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, including javascript 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
• Querying remote SPARQL services
  • HTTP Authentication for ARQ
• Logging
• Explaining queries
• Tutorial: manipulating SPARQL using ARQ
• Basic federated query (SERVICE)
• Property paths
• GROUP BY and counting
• SELECT expressions
• Sub-SELECT
• Negation

Features of ARQ that are legal SPARQL syntax

• Conditions in FILTERs
• Free text searches
• Accessing lists (RDF collections)
• Extension mechanisms
  • Custom Expression Functions
  • Property Functions
• Library
  • Expression function library
  • Property function library
• Writing SPARQL functions
• Writing SPARQL functions in JavaScript
• Custom execution of SERVICE
• Constructing queries programmatically
• Parameterized query strings
• ARQ and the SPARQL algebra
• Extending ARQ query execution and accessing different storage implementations
• Custom aggregates
• Caching and bulk-retrieval for SERVICE

Extensions

Feature of ARQ that go beyond SPARQL syntax.

• LATERAL Join
• RDF-star
• Operators and functions MOD and IDIV for modulus and integer division.
• LET variable assignment
• Order results using a Collation
• Construct Quad
• Generate JSON from SPARQL

Update

ARQ supports the W3C standard SPARQL Update language.

• SPARQL Update
• The ARQ SPARQL/Update API

See Also

• Fuseki - 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.
• RDFConnection, a unified API for SPARQL Query, Update and Graph Store Protocol.

W3C Documents

• SPARQL Query Language specification
• SPARQL Query Results JSON 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)

RDF Syntax Specifications

• Turtle
• N-Triples
• TriG
• N-Quads