KroRdfobda
The objective of this project is to explore the use of the DL-LiteA rewriting based technique for query answering over ontologies with mappings in creating flexible and fast RDF repositories and SPARQL endpoints. In this project you will learn the relationship between RDFS reasoning and DL-LiteA reasoning. You will also get hands on experience in several tools that are used in the Semantic Web such as Jena and the OWLAPI.
You will start this project by performing an analysis of the relationship between RDFS [see] DL-LiteA reasoning, specifically, on answering SPARQL queries and Union of Conjunctive Queries (UCQs). Also, you will present a proposal of an RDF repository with mappings to relational databases, that is, an RDF repository that doesn't hold data but only the schema and a set of mappings that define a 'virtual triple set'. Based on this analysis, you will create a proposal on reusing existing software (i.e., the QuontoOWLAPI reasoner and the OBDALib) to create a SPARQL endpoint for RDF repositories with mappings to relational databases. Tasks involved in the process include the translation of RDF ontologies into OWL ontologies for the Quonto reasoner, the translation of SPARQL queries into conjunctive queries, and the transformation of answer tuples into RDF triples. The proposal should include the proposal for the architecture of the system, that is, each of the modules involved, their relationship between them and their functionality.
Finally, you will provide a small demo using simple webpage were one can query the endpoint running a simple scenario running over your system.
In the creation of this project, there will be several task that will be much easier if you reuse existing open source libraries (apart from Quonto and the OBDALib). Specifically it is recommended that you use the following:
- Jetty. For providing the HTTP access required by SPARQL endpoints.
- OWLAPI. For creating OWL ontologies (the input for Quonto and the OBDALib)
- Jena and ARQ. For parsing SPARQL queries.
Correctness of the implementation will be performed with a set of simple test cases (RDFS ontology, database, mappings and queries) that the system should evaluate correctly. The files required to carry out these comparisons will be provided at a later time.
The API of the project should be properly modularized with components that handle each of the task involved in the system as independent operations. Each of these modules should be properly documented using JavaDoc and inline comments.
The final package of the project should include
- A executable JAR that allows to start the application
- Means to build and pack the project from the sources. For this task, and to facilitate the management and definition of dependencies (e.g., Jars from libraries used for the project such as the OWLAPI, Jetty, Jena) it is recommended that the project is setup to use Maven 2 since it will much easier to setup. A quick start guide for Maven 2 can be found here. If the project is developed using Eclipse it is recommended the use of the m2Eclipse plugin to facilitate development.
- First deliverable. Document describing the architecture of the system. The functionality of each of the modules of the system as well as the concrete implementation choices for each of them.
- Second deliverable. An initial overview of the status of the implementation detailing open issues.
- Third and final deliverable. A final document including the updated architecture and system proposal to reflect the final stage of the development. A simple user manual for the application. The software package described above.
- 1. Foundations of Semantic Web Technologies. Pascal Hitzler, Markus Krötzsch and Sebastian Rudolph. CRC Press. 2009.
- 2. Programming the Semantic Web, 1st Edition. Toby Segara, Colin Evans and Jamie Taylog. O;Reilly Media Inc. 2009. Available in FUB's Safari ebook repository here
- Tractable reasoning and efficient query answering in description logics: The DL-Lite family. Diego Calvanese, Giuseppe De Giacomo, Domenico Lembo, Maurizio Lenzerini, and Riccardo Rosati. J. of Automated Reasoning, 39(3):385-429, 2007. pdf
- Ontologies and databases: The DL-Lite approach. Diego Calvanese, Giuseppe De Giacomo, Domenico Lembo, Maurizio Lenzerini, Antonella Poggi, Mariano Rodriguez-Muro, and Riccardo Rosati. In Sergio Tessaris and Enrico Franconi, editors, Semantic Technologies for Informations Systems - 5th Int. Reasoning Web Summer School (RW 2009), volume 5689 of Lecture Notes in Computer Science, pages 255-356. Springer, 2009.
- Linking data to ontologies Antonella Poggi, Domenico Lembo, Diego Calvanese, Giuseppe De Giacomo, Maurizio Lenzerini, and Riccardo Rosati. J. on Data Semantics, X:133-173, 2008. pdf