----- Original Message ---- > From: Kingsley Idehen <kide...@openlinksw.com> > To: Peter Ansell <p_ans...@yahoo.com> > Cc: virtuoso-users@lists.sourceforge.net > Sent: Tuesday, 17 February, 2009 12:25:17 AM > Subject: Re: [Virtuoso-users] constructing URI's from literals > > Peter Ansell wrote: > > > > ----- Original Message ---- > > > >> From: Kjetil Kjernsmo > >> To: virtuoso-users@lists.sourceforge.net > >> Sent: Monday, 16 February, 2009 6:01:17 PM > >> Subject: Re: [Virtuoso-users] constructing URI's from literals > >> > >> On Monday 16 February 2009 06:23:59 Peter Ansell wrote: > >> > >>> Hi, > >>> > >>> Is there anyway with SPARQL and Virtuoso to create a URI in a result when > >>> it is stored as a literal in the triplestore? > >>> > >> I don't know if Virtuoso has something, but looking at > http://www.w3.org/TR/rdf-sparql-query/#FunctionMapping > >> > >> it appears that you cannot cast from string to URI, only from URI to > >> string. > >> > > > > I was hoping that wasn't the only case and that there was a virtuoso > > extension > to allow people to do the reverse if it is reasonable. The resulting URI > would > only be used in the output, ie, not in a further graph match, so it doesn't > sound technically unfeasible from a naive viewpoint. > > > Peter, > > I think Ivan's example covers the output scenario (i.e, the last CONSTRUCT > example). > > For instance does the following demonstrate the end product of your use case > i.e., what you would like to achieve output wise e.g. a URI for a specific > CNAME without changing the actual original Bio2Rdf URIs in the Quad Store, a > kind of reverse re-write rule: > > http://linkeddata.openlinksw.com:8891/geneid:1043922 (this URI doesn't exist > in > the Quad store it is simply used as the mechanism for local de-referencing of > using the local data in the Quad store which has bio2rdf cname URIs).
That isn't completely what I want, but that would be useful in some cases. I was more wanting to utilise the xsd:anyURI typed literal's as the subject of RDF statements that come out as a result of a construct (or in your example it might be a describe), and was unable to do so without the Virtuoso SPARQL extensions. My research work is around providing the URI based access to multiple endpoints based on deconstructing the URI and figuring out what REST service the URI refers to (in your example with a custom URI it would be a simple construct but I view that as a general case of a broader framework). The endpoints aren't necessarily SPARQL, and the user may not always want rdf, that is just part of the framework I guess. It is also nice to be able to have more than one function attached to a particular REST URI, for instance I want to automagically retrieve the tags I have put on an item whenever I dereference the item's URI, see the current bio2rdf servers for that functionality. If you dereference http://qut.bio2rdf.org/geneid:1043922 for instance you should get a document which contains triples related to http://bio2rdf.org/geneid:1043922 and any tags which may have been applied to that item... one of which I made up just now for demonstration purposes. Even though there is access provided to the specific mirror via that URI, in order to keep the URI's which people use identical I would prefer that at least some single domain name was used for all of the bio2rdf URI's, but if people are utilising the system completely privately, and understand that other people will generally be communicating using the http://bio2rdf.org/ URI's then it is fine for them to have personal optimisations IMHO. Note that currently we are having troubles with the network being overloaded and we don't have infrastructure to setup the mirrors in enough places so that the public traffic will fall sufficiently, hence the geneid may not actually resolve to the record if we are trying to stabilise the network by not forcing more requests on the geneid sparql endpoint for a little while. Cheers, Peter Make Yahoo!7 your homepage and win a trip to the Quiksilver Pro. Find out more
