Great news, this is interesting times for SMW! :) // Samuel
On 04/22/2011 01:37 PM, Markus Krötzsch wrote: > I am happy to announce that SMW now natively supports data > synchronization with any SPARQL-capable RDF store. This email explains > how this works, what the status is, and how interested users can test it > with their own wikis and triples stores. > > It would be helpful if interested users could test the synchronization > with their favourite stores (Virtuoso anybody?). Details are in the > testing section below. > > Cheers, > > Markus > > > > = Detailed Information = > > > == Status == > > The feature is part of the current SMW SVN trunk. This code is still > unstable due to major internal changes that the new functions required. > It is not recommended to use this code yet on sites that are used > productively. In particular, SMW extensions may be break and sporadic > errors may occur. The type Record is currently disabled. I will send > another email later for extension developers. > > > == Upgrade and Downgrade == > > You can install the SVN version as usual. Running the setup > (Special:SMWAdmin or SMW_setup.php script) is recommended. this deletes > some data. Switching back to SMW 1.5.* rthen would require running setup > again (to avoid errors), and doing a full data refresh (to make all > stored data available again). > > You need Curl to be enabled in PHP for the SPARQL connection. This might > require an additional package for you PHP distribution (in Linux). There > are no other dependencies (in particular, we do not use ARC or any other > PHP library for SPARQL support). > > > == Setting up a SPARQL store == > > SMW can synchronize its data with any SPARQL-capable store. This should > work reliably for all editing operations, including page deletions and > updates. To enable this in SMW, you must (obviously) have a running RDF > store. Then add the following lines to your LocalSettings.php (after > loading SemanticMediaWiki.php): > > $smwgDefaultStore = 'SMWSparqlStore'; > $smwgSparqlDatabase = 'SMWSparqlDatabase'; > $smwgSparqlQueryEndpoint = 'http://localhost:8080/sparql/'; > $smwgSparqlUpdateEndpoint = 'http://localhost:8080/update/'; > $smwgSparqlDataEndpoint = 'http://localhost:8080/data/'; > > The last three lines should be the URLs under which your store provides > its various services. The query endpoint is for read queries, the update > endpoint is for SPARQL Update, the optional data endpoint is for the > SPARQL HTTP Graph Management Protocol. You can set the data endpoint to > '' if you do not want to use this service (anything that it does can > also be done via SPARQL Update, but the simpler HTTP Protocol might be > faster). Also, the code for the HTTP Protocol might be specific to > 4Store, so it could be necessary to set it to '' if you use another store. > > This should suffice to make all your page edits to be mirrored in the > default graph of your RDF store. The current implementation does not > distinguish graphs yet, so you can only add to the default graph. You > can try storing a page to see if it works. The URIs used in the store > are the same as in the RDF you get via Special:ExportRDF. If this works, > you can start a data update (Special:SMWAdmin) or run the update script > (SMW_refreshData.php) to add all data to the store. > > > == Testing and Contributing == > > We want to support as many RDF stores as possible, and contributions are > welcome. At the current stage, errors should be apparent in the above > refreshing/updating stage (ideally done on the command line to see the > output for all pages). > > Our current error handling is not extensively tested. Some errors are > ignored silently (especially connection errors that appear to be > temporary) while others are reported. If you find that the updates go > not as expected, then please insert the following code into your > LocalSettings.php: > > $wgExtensionFunctions[] = 'runSparqlTests'; > function runSparqlTests() { > $sdb = smwfGetSparqlDatabase(); > print " Ping (query): " . ( $sdb->ping( > SMWSparqlDatabase::EP_TYPE_QUERY ) ? 'yes' : 'no' ) . "\n"; > print " Ping (update): " . ( $sdb->ping( > SMWSparqlDatabase::EP_TYPE_UPDATE ) ? 'yes' : 'no' ) . "\n"; > print " Ping (data): " . ( $sdb->ping( SMWSparqlDatabase::EP_TYPE_DATA > ) ? 'yes' : 'no' ) . "\n"; > } > > This tries to ping the services that you specified and dumps the result > to the output (obviously, this should only be done on test sites). > > Developers are welcome to have a look at the code in > ./includes/sparql/SMW_SparqlDatabase.php. This file realizes all basic > communication via SPARQL, independent from the concrete RDF/SPARQL that > is used in SMW. It can be used to issue arbitrary SPARQL queries. > Compare it to MediaWiki's Database class. Special adjustments to > individual stores (e.g. using some proprietary feature for COUNT > queries) will be realized by subclassing SMWSparqlDatabase. Such > subclasses could also use PHP APIs to communicate with a store. So > developers who wish to contribute to the SMW triple store support would > mostly work with this code. Likewise, extension developers who want to > use SPARQL would typically talk to this code. > > The "sparql" directory also contains a SPARQL XML result parser and a > container for representing them in PHP. Code that uses SPARQL never will > be bothered with XML or other result formats. The internal presentation > of URIs and literals is done with the objects in > ./export/SMW_ExpElement.php. These objects will also provide a mapping > back to wiki data, soon, to enable further processing in higher levels. > > > == What is next? == > > I will proceed to fully enable SPARQL-based #ask to replace the current > SQL implementation. This will happen within the next few days. The RDF > data stored by SMW has changed slightly and will further change, > typically by adding more information that was currently missing. For > example, redirects and sortkeys are now stored in RDF because they are > needed for #ask. > > In the medium run, one could further move most/all storage activities > from SQL to SPARQL. Currently, the SMWSparqlStore is a subclass of the > SMWSQLStore2, so it keeps the whole SQL database underneath as before. > With SPARQL becoming stable, this could be changed (or a mixed approach > could be chosen that combines the strengths of SQL and SPARQL). > Developers who are interested in this are also welcome to help. > > > > ------------------------------------------------------------------------------ > Fulfilling the Lean Software Promise > Lean software platforms are now widely adopted and the benefits have been > demonstrated beyond question. Learn why your peers are replacing JEE > containers with lightweight application servers - and what you can gain > from the move. http://p.sf.net/sfu/vmware-sfemails > _______________________________________________ > Semediawiki-devel mailing list > Semediawiki-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/semediawiki-devel > > -- Samuel Lampa --------------------------------------- Bioinformatician @ Uppsala University Blog: http://saml.rilspace.org --------------------------------------- ------------------------------------------------------------------------------ EditLive Enterprise is the world's most technically advanced content authoring tool. Experience the power of Track Changes, Inline Image Editing and ensure content is compliant with Accessibility Checking. http://p.sf.net/sfu/ephox-dev2dev _______________________________________________ Semediawiki-devel mailing list Semediawiki-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/semediawiki-devel
