CORNER: A Completeness Reasoner for SPARQL Queries
over RDF Data Sources1
Fariz Darari
Radityo Eko Prasojo
Werner Nutt
EPC...
Intro
Fariz Darari (EPCL Workshop 2014) CORNER 2 / 13
Intro
Completeness
statement about the
IMDB data source
Quentin Tarantino
was the character
Mr. Brown
……………
……………
……………
ht...
Intro
Fariz Darari (EPCL Workshop 2014) CORNER 4 / 13
Motivations
Fariz Darari (EPCL Workshop 2014) CORNER 5 / 13
Motivations
Fariz Darari (EPCL Workshop 2014) CORNER 6 / 13
Motivations
Darari et al.2
developed a logical framework for
completeness reasoning techniques on the Semantic Web
The fra...
CORNER
We built an implementation of the framework, called
CORNER (short for Completeness Reasoner :)
A Web-based demo can...
CORNER: Functionalities
Users can specify SPARQL basic graph pattern (BGP)
queries, whose completeness is to be checked.
U...
CORNER: Screenshot
Fariz Darari (EPCL Workshop 2014) CORNER 10 / 13
CORNER: Architecture
Fariz Darari (EPCL Workshop 2014) CORNER 11 / 13
CORNER: Reasoning Steps
From the query Q, CORNER generates an initial graph Gi
Q
representing the information needed for a...
CORNER: Demo
Link to Demo Video on Youtube
http://bit.ly/cornerDemo
Link to CORNER
http://corner.inf.unibz.it/
Fariz Darar...
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CORNER: A Completeness Reasoner for SPARQL Queries over RDF Data Sources

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With the increased availability of data on the Semantic Web,
the question whether data sources offer data of appropriate quality
for a given purpose becomes an issue.
With CORNER, we specifically address the data quality aspect of completeness.
We demonstrate a formal way to state for which topics
an RDF source is complete and how to use such statements to automatically
analyze whether a given query will return a complete answer
over a source.
CORNER supports SPARQL BGP queries and can take RDFS ontologies into
account in its analysis. If a query can only be answered completely by
a combination of sources, CORNER rewrites the original query into
one with SPARQL SERVICE calls, which assigns each query part to
a suitable source, and executes it over those sources.
CORNER builds upon previous work by Darari et al.
and is implemented using standard Semantic Web frameworks.

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CORNER: A Completeness Reasoner for SPARQL Queries over RDF Data Sources

  1. 1. CORNER: A Completeness Reasoner for SPARQL Queries over RDF Data Sources1 Fariz Darari Radityo Eko Prasojo Werner Nutt EPCL Workshop 2014, Dresden 1 to be demonstrated also at ESWC 2014 Fariz Darari (EPCL Workshop 2014) CORNER 1 / 13
  2. 2. Intro Fariz Darari (EPCL Workshop 2014) CORNER 2 / 13
  3. 3. Intro Completeness statement about the IMDB data source Quentin Tarantino was the character Mr. Brown …………… …………… …………… http://www.imdb.com/title/tt0105236/fullcredits?ref_=tt_ov_st_sm#cast Fariz Darari (EPCL Workshop 2014) CORNER 3 / 13
  4. 4. Intro Fariz Darari (EPCL Workshop 2014) CORNER 4 / 13
  5. 5. Motivations Fariz Darari (EPCL Workshop 2014) CORNER 5 / 13
  6. 6. Motivations Fariz Darari (EPCL Workshop 2014) CORNER 6 / 13
  7. 7. Motivations Darari et al.2 developed a logical framework for completeness reasoning techniques on the Semantic Web The framework enables creation of descriptions as to which parts of a data source are complete, called completeness statements Checks whether a query returns a complete result, called query completeness checks, are then possible However, implementation is still missing 2 Fariz Darari, Werner Nutt, Giuseppe Pirró, Simon Razniewski: Completeness Statements about RDF Data Sources and Their Use for Query Answering. ISWC 2013 Fariz Darari (EPCL Workshop 2014) CORNER 7 / 13
  8. 8. CORNER We built an implementation of the framework, called CORNER (short for Completeness Reasoner :) A Web-based demo can be accessed at http://corner.inf.unibz.it/ Implementation reused the Apache Jena (Semantic Web library) and Google Web Toolkit (User Interface library) Fariz Darari (EPCL Workshop 2014) CORNER 8 / 13
  9. 9. CORNER: Functionalities Users can specify SPARQL basic graph pattern (BGP) queries, whose completeness is to be checked. Users can specify completeness statements of a specific data source. There are also the options to upload and download completeness statements in CORNER. Users can specify RDFS ontologies for use in completeness reasoning. If a query is analyzed to be complete, CORNER can rewrite the query into an executable, federated query whose answers are complete. From completeness reasoning results, users may see the debugging information to learn why the query can be answered completely. Fariz Darari (EPCL Workshop 2014) CORNER 9 / 13
  10. 10. CORNER: Screenshot Fariz Darari (EPCL Workshop 2014) CORNER 10 / 13
  11. 11. CORNER: Architecture Fariz Darari (EPCL Workshop 2014) CORNER 11 / 13
  12. 12. CORNER: Reasoning Steps From the query Q, CORNER generates an initial graph Gi Q representing the information needed for answering the query Every completeness statement C is translated into a SPARQL CONSTRUCT query QC Application of all the queries QC to the graph Gi Q results in a subgraph Ga Q of Gi Q, representing parts of the query for which data are complete By evaluating Q over Ga Q, CORNER tests whether the complete data are sufficient to answer Q If Q can be answered completely, based on the data sources information of the completeness statements that contribute to generate Ga Q, CORNER distributes the query parts of Q to their suitable, complete sources Fariz Darari (EPCL Workshop 2014) CORNER 12 / 13
  13. 13. CORNER: Demo Link to Demo Video on Youtube http://bit.ly/cornerDemo Link to CORNER http://corner.inf.unibz.it/ Fariz Darari (EPCL Workshop 2014) CORNER 13 / 13
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