This maintenance release includes Sesame 2.4.2, which fixes several important bugs in SPARQL 1.1 Query support:
Also included are some updates to OWLIM-SE:
- Unexpected binding returned in a Sparql query with union within an optional expression
- FILTER in OPTIONAL patterns returns incorrect results
- Aggregate SPARQL query fails with IndexOutOfBoundsException
- Default and named graphs set in a SPARQL query are ignored by the Jena connector
- OWLIM Replication Cluster has been renamed to OWLIM-Enterprise and is distributed separately from OWLIM-SE. This new name better identifies this software component as the flagship product of the OWLIM family suitable for mission critical applications.
- Easy to deploy WAR files: The distribution now includes openrdf-sesame and openrdf-workbench Web applications pre-configured with OWLIM and ready to deploy. This makes installing OWLIM as a server and creating/administrating OWLIM repositories trivially simple. The WAR files can be found in the sesame_owlim directory of the distribution ZIP file. See 'easy install' in the installation section.
- SPARQL 1.1 Query: Ontotext has invested significant development resources in the Sesame project in order to bring SPARQL 1.1 support to all editions of OWLIM. Since OWLIM-Enterprise is a distributed architecture based on OWLIM-SE, OWLIM-Enterprise also includes SPARQL 1.1 Query, but without federation support for the moment. SPARQL 1.1 Update support will be included in the next release. The new features include:
- Expressions in the SELECT clause
- Property Paths
- A short form for CONSTRUCT
- An expanded set of functions and operators
- The SPARQL 1.1 specification has not yet become a W3C recommendation and continues to evolve. The following known issues apply to this release of OWLIM and Sesame:
- fn:concat is not supported. This was added to the working draft in May, just after the Sesame 2.4.0 release was finalised. It will likely be included in the next Sesame/OWLIM release.
- Empty IN() and NOT IN() clauses will cause an exception - will be fixed in the next release.
- Using the aggregate function SUM() will cause an exception if the there are no bindings over which to do the summation - will be fixed in the next release.
- Federation is not yet supported. This will be implemented in a later version of Sesame and OWLIM later this year.
- There are some problems with complex expressions in the SELECT clause. This should be fixed in the next release of Sesame/OWLIM.
This release includes many bug fixes, several new features and updates:
- Write-only worker node: When worker nodes are added to the cluster via the JMX interface, they can be specified as being 'write-only'. These nodes will be kept in synch with the rest of the cluster, but will not take part in answering cluster queries. The motivation for this feature is to have one or more worker nodes available for batch processing of queries that do not affect the overall query performance of the cluster.
- Remote notifications: A new mechanism to complement the existing high-performance 'in-process' notification mechanism. This new mechanism allows clients to subscribe for the given statement patterns to OWLIM Replication Cluster master nodes.
- Online documentation: As well as the PDF format user guides included in the OWLIM distribution zip files, the latest documentation for all editions of OWLIM is now available online.
- Replication cluster introduced in this version of OWLIM: brings resilience, failover and horizontally scalable parallel query processing. A master node component is included that can manage a cluster of worker nodes (standard BigOWLIM instances) to synchronise updates, cater for node failure, dynamically add/remove worker nodes and distributed query requests. Such a setup allows for massive concurrent query performance where the number of queries processed per second scales almost linearly with the number of worker nodes