PUBLIC MARKS with tags SPARQL & rdf

D2R Server is a tool for publishing relational databases on the Semantic Web.

It enables RDF and HTML browsers to navigate the content of the database,

and allows applications to query the database using the SPARQL query language.

Summary: As more data is being stored in RDF formats like RSS, a need has arisen for a simple way to locate specific information. SPARQL, a powerful new query language fills that space, making it easy to find the data you need in the RDF haystack. Take a tour of SPARQL's features and learn how to use SPARQL queries from your own Java™ applications with the Jena Semantic Web Toolkit.

By providing open access to increasing amounts of Linked Data, public SPARQL endpoints are boosting the growth of the Semantic Web by providing great data for you to use in your applications. As with many other data-driven Web sites out there, a Web page can be created by sending a query to these endpoints and then wrapping the results in HTML tags; the big difference for SPARQL endpoints is the public availability of this new data for your applications. This article shows how simple CGI scripting can get data from two different SPARQL endpoints to build applications that answer your user's questions about actors shared between two directors and which musicians have released which albums.

Leigh Dodds, Platform Programme Manager, gives the following screencast to demonstrate using the Talis Platform to use rich RDF features on the BBC’s /programmes and /music sites.

A property path expression (or just 'path') is similar to a string regular expression but over properties, not characters. ARQ determines all matches of a path expression and binds subject or object as appropriate. Only one match is recorded - no duplicates for any given path expression, although is the path is used in a situation where it's initial points is already repeated in a pattern, then this duplication is preserved.

RegExp ou XPath appliqué à un graphe? Intéressant, mais peut-être abscons.

For the finder part I have implemented a SPARQL backend, which internally delegates to Sesame2, which is the same default index/query that is used to find Entities in general. This in itself is pretty cool, because it means that you can write your domain model in Java, have it be automatically persisted in a store like Neo4j, and then with no extra effort expose it through SPARQL for AJAX webapps to consume (both RDF/XML and JSON output is supported today). Minimally writing a domain model only involves writing Java interfaces (no classes), so it's pretty easy to get started.