Service metadata

There is a cross-group issue regarding provision of service metadata. The metadata ought to be available from any registry but some services will only provide minimal (core) metadata to the registry and will make extended metadata (e.g. table and column information wrt tabular data services) available via service method.

Those registries which will endeavour to maintain fine-grained information will have to periodically poll services to ensure their metadata is up to date.

The question is whether ALL services must provide full metadata information via some standard interface method.

Or only those services which do not keep detailed metadata up to date in the registry should provide this extended metadata.

I would propose that the basic service interface for ALL VObs services should OPTIONALLY include a method which returns FULL service metadata as a single registry metadata document, including all the service metadata extension information which is made optional in the registry. If a service does not support this method then it is assumed that someone will keep the registry up to date for that service with full extension metadata.

I would also note that in the future it will be expected that all IVOA service workgroups will develop their own registry extensions and will document this as part of the service specification. The registry workgroup will only in the future look at the wider registry issues.

Cheers,
Tony.

__
Tony Linde
Phone: +44 (0)116 223 1292 Mobile: +44 (0)7753 603356 Fax: +44 (0)116 252 3311 Email: Tony.Linde-at-leicester.ac.uk Post: Department of Physics & Astronomy,

        University of Leicester
        Leicester, UK   LE1 7RH
Web:    http://www.star.le.ac.uk/~ael
            
Project Manager, EuroVO VOTech   http://eurovotech.org 
Programme Manager, AstroGrid     http://www.astrogrid.org