Thanks, Scott, that helps clarify the usage model. Unfortunately, I'm still having some issues.
1. My database contains named graphs which correspond to ontologies; this is a feature SDB permits to allow you to reference an ontology stored in the database rather than having to load from a file. When I create the connection, I got an error that it couldn't find one (out of four) referenced ontologies in the database. The resulting connection didn't find much of anything. 2. So, I imported the ontologies into my project from the files before creating the connection. This seemed to work better, but the resulting "Ontology Overview" complains that there are multiple owl:Ontologies in the model. It's not entirely clear from the popup explanation what it does in this case and how to work around it. 3. Finally, I was able to run my query, but the GRAPH ?g returned is always the root URI of my database. Is this because the UnionGraph connection essentially copies everything into the default graph, thereby losing the "?g" info? 4. It still doesn't work to re-open a connection file one has created and saved. The error is as reported in my first message. The only workaround is to create a new connection file with a different name or restart TBC. 5. Bug report: very few of your windows, most importantly error message pop-ups, permit you to copy/paste out of them. Makes life tedious. Thanks, Dave On Apr 6, 1:34 pm, Scott Henninger <[email protected]> wrote: > Ok, thanks for the clarifications. The first thing to understand is > that these examples are created from a database perspective where the > query is applied to a database with some named graphs. When using > TopBraid Composer or Live, you are using a server perspective where > there can be multiple database references, file serializations, etc. > To access a named graph in one of those databases necessarily involves > a level of indirection: you need to identify the database and the > named graph. > > For SDB, there are three different contexts for named graphs to > consider: > 1) an unnamed graph - this is a separate graph that does not have a > name (triples only, not a quad) > 2) a named graph (quad storage) > 3) the union of all graphs > > Note that 1) and 3) are different. The union graph will include the > unnamed graph and all named graphs. > > Given this, you can set the context of a query to the union graph for > the SDB database with the FROM statement in SPARQL: > > SELECT * > FROM <base URI of union graph> > WHERE { > GRAPH ?g {?s ?p ?o} > > } > > The second step is to get the base URI of the union graph for your SDB > data store. To do this create a connector file (New > Jena SDB > connector) that specifies "urn:x-arq:UnionGraph" as the SDB Named > Graph URI. > > The use of connector files may need a bit of explanation. It's key to > understand that Composer/Live use a named graph structure throughout > its workspace, using the base URI as the name of the graph. This not > only addressed the indirection necessary to address multiple > databases, but integrates nicely with owl:imports which also uses URIs > to identify the imported graphs. Each connector creates a base URI > that holds information about what data set (where a "data set" can be > anything that has a named graph structure) to address and the named > graph within that data set. This goes for the union graph, which is a > specific type of graph in SDB, as well as named (and unnamed) graphs. > > Again, the added level of indirection is necessary because Composer is > using a server model (workspace consisting of many connections) and > the examples are using a single data store model (one connection). > > -- Scott > > On Apr 6, 9:58 am, DaveL <[email protected]> wrote: > > > > > > > > > Scott, > > > I am using TBC 3.4.0. > > > The general form of the query was taken > > fromhttp://www.cambridgesemantics.com/2008/09/sparql-by-example/#%2833%29 > > . > > > The exact query I am running (slightly edited to remove propriety > > information) is: > > > PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> > > PREFIX cc: <http://anchor/example#> > > SELECT * > > WHERE > > { > > { ?s rdf:type cc:exampleType } > > UNION > > { GRAPH ?g { ?s rdf:type cc:exampleType } } > > > } > > > The intent is to return all named graphs which contain resources of > > rdf:type "exampleType." > > > This query works perfectly when executed via the Jena/SDB > > QueryExecution class, by code (excerpted) here: > > > Dataset ds = DatasetStore.create(store); // an SDB Store > > Query query = QueryFactory.create("---the above query---")); > > QueryExecution qe = QueryExecutionFactory.create(query, ds ); > > try { > > ResultSet rs = qe.execSelect(); > > ResultSetFormatter.out(rs); > > } finally { > > qe.close(); > > } > > > Thanks for any comments, > > > Dave > > > On Apr 5, 6:23 pm, Scott Henninger <[email protected]> wrote: > > > > Dave; We'd need a couple of follow-up to look into this properly. > > > First is what version of TBC-ME are you using? The second is what > > > specific query template are you using? > > > > To access an existing SDB database, you'd need to use the same New > > > > RDF/OWL Jena SDB Database Connection, and fill in the information on > > > the relational database where the data is store. Note that this > > > wizard only creates a connection to an existing data store. There > > > aren't any stricter requirements for using a .sdb connector. > > > > -- Scott > > > > On Apr 5, 3:24 pm, DaveL <[email protected]> wrote: > > > > > Having read the discussion last month about Named Graphs, I find > > > > myself still a bit confused. > > > > > I'm developing an OWL app which uses SDB as the repository. In the > > > > repository are many Models which are named graphs representing > > > > resources, and some Models which are ontologies (referenced by the > > > > resources, via the SDB DocumentManager). > > > > > I tried connecting to this pre-existing store from TBS (Maestro > > > > Edition), and had a couple of odd results. > > > > > First, if I create the .sdb file using the wizard under New / RDF/OWL > > > > Jena SDB Database Connection, I can access the default graph (if I > > > > don't fill in the "Named Graph URI" field, or any specific graph if I > > > > put its URI in the field, but there doesn't appear to be a way to > > > > access the database as a whole. For example, I'd like to be able to > > > > query for all graphs which contain a triple matching a pattern. The > > > > template for doing this (in the SPARQL by example presentation) > > > > doesn't work for me. > > > > > Second, re-opening an existing .sdb file never seems to work. An > > > > exception is invariably thrown: > > > > > "Could not load \TopBraid\SDBRepository.sdb or one of its imports. > > > > The most recent URI washttp://localhost/dataStore > > > > No matching StoreCache entry found" > > > > > Once I get this error I must restart TBS before I can look at the > > > > database again. > > > > > Any guidance on what this means? Are there stricter requirements for > > > > the contents of the database than I am aware of, for example? (Things > > > > I must add to be TBS-compatible, for example. I note a reference in > > > > the .sdb file to a "config" model that I don't create...) > > > > > Thanks, > > > > > Dave Lebling -- You received this message because you are subscribed to the Google Group "TopBraid Suite Users", the topics of which include TopBraid Composer, TopBraid Live, TopBraid Ensemble, SPARQLMotion and SPIN. 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