Integration of XML Schemas at various “severity” levels

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.

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.

Data & Knowledge Engineering, 2008

The availability of large amounts of heterogeneous distributed web data necessitates the integration of XML data from multiple XML sources for many reasons. For example, currently, there are many e-commerce companies, which offer similar products but use different XML schemas with possibly different ontologies. When any two such companies merge, or make an effort to service customers in cooperation, there is a need for an integrated schema and query mechanism for the interoperability of applications. In applications like comparison-shopping, there is a need for an illusionary centralized homogeneous information system. In this paper, we propose XML Schema integration and querying methodology. We define an object-oriented data model called XSDM (XML Schema Data Model) and present a graphical representation of XML Schema for the purpose of schema integration. We use a three-layered architecture for XML Schema integration. The three layers included are namely pre-integration, comparison and integration. The three layers can conceptually be regarded as three phases of the integration process. During pre-integration, the schemas present in XML Schema notation are read and 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 takes place to obtain the global schema. We define integration policies for integrating element definitions as well as their datatypes and attributes. An integrated global schema forms the basis for querying a set of local XML documents. We discuss various strategies for rewriting the global query over the global schema into the sub-queries over local schemas. Their respective local schemas validate the subqueries over the local XML documents. This requires the identification and use of mapping rules and relationships between the local schemas.

Abstract. Modern information systems may exploit numerous XML formats for communication. Each message may have its own XML format for data representation which causes problems with integration and evolution of their schemas. Manual integration and management of evolution of the XML formats may be very hard. We tackled this problem in our previous work, however, for simplicity reasons, we omitted the possibility of exploiting reusable schema parts.

Label Streams, Semantics Utilization and Data Query Technologies

In XML Data Integration, data/metadata merging and query processing are indispensable. Specifically, merging integrates multiple disparate (heterogeneous and autonomous) input data sources together for further usage, while query processing is one main reason why the data need to be integrated in the first place. Besides, when supported with appropriate user feedback techniques, queries can also provide contexts in which conflicts among the input sources can be interpreted and resolved. The flexibility of XML structure provides opportunities for alleviating some of the difficulties that other less flexible data types face in the presence of uncertainty; yet, this flexibility also introduces new challenges in merging multiple sources and query processing over integrated data. In this chapter, the authors discuss two alternative ways XML data/schema can be integrated: conflict-eliminating (where the result is cleaned from any conflicts that the different sources might have with each ot...

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, 2012

Querying XML databases and their integration is an emerging area in applications related to database management systems. XML documents having similar data may differ in their organization. Hence a single query may not produce uniform results in all the documents. Different queries have to be generated for each of these hierarchies. To avoid this overhead, it is proposed to restructure and integrate different schemas by transforming all the XML schemas to a unique schema. We propose an algorithm to generate a unified query to extract results from this unique schema. Our work is demonstrated using an application of Primary Health Care (PHC) data maintenance system.

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.

J. Univers. Comput. Sci., 2004

In this paper we propose X-Global, a novel, almost automatic and semantic system for integrating a set of XML sources. X-Global is parametric w.r.t. the flexibility level against which the integration task is performed; indeed, it can operate on rigid contexts, when two concepts are merged only if they have exactly the same meaning, as well as on flexible and informal situations, when two concepts are merged if they have close, even if not exactly identical, meanings. In this paper we describe the system in all details, illustrate various theoretical results as well as several experiments we have carried out for verifying its performance. Finally, we examine related literature and point out similarities and differences between X-Global and several other approaches already proposed in the past.

In this paper we propose a novel, almost automatic and semantic approach for integrating a set of XML sources. The approach is parametric w.r.t, the flexibility degree against which the integration task is performed," indeed, it can operate on rigid contexts, when two concepts are merged only if they have exactly the same meaning, as well as on flexible and informal situations, when two concepts are merged if they have close, even if not exactly identical, meanings. This paper describes the approach in all details, illustrates various theoretical results, examines the related literature and points out similarities and differences between the proposed approach and the existing ones. 0-7803-7983-7/03/$17.00 ©2003 IEEE An x-component is characterized by its name, its type, its cardinality and, if it is an element, by its content specification. These last three features are better specified by the following definitions.