Single or collection resources

[Mark Taylor]

On Thu, 6 Aug 2009, Markus Demleitner wrote:

> Dear DAL folks,
> 
> On Thu, Aug 06, 2009 at 06:28:44AM -0500, Ray Plante wrote:
> > collection separate from the services that access it.  In VOResource  
> > speak, the former is a resource of type DataCollection, the latter would  
> > be a CatalogService with an SIA capability.  The DataCollection resource  
> > can reference the service as a "related resource" (of the type  
> > "served-by").  This allows for N DataCollections being registered, but  
> Yes, that's nifty, and I'd probably like to go this way.  Except:
> 
> > One barrier to this approach is the extent to which registries support  
> > it.  That is, your registry will need to let you (easily) set the related  
> ...and in particular, what VOExplorer does with it.  I always find
> that people are much more impressed when their data turns up in a
> "real" program as opposed to "just another website".  So -- I'd be
> really grateful if someone from from the VOExplorer team could
> comment what would work best for them.  In particular, do you even
> look at DataCollections?  Will you show your nice service icons for
> served-by?

Markus,

sorry for the delay in responding to this, I've been a bit busy.

VOExplorer does display DataCollection resources from the registry,
and gives them their own special little icon.  If the DataCollection 
(or any other resource) contains vr:Relationship elements 
(consisting of a relationshipType/relatedResource pair, where 
relationshipType is "served-by" or any of the other possibilities - see 
sec 3.1 of http://www.ivoa.net/Documents/REC/ReR/VOResource-20080222.html)
they will be displayed in a "Relationships" section in VOExplorer's
Information tab for the resource.  The related IVORN is shown as a link, 
which if clicked on pops up another VOExplorer window showing the
related resource.  However the nature of the related resource 
(whether it's a cone search or whatever) would not be displayed 
in the DataCollection resource; you have to click on the link to 
find that out.

See the record for "ivo://wfau.roe.ac.uk/iras-dsa/wsa/ceaApplication"
as an example.  This one has a "related-to" rather than "served-by" 
relationship, but you get the idea; the content of the relationshipType 
element is not treated specially in any case.

One could imagine displaying in the relationship line the service
capabilities of any related resources along with their IVORNs.
However, this could not be done simply by examining the vr:Relationship
element in the DataCollection record, since there's not enough 
information there to determine the service type of the related resource.
So, such functionality would require lookup and analysis of the
related records themselves, which is probably not a good idea
(you'd need to decide what foreign details should be displayed,
and it would confuse the current model that what's displayed in
the resource information is just information stored in that resource).

To address Ray's point about registry support; I think that the 
AstroGrid registry would be quite happy with a DataCollection resource
having several relatedResources, but non-XML-based registries may have 
more rigid ideas of what resources can be related to what other 
ones and in what way.

Mark

--
Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
m.b.taylor at bris.ac.uk +44-117-928-8776 http://www.star.bris.ac.uk/~mbt/