Hi,
I have the following feature suggestion for the WG.
Feature: Ability to Construct a List or Collection
Feature Description:
At present it is not possible to construct or reconstruct an
rdf:List or an RDF container of an
arbitrary size in a SPARQL CONSTRUCT query. This means that
CONSTRUCT cannot be used to
reconstruct some data that exists in the graph, nor can it be used
to create some legal forms of
RDF.
A DESCRIBE query is only a viable alternative only if the
collection/container is a bnode and the default
algorithm generates a bounded description that includes the list
contents. But even then not all of
the desired context (e.g. properties of the list members) would be included.
Example
Don't have a concrete example of this in practice. It may be that a
combination of assignment to a
variable (to create the container or collection resource), and then
application of a property function
similar to that implemented in ARQ would enable this.
Existing Implementations
None that I'm aware of. ARQ's property functions only cover
iteration/access over members of the
container/collection not construction.
Use Cases
Remove the current restrictions on being able to CONSTRUCT RDF
Container/Collections.
The primary example of where this was an issue was with working with
a bibliographic dataset in which
the Table of Contents for an issue of a journal or a book was
modelled as an RDF List (i.e. as an ordered
collection with a fixed membership). It was not possible to write
CONSTRUCT queries to extract the information
required to present a user interface showing all the desired data.
The work around was to use a CONSTRUCT
with ARQ list extensions to get the core data, a SELECT query and
custom code to reconstitute the structure
of the original list, and then a merge of the data graphs. Support
for list construction in the query language
would avoid the need for the extra code and queries.
Cheers,
L.
--
Leigh Dodds
Programme Manager, Talis Platform
Talis
leigh.dodds@...
http://www.talis.com
