JRDF (Java RDF)

JRDF is an attempt to create a standard set of APIs and base implementations to RDF (Resource Description Framework) using the latest version of the Java language. The API will cover anything that is deemed to be useful for Java programmers. A key aspect will be to ensure a high degree of modularity and to follow standard Java conventions. It will be similar to other standard Java APIs such as JDBC, XML, Collections, etc.

Current Java APIs for RDF have some drawbacks and many strengths. Some do not follow the current RDF specification exactly or lack features that are appropriate to certain use cases. Also, there are many common aspects to existing APIs with only slight differences in method names, package hierarchies and exception handling.

APIs Provided

JRDF has the following features (or will have in the near future):

A Graph API (including graph comparison and graph set-based operations),
Creating and manipulating Graph objects (Statements, Resources, Nodes, etc.),
In memory and disk based graphs with a standard system level interface for storing triples,
IoC support (currently using Spring 2),
RDF Datatypes,
Local (where nodes are tied to a graph/store) and global (where they are not) RDF statements,
An RDF to Java object API (similar to Hibernate or Sesame's Elmo), and
Query Handling including SPARQL support (including results, transport, etc).

Future features may include:

Transactions,
Event Handling (addition/removal of nodes from a graph),
Security, and
Inferencing.

Being able to talk directly to a triple store in a common manner with the ability to swap differing implementations is one of the key aims of the project. There are obvious benefits, especially when running in the same JVM, that a common API provides. At the same time it will allow higher level APIs to be developed on top of the existing agreed upon APIs.

Existing Work

This project is based on the existing RDF libraries and is designed to include the best features from all available sources.

Other standard APIs will be used where possible.

Documentation

Wiki

Documentation is being developed on Google Code.

Getting Started

Wiring and Entry Points in JRDF

Relational SPARQL Operations

Publications

Honours Thesis, Querying the Semantic Web using a Relational Based SPARQL (HTML, PDF).

Dataset used was scutter.rdf ( 100K, 50K, 25K).

Javadoc

Status

05/02/2008 - JRDF 0.5.4 - Fixed btree bug and added Resource methods for easier triple addition/removal.
23/01/2008 - JRDF 0.5.3 - Improved find() performance, finds by node type, bug fixed in RDF/XML parser, allow Literals and URI directly across graphs, and other bug fixes.
22/11/2007 - JRDF 0.5.2 - Improved performance and support for reading writing large RDF/XML files (millions of triples).
09/11/2007 - JRDF 0.5.1 - Improved Bdb implementation and db4o support added. Bugs fixed with the Resource API and data type support.
26/08/2007 - JRDF 0.5.0 - Java 6 support. New APIs for Persistence, Resources and data types.
05/06/2007 - JRDF 0.4.1.1 and SPARQL GUI 0.3.1.1 - Bug fix release for wiring errors.
27/02/2007 - SPARQL GUI 0.3.1 - Syncs with 0.4.1 release.
27/02/2007 - 0.4.1 - First source release with SPARQL implementation, RDF/XML Writer, and NTriples pull and push parser.
16/11/2006 - SPARQL GUI 0.3 - Removes bug associated with project.
20/08/2006 - SPARQL GUI 0.2 - Removes bugs associated with parsing SPARQL and produces correct results for OPTIONAL and UNION DAWG test cases.
13/08/2006 - SPARQL GUI 0.1 - A simple GUI that allows user's to submit SPARQL queries. Supports a subset of SPARQL: PREFIX, pattern matching, UNION, join (.) and OPTIONAL.
24/06/2006 - 0.3.4.3 - Bug fix release for 0.3.4 branch. XML Literal parsing regression bug.
03/04/2006 - 0.4.0 - First Java 1.5 only release. Began work on relational and graph operations. Began work on NTriples parser and SPARQL support. RDF/XML improved to add proper handling of XML Literals, relative URIs and xml:base processing.
24/11/2005 - 0.3.4.2 - Another bug fix release. Fixes to RDF/XML literal parsing and NTriple escaping.
08/10/2005 - 0.3.4.1 - Bug Fix Release. Fixes to xml:base handling and resolving of relative URIs.
12/07/2005 - 0.3.4 - RDF/XML parser based on RIO released (with improved support for blank nodes), start of SPARQL and remote query support, bugs fixed, and general code refactoring and preparation for move to Java 1.5.
27/09/2004 - 0.3.3 - Single bug fix - correction to reification semantics. No changes to API.
14/09/2004 - 0.3.2 - Further in memory bug fixes and improved iterator support.
23/08/2004 - 0.3.1 - In memory bug fix release.
15/08/2004 - 0.3 - In memory implementation, visitor support, collection and container support.
21/02/2004 - 0.2.1 - Updated graph, added vocabularies and iterator for results.
18/12/2003 - 0.2 - Update of graph level interface.

Details

Contact: Andrew Newman
Project Page: JRDF