Ontology-Based Integration of XML Data

The Semantic Web—ISWC …, 2002

Proceedings. International Database Engineering and Applications Symposium, 2004. IDEAS '04., 2004

XML is becoming the standard for data interchange on the web. However, XML and its schema languages do not express semantics but rather structure, such as nesting information. Therefore, semantically equivalent documents often present different document structures. In this paper, we provide an ontology-based framework that aims to make two XML documents interoperate at the semantic level while retaining their nesting structure. In our global-asview approach, we generate an RDF ontology for each of the participating XML documents, which preserves the nesting structure of the document. An RDF global ontology is the result of merging the individual ontologies. The global ontology unifies the query access and establishes semantic connections among the underlying individual databases. We consider two types of queries: those that are posed on the global ontology and those that are posed on any of the XML documents, in a P2P fashion. The former type is processed using query translation from an RDF query to an XML query. The latter type entails bidirectional query processing: the translation from an XML query to an RDF query followed by the translation from an RDF query to an XML query. To ensure the correctness of the answer to the query in the latter case, we introduce the concept of reversibility of the query translation.

Journal of Digital Information Management, 2005

In this paper we present an ontology-based method for formalizing the implicit semantic and we suggest mechanisms to semantically integrate XML schemas and documents as well. After a survey of database interoperability, we present our semantic integration approach by explaining the nature of ontology. The article then presents our integration method for XML data and schemas using a generic ontology.

2001

XML raises as the standard for semistructured data representation and data exchange in the Web. In this context, data integration mechanisms are required to provide an unified view of semantically related information of a same domain. In this paper, a bottom-up integration process is proposed to solve such problem. In this approach, an ontology is generated from the semantic integration of conceptual schemata derived from DTDs. The process is semi-automatic taking into account the intervention of an human expert to provide semantic adjustments. The resulting ontology is an unified vocabulary for semistructured concepts presented in several XML sources; keeps mapping information to DTD elements and attributes; and acts as a global schema for user queries. The overall integration process is briefly presented through examples.

2003

This paper presents a novel approach for the integration of a set of XML Schemas. The proposed approach is specialized for XML, is almost automatic, semantic and "light". As a further, original, peculiarity, it is parametric w.r.t. a "severity" level against which the integration task is performed. The paper describes the approach in all details, illustrates various theoretical results, presents the experiments we have performed for testing it and, finally, compares it with various related approaches already proposed in the literature.

2004

Reconciling of knowledge from multiple heterogeneous data sources has been a major focus of database research for more than a decade.As a standard for exchanging business data on the WWW, XML should provide the ability of expressing data and semantics among them. Since most of application data are stored in relational databases due to its popularity and rich development experiences over it.Therefore, how to provide a proper mapping approach from relational model to XML model becomes the major research problem in the field of current information exchanging, sharing and integration..The model needs to be integrated and at the same time maintain the semantic knowledge among the data. The aim of this paper is to provide an overview for XML based data integration on semantic knowledge.At the end of the paper, we review some methodologies from existing literature.

Lecture Notes in Computer Science, 2002

We define an object-oriented data model called XSDM (XML Schema Data Model) and present a graphical representation of XML Schema integration. The three layers included are, namely, pre-integration, comparison and integration. During pre-integration, the schema present in XML Schema notation is read and is converted into the XSDM notation. During the comparison phase of integration, correspondences as well as conflicts between elements are identified. During the integration phase, conflict resolution, restructuring and merging of the initial schemas take place to obtain the global schema.

2001

The paper describes a prototype tool, named DIXSE, which supports the integration of XML Document Type Definitions (DTDs) into a common conceptual schema. The mapping from each individual DTD into the common schema is used to automatically generate wrappers for XML documents, which conform to a given DTD. These wrappers are used to populate the common conceptual schema thereby achieving data integration for XML documents.

Lecture Notes in Computer Science, 2003

Various XML instances from different data sources can model the same object of the real world. Query processing or view definition over these sources demands instance integration. In this context, integration means to identify which data instances represent the same object of the real world, as well as to solve ambiguities of representation of this object. The entity identification problem in XML is more complex than in structured databases. XML data, as originally considered, necessarily do not have the identification notion of primary key or object identifier. Thus, it is necessary the adoption of a mechanism that identifies the instances at the moment of data integration. This paper presents a proposal for identifiers attribution to XML instances, based on the use of Skolem functions and XPath recommendation, as proposed by W3C. Integration of XML Data 75 2.1 State of the Art Universal Key This is the simplest method for data integration. It is based on the existence of a common key between the instances to be integrated [2, 14, 16, 17, 23]. However, this approach is restricted, since the sources not always have a common key, as XML data. Key Equivalence Specified by the User This approach requires that the user specifies equivalence between the instances, for example, using a mapping table of the local identifiers from each source to the global identifiers in the integrated system. This technique is used in [1, 18, 20]. The disadvantage of this technique is that the mapping table can be considerable and present difficult maintenance, handled by the database administrator, not in a automatic way.

Lecture Notes in Computer Science, 2005

This paper presents a detailed integration process for XML schemata called BInXS. BInXS adopts a global-as-view integration approach that builds a global schema from a set of heterogeneous XML schemata related to a same application domain. This bottom-up approach maps all element and attribute definitions in XML schemata to correspondent concepts at the global schema, allowing access to all data available at the XML sources. The integration process is semiautomatically performed over conceptual representations of the XML schemata, which provides a better understanding of the semantics of the XML data to be unified. A conceptual schema is generated by a set of conversion rules that are applied to a schema definition for XML data. Once this conceptual schema is the result of a meticulous analysis of the XML logical model, it is able to abstract the particularities of semistructured and XML data, like elements with mixed contents and elements with alternative representations. Therefore, the further unification of such conceptual schemata implicitly deals with structural conflicts inherent to semistructured and XML data. In addition, BInXS supports a mapping strategy based on XPath expressions in order to maintain correspondences among global concepts and data at the XML sources. 5 Figure 2 (b) is a logical abstraction of a schema defined through a DTD (Document Type Definition) or an XSD (XML Schema Definition) [5]