Section: Software and Platforms

Alaska

Participants : Bruno Paiva Lima Da Silva, Jean-François Baget, Madalina Croitoru.

Alaska (http://alaska.bplsilva.com/ ) is a java library dedicated to the storage and querying of large knowledge bases. It intends to be the foundation layer of our OBDA (Ontology Based Data Access) software developments. It has been built, first as part of a master thesis, and now of Bruno Paiva Lima da Silva' PhD (that will be defended in Jan. 2014).

In Alaska, facts and queries are defined via a generic interface that favors a logical view of these objects. Implementations of this interface allow for the storage of facts w.r.t. different storage paradigms and systems (e.g., relational databases MySQL and Sqlite; triple stores Sesame and graph databases Neo4J, DEX, HyperGraphDB and OrientDB). For the time being, we can store ${10}^7$ to ${10}^8$ atoms. In the same way, logical queries can be evaluated through different methods, be it the native querying mechanism of the considered database (e.g. SPARQL or SQL), or specifically designed algorithms (from a simple backtrack to a full constraint solver based upon Choco http://www.emn.fr/z-info/choco-solver/ for hard problem instances). Note that all these methods provide the same answer set to queries.

This library already allows for testing our OBDA algorithms on large instances. The ADT Quasar (that will start in March 2014) will involve the integration of Alaska with other tools developped in the team (see also Section  5.4 ), and its improvement from a research library to a distributable tool.