's list of
things to send message to.

The OAI verbs provide a high level "back-end" protocol, which optimises how
a registry would work and gather information.

However in my previous email I was refering to the "front-end" of the
Registry service(s) i.e. what can clients get from a  Registry e.g. "tell me
everything you know about area of sky X?" or "where is the best place to
join catalaog Y to catalog Z?" or "who do I ask to get access to resource
B?" or "how do I convert magnitude-A to magnitude-b?"

Once we get those front-end questions sorted out then some of the
optimisation-type (back-end) questions should become clearer.

..David


-----Original Message-----
From: Roy Williams [mailto:roy at cacr.caltech.edu]
Sent: 06 February 2003 15:44
To: Giaretta, DL (David) 
Cc: registry at ivoa.net; metadata at us-vo.org
Subject: Re: Scope of registry


> We surely need to define what services the Registry should
> provide - and recognise that we don't need to make an
> exhaustive list now because we should be able to extend it.
> All registries need to sign up to this set of services -
> or at least be able to specify what sub-set it adheres to

In the OAI model, there are exactly six verbs that the registry understands.
The verbs are:

Identify (who are you)
List Metadata Formats (what schemas do you have for metadata)
List Sets (collections hosted by this repository)
List Identifiers (return just the identifiers and dates of most recent
change)
List Records (return full records)
Get Record (return a full record from its identifier).

This is a pretty basic set of services!

If a registry has an OAI interface, it can have others too. ArXiv and ADS
brought up OAI long after they had their native interfaces.

In addition to OAI, we would need to define and implement a query language
using additional verbs. If, for example, we define each survey by its sky
coverage, then OAI provides no way to ask for every survey that covers
Orion.

Roy

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