The latest version of dotNetRDF is now released to the public, this is version 0.1.2 Alpha (Official build number is 0.1.2.16009). This release adds many bug fixes and improvements to the library some of which are summarised below:

• General Improvements
  • Many bug fixes and minor optimisations
  • Further improved in-memory storage for Triples with various indexing strategies used
• Parsing Improvements
  • Added parsers for TriX and NQuads
  • New static FileLoader class which allows you to load a Graph from a file without first instantiating a Parser
• Query Improvements
  • Major bug fixes to the SPARQL engine so most complex queries are now answered correctly
  • Experimental support for various SPARQL 1.1 working draft features
  • Indexing used to improve performance significantly
  • Support for natively querying any of the supporting backing Stores
• Serialization Improvements
  • Added writers for TriX and NQuads
  • Improved the FastRDFXMLWriter so that it writes nicer looking syntax, still not as nice as the other RDF/XML writers but far faster
• Storage Improvements
  • Support for AllegroGraph
  • Support for 4store
  • Support for Sesame
• ASP.Net Integration
  • Added a NativeSPARQLHandler which allows you to set up an endpoint on any of the supported backing stores

You can go ahead and Download dotNetRDF to get the latest version of the library of Download dotNetRDF Source if you want the latest source code.

We'll shortly be updating the API to indicate changes and new features in the User Guide

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Just to let people know I'm pretty close to releasing the next version of dotNetRDF. This fixes a whole range of bugs particularly in the SPARQL engine and adds a lot of new features which include some of the following:

• Support for more backing Stores with querying over any of them using their own SPARQL engines
  • 4store
  • AllegroGraph
  • Sesame
• SPARQL Improvements
  • Support for some parts of the SPARQL 1.1 Working Draft specification
  • Performance optimisations
• Support for additional concrete syntaxes
  • NQuads
  • TriX
• Experimental inference support
  • RDFS class hierarchy reasoner
  • SKOS concept hierarchy reasoner

Release is probably going to be next Friday/Monday depending on whether final testing shows up any bugs and other work commitments.

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One of the main things I've been working towards for the next release of the Library is to support additional backing Stores so people have the choice of using Stores that suit their needs and to allow them to build .Net applications which use their existing Stores. In the existing release I support Talis and Virtuoso which are two very different Stores but they are only 2 from a veritable plethora of available software. One of my aims is to try and support popular technologies and so I have implemented support for the following Stores in the latest builds of the library:

1. 4store is an open source store from Garlik which scales into the billion Triples range, supports named Graphs and has a RESTful HTTP protocol available.
2. Sesame 2.0 HTTP Protocol is a RESTful HTTP protocol for communicating with Sesame 2.0 servers but it is also supported by other Triplestores. Adding support for this means Sesame and any other servers compliant with the protocol can be used.
3. AllegroGraph is a another massively scalable Triplestore from Franz Inc which uses a RESTful protocol conforming to the Sesame 2.0 specification with some extensions. Currently support does not use any of these it is just aware of the differing URI structure in particular the notion of having catalogs of repositories (Sesame protocol only has repositories).

I'm also adding support for all of these to the new NativeSPARQLHandler class which allows you to create an ASP.Net SPARQL endpoint which uses any of the supported Native stores to execute queries. There is also a new NativeTripleStore class being added which can be used to query against the backing Store in code.

Hopefully people will find this expanded storage support useful when the new release comes out.

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I thought I would write a quick post to update people on recent work I have been doing in improving dotNetRDF for the next release. One of the major changes in the new version is a new internal storage mechanism for Triples which now uses a full blown Hash Table which makes storing colliding Triples much easier. Hash Tables are also used for creating a number of indexes to significantly improve the speed of some types of lookups. This change comes with a minor performance impact on loading times and increased storage requirements but the benefits are immediately clear in our benchmarking, in particular this change gives much better SPARQL performance and a more graceful scaling of performance with number of Triples (appears linear rather than exponential).

One of the main things I've been working on is implementing various aspects of the SPARQL 1.1 working draft which seem most stable into the SPARQL Engine. So far I have implemented Project Expressions, Aggregates along with simple GROUP BY and HAVING clauses.

In addition to this I have now added support for 4store into the library which makes 3 different native Stores that can be used out of the box - Talis Platform, Virtuoso Universal Server and 4store.

At the moment it looks like I will probably do the 0.1.2 Alpha Release at the end of November depending on other time constraints.

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