Mediation of XML Data through Entity Relationship Models

This paper describes an approach for the querying of heterogeneous XML resources using an ontology-based mediator. Here an ontology is an Entity-Relationship schema defined independently of the schemas of the data sources. The sources are described to the mediator by means of mapping rules as in the Local-As-View approach to data integration. User queries are conjunctive queries formulated in terms of the ontology, and answers to these queries are obtained by rewriting them to XQuery expressions and evaluating these on the data sources. A formal semantics for queries is defined by interpreting XML sources into ER models. As there can be many such interpretations, a certain answer to a query is one which is true in all of them. We describe the rewriting algorithm and we show its completeness and correctness with respect to the given semantics. We also give an algorithm for producing a canonical model of the ontology and the interpreted data sources. It is shown that the certain answers can also be obtained by evaluating the query to just this one model.

[1]  Dennis McLeod,et al.  A federated architecture for information management , 1985, TOIS.

[2]  Sophie Cluet,et al.  Designing OQL: Allowing Objects to be Queried , 1998, Inf. Syst..

[3]  Alberto O. Mendelzon,et al.  Tableau Techniques for Querying Information Sources through Global Schemas , 1999, ICDT.

[4]  Nicolás Marín,et al.  Review of Data on the Web: from relational to semistructured data and XML by Serge Abiteboul, Peter Buneman, and Dan Suciu. Morgan Kaufmann 1999. , 2003, SGMD.

[5]  Diego Calvanese,et al.  View-Based Query Answering and Query Containment over Semistructured Data , 2001, DBPL.

[6]  Alex Thomo,et al.  New Rewritings and Optimizations for Regular Path Queries , 2003, ICDT.

[7]  Dan Suciu,et al.  Data on the Web: From Relations to Semistructured Data and XML , 1999 .

[8]  Gio Wiederhold,et al.  Intelligent integration of information , 1993, SIGMOD Conference.

[9]  Michael R. Genesereth,et al.  Answering recursive queries using views , 1997, PODS '97.

[10]  Alon Y. Halevy,et al.  Answering queries using views: A survey , 2001, The VLDB Journal.

[11]  Abel,et al.  A formal semantics of patterns in XSLT , 2000 .

[12]  Serge Abiteboul,et al.  Foundations of Databases , 1994 .

[13]  Catriel Beeri,et al.  Ontology-Based Integration of XML Web Resources , 2002, SEMWEB.

[14]  Diego Calvanese,et al.  Rewriting of regular expressions and regular path queries , 1999, PODS '99.

[15]  Joann J. Ordille,et al.  Querying Heterogeneous Information Sources Using Source Descriptions , 1996, VLDB.

[16]  Nick Roussopoulos,et al.  Interoperability of multiple autonomous databases , 1990, CSUR.

[17]  Todd D. Millstein,et al.  Navigational Plans For Data Integration , 1999, AAAI/IAAI.

[18]  Laurian M. Chirica,et al.  The entity-relationship model: toward a unified view of data , 1975, SIGF.

[19]  Wenfei Fan,et al.  Keys for XML , 2001, WWW '01.

[20]  Prasenjit Mitra.  An algorithm for answering queries efficiently using views , 2001, ADC.

[21]  Catriel Beeri,et al.  Querying XML Sources Using an Ontology-Based Mediator , 2002, CoopIS/DOA/ODBASE.

[22]  Steven J. DeRose,et al.  XML Path Language (XPath) Version 1.0 , 1999 .

[23]  Arvind Malhotra,et al.  Xml schema part 2: datatypes , 1999 .

[24]  Maurizio Lenzerini,et al.  Data integration: a theoretical perspective , 2002, PODS.

[25]  Jennifer Widom,et al.  Research problems in data warehousing , 1995, CIKM '95.

[26]  Claude Delobel,et al.  A Uniform Approach for Querying Large Tree-structured Data through a Mediated Schema , 2001 .

[27]  Ronald Fagin,et al.  Data exchange: semantics and query answering , 2003, Theor. Comput. Sci..

[28]  HalevyAlon,et al.  MiniCon: A scalable algorithm for answering queries using views , 2001, VLDB 2001.

[29]  Catriel Beeri,et al.  STYX: Connecting the XML Web to the World of Semantics , 2002, EDBT.

[30]  Alon Y. Halevy,et al.  MiniCon: A scalable algorithm for answering queries using views , 2000, The VLDB Journal.