Academic journal article Journal of Digital Information Management

Application-Level Solution for Data Integration in Ubiquitous Computing Environment

Academic journal article Journal of Digital Information Management

Application-Level Solution for Data Integration in Ubiquitous Computing Environment

Article excerpt

1. Introduction

Recent technological trends in electronics have resulted in a change in people's lifestyle, whereby mobile devices such as mobile phones, PDA's, GPS devices, etc. and sensor devices such as temperature, humidity, location, etc. have become an integral part of everyday life. This trend, together with the advancement in wireless communication technology, has raised users' expectations about the accessibility of services in Ubiquitous Computing environments [16] [19] [22]. This has raised challenges for service representation, service discovery and query answer in a dynamic environment, where services encapsulates mobile data and/or sensor data (call them Ubiquitous data). A Ubiquitous Computing environment, like the one that Ambient Intelligence [7] promotes, is a technologically augmented multi-sensor environment capable of capturing the context and activities of the users in order to respond to their needs. One main objective of such an environment is to provide ambient data services to users based on their needs in different context. However, how to encapsulate these mobile data into data services and how to provide these services to the user given the concrete application remain challenging issues.

The Semantic Web [1] aims to provide a common semantic framework allowing data to be shared and reused across application and community boundaries. It is based on the RDF(Resource Description Framework) framework (1) and OWL(Web Ontology Language) language (2), which is proposed and standardized by W3C organization to represent web information in a flexible, but meaningful way so that data can be exchanged and integrated without loss of semantics. However, Most of existing data in a ubiquitous computing environment is locally stored in mobile devices or sink nodes. Therefore, for semantic web to be really useful and successful in a ubiquitous computing environment, great efforts are required to offer methods to support integration and share of heterogeneous Ubiquitous data sets using ontology model [11]. A plurality of solutions have thus far been prescribed to ease the burdensome of the issue [17] [9] [13]. Chief among them is the semantic web service [6] [15] technologies which have been adopted in improving the availability of and interoperability between heterogeneous networked resources.

The converge of the Ubiquitous Computing and the Semantic Web service arise three main issues in this respect which are, 1) how to encapsulate these data resources produced from mobile devices? and 2) based on the encapsulation, how to retrieve clients request? and 3) how to adapt clients query in dynamically environments? In this paper, we address the above three issues from a application-level perspective. For the first issue, We propose a data service to encapsulate one or more possibly distributed and heterogeneous Ubiquitous data sets produced by mobile devices or sensor devices. To deal with heterogeneity of data schemas, we suggest to describe Ubiquitous data sets as views over a shared mediated schema [21]. Specifically, the local schema of each Ubiquitous data source is mapped to concepts of a shared OWL ontology, and its terms are used to define Views [4] [12] which describe the Ubiquitous data sets in the mediated schema. We use the DS Profile to describe content and capabilities of the DS which encapsulate the Ubiquitous data sources. For the second issue, we propose a DS Composition-based query processing approach. By a query-rewriting based approach to composing data services that take advantage of ontology language and efficiency of query-rewriting-based planning, we can effectively achieve clients query request. As for the third issue, we adopt a dynamic evolvable approach to producing and publishing data service that make the data service more adaptable to client quest. The approach we proposed distinguishes itself by its capability of dynamically evolving service interface enabled by describing service capability using the semantic web languages. …

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