A new architecture for dynamic e-business database interoperability

There have been many approaches of data sharing in e-businesses, attempting at mapping each field at the source to its corresponding field at the target. These approaches eliminate the need for deriving the global schema and hence eliminate a substantial overhead. But, the approaches work out well only when both the source and the target databases have approximately the same content. Moreover, if some concepts of source do not have the counterpart fields in the target then the mapping will lose the concepts. This problem will be further aggregated by the mapping compositions and the large size of the databases. In this paper, we propose a framework to alleviate the interoperability problem

Querying XML Data with SPARQL

Abstract. SPARQL is today the standard access language for Semantic Web data. In the recent years XML databases have also acquired industrial impor-tance due to the widespread applicability of XML in the Web. In this paper we present a framework that bridges the heterogeneity gap and creates an interop-erable environment where SPARQL queries are used to access XML databases. Our approach assumes that fairly generic mappings between ontology con-structs and XML Schema constructs have been automatically derived or manu-ally specified. The mappings are used to automatically translate SPARQL que-ries to semantically equivalent XQuery queries which are used to access the XML databases. We present the algorithms and the implementation of SPARQL2XQuery framework, which is used for answering SPARQL queries over XML databases

Ontology-Based RDF Integration of Heterogeneous Data

The proliferation of heterogeneous data sources in many application contexts brings an urgent need for expressive and efficient data integration mechanisms. There are strong advantages to using RDF graphs as the integration format: being schemaless, they allow for flexible integration of data from all sources; RDF graphs can be interpreted with the help of an ontology, describing application semantics; last but not least, RDF enables joint querying of the data and the ontology. To address this need, we introduce the novel class of RDF Integration Systems (RIS), going beyond the state of the art in the expressive power, that is, in the ability to expose, integrate and flexibly query data from heterogeneous sources through GLAV (global-local-as-view) mappings. Our second contribution is a set of query answering strategies, two combining existing techniques and three others based on an innovative integration of view-based rewriting; our experiments show that the latter bring strong performance advantages

Global schema generation and query rewriting XML integration

Master'sMASTER OF SCIENC

Level-based indexing for optimising XML queries

Many of the problems with native XML databases relate to query performance and subsequently, it can be difficult to convince traditional database users of the benefits of using semi- or unstructured databases. In particular, the ongoing development of the XQuery language requires that performance related issues are resolved. Presently, there still lacks an index structure providing efficient support for both navigational and structural queries and the traditional data-centric and content queries. This thesis presents a new extended index structure based on the preorder traversal rank and the level (or depth) rank of each node in a document tree. The extended index fully supports the navigation of all XPath axes while efficiently supporting data-centric queries. The ability to start path traversals from arbitrary nodes in a document tree also enables the extended index to support the evaluation of path traversals embedded in XQuery expressions. Furthermore, an encoding technique for this extended index structure is presented, whereby properties of a level ranking may be exploited to provide efficient and optimised path traversals and in certain cases, optimal solutions to path traversals

Querying XML Sources Using an Ontology-Based Mediator

Abstract. In this paper we propose a mediator architecture for the querying and integration of Web-accessible XML data sources. Our contributions are (i) the definition of a simple but expressive mapping language, following the local as view approach and describing XML resources as local views of some global schema, and (ii) efficient algorithms for rewriting user queries according to existing source descriptions. The approach has been validated by the ¦¨§�©�� prototype.