ARQ - A SPARQL Processor for Jena

ARQ is a query engine for Jena that supports the SPARQL RDF Query language. SPARQL is the query language developed by the W3C RDF Data Access Working Group.

ARQ Features

• Standard SPARQL
• Free text search via Lucene
• SPARQL/Update
• Access and extension of the SPARQL algebra
• Support for custom filter functions
• Property functions for custom processing of semantic relationships
• Aggregation, GROUP BY and assignment as SPARQL extensions
• Support for federated query
• Support for extension to other storage systems
• Client-support for remote access to any SPARQL endpoint

Introduction

• A Brief Tutorial on SPARQL
• Application API - covers the majority of application usages
• Frequently Asked Questions
• ARQ Support
• Application javadoc
• Command line utilities
• Logging
• Explaining queries
• Tutorial: manipulating SPARQL using ARQ

Advanced SPARQL use

Features of ARQ that are legal SPARQL syntax.

• Free text searches
• Accessing lists (RDF collections)
• Extension mechanisms
  • Filter Functions
  • Property Functions

• Library

  • Filter function library
  • Property function library

• Writing ARQ FILTER functions

• Querying remote SPARQL services
• Constructing queries programmatically
• ARQ and the SPARQL algebra
• Extending ARQ query execution and accessing different storage implementations

Extensions

Feature of ARQ that go beyond SPARQL syntax. The default query language is standard SPARQL. These features require the query to be parsed with an explicit declaration of Syntax.syntaxARQ.

• Property paths
• GROUP BY and counting
• SELECT expressions
• Sub-SELECT
• Negation
• LET variable assignment
• Basic federated query
• Conditions in FILTERs

Update

ARQ supports the W3C standard SPARQL Update language as well as the precursor submission to W3C. Using the standard is preferred; support for the submission is for legacy use.

• SPARQL Update
• SPARQL/Update Submission
• The ARQ SPARQL/Update API

See Also

• Joseki - Server implementation of the SPARQL protocol.
• TDB - A SPARQL database for Jena, a pure Java persistence layer for large graphs, high performance applications and embedded use.
• SDB - A SPARQL database for Jena, using SQL databases.

W3C Documents

• SPARQL Query Language specification
• SPARQL Query Results XML Format
• SPARQL Protocol

Articles

Articles and documentation elsewhere:

• Introducing SPARQL: Querying the Semantic Web (xml.com article by Leigh Dodds)
• Search RDF data with SPARQL (by Phil McCarthy) - article published on IBM developer works about SPARQL and Jena.
• SPARQL reference card (by Dave Beckett)
• Parameterised Queries with SPARQL and ARQ (by Leigh Dodds)
• Writing an ARQ Extension Function (by Leigh Dodds)

Miscellaneous Resources

• Turtle - a non-XML RDF serialization

Online Demo

Online Query Form for experimenting with SPARQL queries.