16-04-2013, 03:40 PM
Semantic Digital Library Services
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Abstract
To a great extent, ‘Semantics’ depends upon the context in which the user is seeking information. The proposed model aims at delivering information in the light of ontology-based document annotation, user annotation and domain ontology. The present study addresses the problem of semantic interoperability in digital library environment. In a heterogeneous environment, a mediation-based service is of immense help to resolve the ontology-level, schema-level and service-level ambiguity, for which WSMO Framework has been chosen. This study is confined to bring interoperability at schema and ontology level for the domain of agricultural. Further studies can be done for service level interoperability among various digital library services.
INTRODUCTION
The faster and meaningful information retrieval has been the driving aim for the information retrieval systems since the beginning of automated information retrieval. During the database information systems, Artificial intelligence, and other computer-aided retrieval systems have made a very optimistic start. In the Internet era, Semantic Web came as a model of semantic retrieval in the web environment. Traditional libraries are in a stage of transition towards making the library without boundary with global access with Internet. Many information storage and retrieval systems were been used for a meaningful retrieval in print-based libraries. In a Web environment, the traditional means and techniques for information storage and retrieval are required to be modified to suite the changed needs. The classification systems for book classification has been changed into Ontologies to represent domain knowledge in machine processable form; the cataloguing codes have taken shape of Metadata Schema for the description web resources.
METADATA INTEROPERABILITY FOR SEMANTIC RETRIEVAL
There is wide variety of metadata schemas available for different kind of digital resources. In the classification table for metadata, Kashyap and Seth [3] has categorized the various types of metadata under the following broad categories:
• Content independent metadata
• Content dependent metadata
o Direct content-based metadata
o Content descriptive metadata
- Domain independent metadata
- Domain specific metadata
With this categorization make it quite clear that to bring semantic interoperability among bibliographic repositories, various types of metadata schemas has to be considered. JeromeDL [4] project has made an effort to bring semantic interoperability among the digital repositories using different bibliographic metadata standards like Dublin Core, BibTeX, MARC21 etc. The WSMO framework is a well define model to bring semantic interoperability among
heterogeneous automated retrieval systems by it’s the key components like Web Service Modeling Ontology (WSMO) [5], Web Services Modeling Environment (WSMX) [6] including various mediators.
VIRTUAL DOCUMENT DELIVERY SERVICE
The above two approaches are planned to be incorporated as a virtual document delivery service. The proposed service aims at context-based and interoperable service at metadata level. The domain of agriculture has been chosen for implementing this service among various repositories from agriculture domain. Various agriculture metadata schemas and thesaurus has been studies which are used by the
METHODOLOGY
In the above model of virtual document delivery (fig. 2), the key tasks are: service discovery, ontology mediation and context matching. The semantic digital library searches for the service registry [7, 8] to locate appropriate repositories. After the service discovery to map the ontology and metadata schema, ontology mediators are used. The ontology mediator converts the mapped ontology to the native syntax. The retrieved document description used to generate context-based index. This context-based index is then matched with the user query and annotation.
RELATED WORKS
Context-based retrieval: Context-based information retrieval system has been a major focus of research. The Context Ontology Language (CoOL) [11] is an ontology-based context modeling approach, which uses the Aspect-Scale-Context (ASC) model where each aspect (e.g. spatial distance) can have several scales (e.g. kilometer scale or mile scale) to express some context information (e.g. 20). Chen et al. [12] propose a context broker architecture (CoBrA) using an ontology to describe persons, places and intentions.
FUTURE RESEARCH AND CONCLUSION
Interoperability in a heterogeneous environment is a broad connotation encompassing syntactic, as well as semantic interoperability. Interoperability at semantic level is a challenging task. In context-sensitive query processing over heterogeneous information resources requires the matching of concepts. Vocabularies, semantic relationships and mappings are information objects themselves, their life cycle: creation, acquisition, collection, modeling, identification, integration, mediation, search, use, maintenance and preservation etc. is of primary importance and a necessary prerequisite to improved semantic interoperability [9]. Steps are to be taken in all future researches in this regard.