- From: Steve Harris <S.W.Harris@ecs.soton.ac.uk>
- Date: Thu, 20 May 2004 17:24:24 +0100
- To: DAWG public list <public-rdf-dawg@w3.org>
This is a use case from Nick Gibbins, the guy who write the generic RDF browser for 3store. It coveres optional binding and presumably tell-me-about + a number of other things. - Steve ----- Forwarded message from Nick Gibbins <nmg@ecs.soton.ac.uk> ----- > The Advanced Knowledge Technologies project has built a general-purpose RDF > browser that complements its 3store RDF repository. This browser makes use > of the query facilities provided by 3store to present the contents of a > knowledge base in a human-readable fashion, and on a per-resource basis. > > 1. Browser basics > > A browsing session begins with the user making a simple query that specifies > either a resource URI, or a literal value that is to be searched for: > > http://triplestore.aktors.org/browse/ > > If a literal query is executed, the browser displays all the resources that > have a literal-valued property whose value matches that given in the query: > > http://triplestore.aktors.org/browse/?literal=Gibbins > > If a resource query is executed, the browser displays all the information > that the repository holds on that resource: > > http://triplestore.aktors.org/browse/?resource=http%3A%2F%2Fwww.ecs.soton.ac.uk%2Finfo%2F%23person-01269 > > This information is displayed in two columns; the left column lists the names of > those properties which have values for this resource, and the right column lists > the values of those properties. Both incoming and outgoing properties (which > point to or from the resource under examination) are displayed. The former are > displayed with a left-pointing arrow to indicate that they have the reverse > sense (the value displayed is the subject of the triple, rather than the > object). The triple patterns which are used to generate this view for a resource > query are as follows: > > (RESOURCE, ?property, ?value) > (?value, ?property, RESOURCE) > > where RESOURCE is the resource URI given in the browser query > > 2. Optional matching > > If a resource-valued property is displayed, the browser preferentially displays > a human-readable name for the property value by searching for rdfs:label triples > for that value. If no such label exists, the URI of the resource is displayed. > > When this behaviour is combined with the queries from the previous section, we > would like to be able to specify a single query which matches statements > involving the queried resource, and the relevant human-readable names, if any exist: > > (RESOURCE, ?property, ?value) > (?value, <rdfs:label>, ?label) > > REQUIREMENT: it should be possible to specify that certain triple patterns > within a query are optional > > 3. Statement origins and source provenance > > The information presented by the browser may have originated in more than > one RDF file. The browser is able to indicate the origins of each statement > presented, depending on whether the user has chosen to show sources, or > hide sources. We refer to the source of a statement as its origin or context. > Such an origin will typically be the URI of the RDF file from which the > statement originated, which provides a mechanism for attaching coarse-grained > provenential metadata to statements, by making statements about the origin URI. > This adds a third column to the browser display, which displays the name of the > source for each statement. > > http://triplestore.aktors.org/browse/?resource=http%3A%2F%2Fwww.ecs.soton.ac.uk%2Finfo%2F%23person-01269&showSource=1 > > [[[ given that 'context' is a seemingly contentious word, probably best to only > refer to 'origin' or 'source' here. > > also, we're assuming that the granularity of statement origins is file-level; > proposals for alternative RDF syntaxes which allow for multiple named graphs > within one file will change this ]]] > > REQUIREMENT: it should be possible to determine the origins of the statements > which satisfy a given triple pattern > > [[[ in 3store, we have extended RDQL syntax to add an optional fourth component > to each triple pattern that is bound to the URI of the origin of matching > statements. there may be other suitable approaches to satisfying this > requirement, so we've been circumspect in the language we've used here ]]] > > 4. Distinct query answers > > If the sources are hidden, and the browser is displaying multiple > statements which are identical, and differ only in their origins, only one > statement is shown. > > REQUIREMENT: It should be possible to specify whether only distinct answers to a > query are to be returned. > > [[[ the analogy here is with SELECT DISTINCT in SQL ]]] ----- End forwarded message ----- -- Stephen Harris 07970 557047 AKT, IAM Research Group 023 8059 8347 University of Southampton, UK swh@ecs.soton.ac.uk http://www.aktors.org/
Received on Thursday, 20 May 2004 12:24:31 UTC