What is Mastro Studio?
Mastro Studio is a web-based platform for data management through the OBDA paradigm. Mastro Studio provides an environment for documentation and inspection of the components of an OBDA specification (ontology, mappings, and data sources), and an interface for the ontology reasoning services offered by Mastro, the OBDA reasoner at its core. An example of these services is a SPARQL endpoint for querying data sources through the ontology.
Mastro Studio's services
Inspection of OBDA Components
Mastro Studio offers support for the inspection of all three of the components of the OBDA architecture: the ontology, the mappings, and the data sources.
Ontologies in Mastro Studio are specified through Graphol, so they are accessible to both expert and non-expert users. Mastro Studio allows to navigate between the ontology diagrams and the documentation of the ontology predicates, which is presented in a wiki-like format: each predicate page contains a rich description of the meaning of each predicate, and lists its ontology and mapping assertions.
Users can also see the details of every mapping assertion defined for the ontology predicates, and inspect the tables in the database underlying the ontology.
Mastro Studio allows to exploit all reasoning services over the ontology that are offered by the Mastro reasoner. These services can be classified into intensional and extensional reasoning services.
Intentional reasoning services deal with reasoning over the ontology (independently of the mappings), and provide the ability to compute all the formulas that are logically implied by the axioms in the ontology.
Extensional reasoning services exploit the mappings and the data sources, and allow users to invoke query answering, through Mastro Studio's SPARQL end-point, and check satisfiability and data quality, which highlight anomalies in the data (or the ontology) by comparing the data at the sources with the axioms in the ontology.
Technical specs of Mastro Studio's OBDA components
The ontology is a DL-Lite ontology specified through OWL 2 axioms.
The mappings that define the relationship between the sources and the ontology are expressed through a set of GAV assertions, which associate elements of the ontology to queries over the underlying database.
- Data Sources
The data sources are managed by a Java-based RDBMS.
Architecture of the System
Mastro Studio's components in detail
The Ontology Inspection component allows the user to navigate the Graphol ontology, switching from the diagrams to the wiki pages describing each element in the ontology, and to inspect the axioms, rendered in Functional Syntax, of the OWL 2 translation of the ontology
The Mapping Inspection component shows the head and body of each mapping assertion in the OBDA specification. The head of the mapping is an element of the ontology, while the body is an SQL query, or possibly a conjunction of queries, over the data sources.
The Data Source Inspection component allows the user to visualize the structure of the source relations and to pose direct SQL queries over it.
The Intentional Reasoning component allows the user to visualize all the subsumptions, for each element of the ontology, that are logically inferred by the ontology.
The Query Answering environment allows to specify queries in SPARQL syntax over the ontology, and to visualize the answers returned by the reasoner. The component also allows the visualization of each step of the rewriting procedure needed for answering queries posed over the OBDA specification.