Eureka moment! It returns a new Graph of a certain type. Whereas I need the graph node to determine where the underlying data is.
Cheers Dick. On 15 March 2016 at 11:28, Andy Seaborne <[email protected]> wrote: > On 15/03/16 10:30, Dick Murray wrote: > >> Sorry, supportsTransactionAbort() in AFS-Dev >> <https://github.com/afs/AFS-Dev>/src >> <https://github.com/afs/AFS-Dev/tree/master/src>/main >> <https://github.com/afs/AFS-Dev/tree/master/src/main>/java >> <https://github.com/afs/AFS-Dev/tree/master/src/main/java>/projects >> <https://github.com/afs/AFS-Dev/tree/master/src/main/java/projects>/dsg2 >> <https://github.com/afs/AFS-Dev/tree/master/src/main/java/projects/dsg2>/ >> *DatasetGraphStorage.java* >> > > *Experimental code.* > > > > supportsTransactionAbort is in the DatasetGraph interface in Jena. > > > DatasetGraphStorage is using TransactionalLock.createMRSW > > As mentioned, it needs cooperation from the underlying thing to be able to > do aborts and MRSW does not provide that (it's external locking). > > DatasetGraphStorage doesn't presume that the storage unit is transactional. > > After these discussions I've decided to create a DatasetGraphOnDemand which >> extends DatasetGraphMap and uses Union graphs. >> >> However in DatasetGraphMap shouldn't getGraphCreate() be >> getGraphCreate(Node graphNode) as otherwise it doesn't know what to >> create? >> > > It creates a graph - addGraph(graphNode, g) is managing the naming. Grapsh > don't know the name used (in other places one graph can have many names). > > DatasetGraphMap is for a collection of independent graphs to be turned > into a dataset. > > Andy > > >> @Override >> public Graph getGraph(Node graphNode) >> { >> Graph g = graphs.get(graphNode) ; >> if ( g == null ) >> { >> g = getGraphCreate() ; >> if ( g != null ) >> addGraph(graphNode, g) ; >> } >> return g ; >> } >> >> /** Called from getGraph when a nonexistent graph is asked for. >> * Return null for "nothing created as a graph" >> */ >> protected Graph getGraphCreate() { return null ; } >> >> Dick. >> >> >
