Single or collection resources

[Douglas Tody]

On Thu, 6 Aug 2009, Ray Plante wrote:

> In closing, I'll note that the DAL services aren't currently good for finding 
> data based on the science subject matter that the datasets address.  If we 
> consider our goals of re-purpose data, then perhaps they shouldn't; science 
> happens arguably at a higher level.  The only other service for doing 
> discovery by subject matter is the registry.  We could use some improvements 
> that allow a user to effectively make the jump between the very general and 
> the dataset.

My feeling is that, except for limited metadata such as a target
classification which is specific to a given observation, this issue
of science subject matter is best dealt with at the level of an
entire data collection.  Hence the full problem of data discovery
would involve first finding data collections of interest (primarily a
semantic query although coverage may also be important), followed by
querying the individual collections for individual datasets (primarily
a quantitative query).  Then finally we get to the actual data access.
When people start with the DAL services then usually they already
know which collections they want to access.

This more detailed information on data collections needs to be
maintained in the registry where collections are described, registered,
and searched.  However I think we may need more sophisticated tools
to use this information for end-user discovery queries.

 	- Doug