On 09/06/15 16:55, Charles Greer wrote:
Hi all,
I'm trying still to wrap my head around Dataset and DatasetGraph.
My intention is to support MarkLogic XA transactions over SPARQL queries and
graph operations.
I see only a locking mechanism for DatasetGraph, not transaction boundaries.
In order to support transactions with a custom backend, it seems to me that I
will have to provide a custom Dataset
implementation, not only a DatasetGraph.
Is this correct? Thanks, Charles
You could implement Dataset directly but it's not the ideal way to do it
(IMO).
As a general style-thing, Jena does have interfaces for
Dataset/Model/Statement/Resource/Literal, which form the API but the
core system is DatasetGraph/Graph/Triple/Node. Extending at the
Dataset/Model is very unusual.
The single implementation of Dataset is DatasetImpl that goes:
protected DatasetImpl(DatasetGraph dsg)
{
this.dsg = dsg ;
if ( dsg instanceof Transactional )
this.transactional = (Transactional)dsg ;
}
i.e. it dynamically checks the DatasetGraph for the Transactional interface.
I have suggested all DatasetGraph are sort-of Transactional [1].
class MarkLogicDSG implements DatasetGraph, Transactional
There are several frameworks under DatasetGraph though may not not as
useful to you.
Andy
[1]
http://mail-archives.apache.org/mod_mbox/jena-dev/201506.mbox/%3C5575EBA6.2040106%40apache.org%3E
https://issues.apache.org/jira/browse/JENA-957
DatasetGraphWithLock - no real abort.
Actually, using RDF Patch [2] and recording undo actions, abort can be
done but it's not zero cost in terms of memory which might have knock-on
effects to apps.
[2] http://afs.github.io/rdf-patch/
Charles Greer
Lead Engineer
MarkLogic Corporation
[email protected]
Cell: +1 707 318 0442
@grechaw
www.marklogic.com
