Data and services

[Doug Tody]

On Fri, 12 Sep 2003, Tony Linde wrote:

> Can I suggest some naming rules (bit rich since I'm not an astronomer) to
> avoid confusion. 
> 
> Everything referred to by a registry entry is a resource, uniquely and
> globally identified by a ResourceId.

Yes - registries register resources, which should include both services
and data (and possibly other things).
 
> A service is anything which is invocable, ie is a web service with callable
> methods.

Yes.
 
> A data collection is any set of data which can be queried.

A data collection is a logically-related grouping of datasets.

> A sky service is a service which provides access to a data collection.

I think we should omit this term - it belongs in the application domain.
That is, a service implementor might define something they call a sky
service (or many other types of services) but these are not registry
concepts.  The registry will be used to register such services, but it
doesn't "know" about them.
 
> A dataset is any addressable part of a data collection. Access to the
> dataset is via the sky service of the data collection.

The first statement is ok.  More formally a dataset is a structured
data object which we treat as a unit in terms of data management, e.g.,
a FITS image.

	- Doug