Could a user use a POST SM module to enable a workaround? Not as clean, but might get the job done for 3.1 demos.
On Oct 8, 11:47 am, Holger Knublauch <[email protected]> wrote: > Hi David, > > yes this is a known issue. The underlying problem is that in SPARQL > 1.0 there was not clean mechanism to specify a SPARQL end point. This > was left out of the query syntax. However, in many cases it is highly > desirable to be able to write this inside of a query, e.g. in SPIN > rules or other queries that are stored in the model. For these > reasons, I have re-purposed the FROM keyword. However, this is also > not really the correct solution, and some SPARQL end points complain > about this (although they could also just ignore this). > > Now, with the upcoming TBC 3.2 the situation is different because > Jena's ARQ engine now has a much cleaner mechanism to specify the > SPARQL end point, using the SERVICE keyword > > http://jena.sourceforge.net/ARQ/service.html > > For the next TBC release, I have deactivated the FROM work-around and > instead users will be able to use SERVICE (even to mix-and-match > remote queries with other queries - an extremely cool feature, thanks > for Andy Seaborne). > > Until then, I am sorry to say there is no work-around. > > Holger > > On Oct 8, 2009, at 7:57 AM, David Park wrote: > > > > > > > Ok. Great demo on how to use dbpedia as a public sparql endpoint. From > > within TBC, I can > > SELECT * > > FROM <http://dbpedia.org/sparql> > > WHERE { > > <http://dbpedia.org/resource/Washington_Metropolitan_Area> ?p ?o . > > } > > > Yet when I attempt to many of the other endpoints published in > >http://esw.w3.org/topic/SparqlEndpointsand > >http://www.freebase.com/view/user/bio2rdf/public/sparql, I have no > > success. > > > I know that some of those endpoints are down or are not returning any > > data, but the ones hosted using D2RQ/Joseki are of interest to me, and > > I've found that any attempt to query one of these sparql endpoints > > results in the message: > > HTTP 400: This service does not allow the dataset to be specified in > > the query > > > Once I started poking around in Joseki, I discovered that the default > > processor does not allow the user to specify a named graph, whether > > using "FROM" or "FROM NAMED" clauses. > > > If I have diagnosed this correctly, what is happening is that TBC is > > taking a query such as: > > SELECT ?s ?p ?o > > FROM <http://www4.wiwiss.fu-berlin.de/dailymed/sparql> > > WHERE { > > ?s dailymed:name "cortisone" . > > ?s ?p ?o . > > } > > ORDER BY ?s > > > And shipping it off, in toto, to the sparql endpoint > >http://www4.wiwiss.fu-berlin.de/dailymed/sparql > > > Since the SPARQL protocol allows for specifying a named graph using > > the FROM clause, I can understand why TBC would pass this through, > > since the protocol allows for naming graphs, so here are some > > questions: > > > 1) Is the use of a SPARQL endpoint as a named graph in a FROM clause > > compliant with the W3C > > recommendationhttp://www.w3.org/TR/rdf-sparql-protocol/? > > > 2) If so, then since the protocol allows for specifying named graphs, > > and a given SPARQL endpoint could be hosting multiple graphs (not the > > current Joseki implementation, but an OpenVirtuoso implementation, > > perhaps) Wouldn't it be more practical, if TBC wants to allow the user > > to specify the endpoint in the FROM clause to identify the SPARQL > > endpoint then strip it out from the FROM clause? > > > 3) If not, then shouldn't the TBC SPARQL query widget allow the user > > to specify an endpoint via some other means than the FROM clause? > > > I am currently on an assignment to assess the usefulness of Semantic > > Web tools. One of the things the company I am on assignment to is > > really excited about is the ability to discover "external information" > > as it relates to their internal information. Since the majority of > > public endpoints currently rely on the D2R/Joseki implementation, > > wouldn't it be in TopQuadrant's best interest to have a means whereby > > one might query these endpoints from within the tool, to demonstrate > > its usefulness outside of the academic graph one might be using > > locally? > > > Since I cannot do this with TBC, I have to instead rely on custom > > development using Jena or god forbid Python in order to fit this bill. > > I was hoping to show how some quick and dirty SPARQLMotion components > > could snag some awesome data from linkedct, dailymed, drugbank and > > diseasome. > > > Thanks for your consideration.- Hide quoted text - > > - Show quoted text - --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "TopBraid Composer Users" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/topbraid-composer-users?hl=en -~----------~----~----~----~------~----~------~--~---
