On 18/09/2010 18:35, Samuel Lampa wrote: > On 09/18/2010 03:22 PM, Markus Krötzsch wrote: >> On 18/09/2010 15:05, Alfredas Chm wrote: >>> As the first thing on the agenda, I would like to ask Markus to create a >>> page (and add permissions) on the semantic-mediawiki.org >>> <http://semantic-mediawiki.org> to put the info on the separate >>> extensions, comparisons - to be used later as the basis for the discussion. >> >> Done (at least a stub): >> >> http://semantic-mediawiki.org/wiki/SPARQL_and_RDF_stores_for_SMW > > Great! Had interesting read on > http://semantic-mediawiki.org/wiki/SPARQL_and_RDF_stores_for_SMW#Realisation > > Especially this section drew my attention: > http://semantic-mediawiki.org/wiki/SPARQL_and_RDF_stores_for_SMW#Modifying_the_SMW_store_API_and_implementations_to_use_RDF_stores > > ... so let me add some inline comments (This might be aspects you were > discussing/regarding already, but just to make sure): > > Wikipage wrote: >> ... needs to be extended with a function that takes SPARQL queries and that >> returns SMW query result objects > > For this kind of processing SPARQL/RDF etc with PHP, I'd like to > highlight the huge benefit of keeping ARC2 in the picture ... it has > really been an amazing productivity igniter, not so much for its RDF > store and SPARQL Endpoint as for its super-convenient data structures > and methods for processing SPARQL, RDF (and its variants). I cannot > imagine having succeeded with RDFIO in time without all that and there > also seems to be quite some converge on ARC2 as the library-of-choice > for other PHP based projects as well (The upcoming Drupal 7, which has > RDF export turned on by default, etc.)
The core of SMW should not be dependent on ARC2, though. The idea is to completely delegate SPARQL processing to the external store, and to keep SPARQL queries opaque to SMW. The only new SPARQL syntax processing required in SMW would be the processing of SPARQL query result documents. They are probably not so hard to parse, but one could also consider copying code from ARC2 to get this done. AFAIK existing extensions that implement RDF store bindings in this way did not require much extra RDF/SPARQL handling code for this approach. > > Though maybe that is what was thought of, with the line further below: >> Direct bindings to ARC2 (via PHP) I would appreciate to have support for using local ARC2 stores directly through PHP, without running it as a web service. This would also allow some of the RDFIO code to move to SMW Core (the SMW-SPARQL-Update functionality via SMWWriter would remain an extension, but could possibly be integrated with SMWWriter). > > Anyway, so next thing: > >> Generic SPARQL/SPARUL SMW store implementation that can connect to different >> RDF stores supporting these standards > > Noting though that there are currently more than one standard for > updating. ARC2 currently uses SPARQL+ [1], while waiting for > SPARQ:/Update to stabilize, and standards seem to be a bit of a moving > target still, so it'd probably be good to make things as generic as > possible, in order to support multiple/changing standards. Yes, and it might be necessary to do some changes to the update language before the recommendation is completed. In the worst case, this would reduce our "generic" RDF store support to one or two systems that support our preliminary version of the SPARQL update language. But as soon as SPARQL 1.1 is out, these intermediate restrictions will vanish (and the main architecture of SMW's SPARQL support would not be affected by this). > > In general, all these envisioned strategies seem to require ability to > run more than one store. So, is that possible today (There is the > $smwgDefaultStore config setting, but that only takes one store AFAIK, etc)? I do not plan to use multiple SMWStore objects at the same time now. The RDF store bindings will work like the current implementations: as write-through extensions of an SQL-based store (the SQL binding will be simpler since the query part is fully delegated to the RDF store, but copies of annotations will still be kept locally). Regards, Markus ------------------------------------------------------------------------------ Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev _______________________________________________ Semediawiki-devel mailing list Semediawiki-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/semediawiki-devel
