Thank you Sergio, thinks become clearer, I start understanding why you said that our overLOD functionality really looks like LDCache. But there is still a behavior I don't understand. I did load "http://sws.geonames.org/2658434/about.rdf"; not being interested in the file's URI <http://sws.geonames.org/2658434/about.rdf> and its description's triples, but being obviously interested in <http://sws.geonames.org/2658434/>and ( http://sws.geonames.org/2658434/ ) its triples. As this .rdf file contains the two resources, I guess LDCache does try to update both of them, and: - for <http://sws.geonames.org/2658434/about.rdf> it is able to find the file, download it, and extract only the part where <http://sws.geonames.org/2658434/about.rdf> is a subject - for <http://sws.geonames.org/2658434/>, LDCache, without further configuration, is not able to handle the content negociation that happens when opening this URL, and so there is no mention about any update of <http://sws.geonames.org/2658434/> in the log files. Is that correct ? But then, there is something still strange to me: I did also upload my personal foaf file: http://www.websemantique.ch/people/rdf/fabiancretton.rdf This file don't contain any information about the resource <http://www.websemantique.ch/people/rdf/fabiancretton.rdf ( http://www.websemantique.ch/people/rdf/fabcretton.rdf )>, but only about myself: <http://www.websemantique.ch/people/fabiancretton> Nevertheless, LDCache does have the same behavior as for the geonames resource: 09:09:27.023 INFO o.a.m.l.s.p.AbstractHttpProvider - retrieving resource data for http://www.websemantique.ch/people/rdf/fabiancretton.rdf from 'Linked Data' endpoint, request URI is <http://www.websemantique.ch/people/rdf/fabiancretton.rdf> 09:09:27.352 INFO o.a.m.l.s.p.AbstractHttpProvider - retrieved 0 triples for resource http://www.websemantique.ch/people/rdf/fabiancretton.rdf; expiry date: Fri Sep 19 09:09:27 CEST 2014 So where did LDCache find <http://www.websemantique.ch/people/rdf/fabiancretton.rdf> ? I did name the context <http://www.websemantique.ch/people/rdf/fabiancretton.rdf> -> does LDCache also take into account the contexts names ? Another critical aspect about LDCache I'd like (as others I guess) to understand: How does LDCache handle the 'update' of those information ? How does it know that a triple did came from a web resource (and should be updated), and how does it know that a triple was added afterwards (and should be kept for instance) ? Let say I have a bunch of triples with <http://www.websemantique.ch/people/fabiancretton> as a subject. Those triples are loaded from the web. LDCache will do some updates, thus deleting all triples where <http://www.websemantique.ch/people/fabiancretton> is subject, and the reimporting all triples where <http://www.websemantique.ch/people/fabiancretton> is subject, is that correct ? in the mean while, I did add a new triple with <http://www.websemantique.ch/people/fabiancretton> as a subject -> will it be deleted by LD Cache ? Thank you Fabian
>>> Sergio Fernández<wik...@apache.org> 19.09.2014 15:21 >>> On 19/09/14 15:01, Sergio Fernández wrote: >> - why 'retrieved 7 triples'...whereas the context that contains that >> file does have 141 triples ? is this a bug ? or does the algorithm try >> to retrieve only 'modified' triples with the file ? > > That's strange, yes. Internally LDCache would be using something like: > https://gist.github.com/wikier/728e234bb998158bf9ec > > I've just included as a test: > https://github.com/apache/marmotta/blob/b24553cdc877e5f39361c4dd7f0994b46b3ad707/libraries/ldclient/ldclient-provider-rdf/src/test/java/org/apache/marmotta/ldclient/test/rdf/TestLinkedDataProvider.java#L72 > > > And it actually retrieves 7 triples. I'd need to debug why. Well, because at that document there are only 7 triples actually talking about the resource <http://sws.geonames.org/2658434/about.rdf>: http://sws.geonames.org/2658434/about.rdf a foaf:Document ; foaf:primaryTopic <http://sws.geonames.org/2658434/> ; cc:license <http://creativecommons.org/licenses/by/3.0/> ; cc:attributionURL <http://sws.geonames.org/2658434/> ; cc:attributionName "GeoNames"^^xsd:string ; dcterms:created "2006-01-15"^^xsd:date ; dcterms:modified "2012-02-24"^^xsd:date . As I said, LDCache and LDClient work at a resource level, not at the document one. Hope that clarifies the issue. Cheers, -- Sergio Fernández Partner Technology Manager Redlink GmbH m: +43 660 2747 925 e: sergio.fernan...@redlink.co w: http://redlink.co
