A declarative query language from the W3C for querying
structured propositional data (in the form of
3-tuple [triples] or 4-tuple [quads] records)
stored in a deductive database (colloquially referred
to as triple or quad stores in Semantic Web and Linked Data parlance).
SPARQL is inherently platform independent. Like SQL, the query language and the backend
database engine are distinct. Database clients capture SPARQL
queries which are then passed on to compliant backend
Like SQL for relational databases, it provides a powerful
mechanism for accessing and joining data across one or more data
partitions (named graphs identified by IRIs). The aforementioned
capability also enables the construction of sophisticated Views,
Reports (HTML or those produced in native form by desktop
productivity tools), and data streams for other services.
Unlike SQL, SPARQL includes result serialization formats and an
HTTP based wire protocol. Thus, the ubiquity and sophistication of
HTTP is integral to SPARQL i.e., client side applications (user
agents) only need to be able to perform an HTTP GET against a
URL en route to exploiting the power of
What follows is a very simple guide for using SPARQL against
your own instance of Virtuoso:
Note: the data source URL doesn't even have to be RDF based --
which is where the Virtuoso Sponger Middleware comes into play
(download and install the VAD installer package first) since it
delivers the following features to Virtuoso's SPARQL engine:
Public SPARQL endpoints are emerging at an ever increasing rate.
Thus, we've setup up a DNS lookup service that provides access to a
large number of SPARQL endpoints. Of course, this doesn't cover all
existing endpoints, so if our endpoint is missing please ping
Here are a collection of commands for using DNS-SD to discover
About this entry:
Author: Kingsley Uyi Idehen
Published: 01/16/2011 02:06 GMT-0500
Modified: 01/19/2011 10:43 GMT-0500
Tags: webservices , rdf , semanticweb , linked_data , foaf , sioc , sparql , socialnetworking , windows , dynamic_languages , ruby , ods , openlink , virtuoso , DataSpace
Categories: Demos , Virtual Database , SQL , Semantic Web , Web Services (Web 2.0)
Comment Status: 2
Thanks for posting this :)
I was already at the stage where I'd configured, made and 'make
install'd on OSX, and was wondering what to do next.
post-installation guide and verify installation by typing in the
command: virtuoso -? (if this fails check you've followed
installation and setup steps, then verify environment variables
have been set)"
This didn't work, so I'm a bit stuck. How do I check the right env
vars are set? I tried just opening a fresh terminal, but same
result - n sign of 'virtuoso' command line. I took a look around
the installed files, found
/usr/local/virtuoso-opensource/bin/ contains a 'virtuoso-t'
but that didn't do anything when I ran it...
If using the commercial edition for Mac OS X, you simply use the
applets we provide to start and stop the server. There's no need to
enter the shell.
When using the Open Source edition, you need to have the
~virtuoso-installer dir bin in PATH, then situate yourself in a
directory with a database config file (INI).
Will get the steps above added to the VOS guide as this will
make life simpler.