  The Semantic Web, an extension of the current web, provides a common
framework that makes data machine understandable and also allows data to be
shared and reused across various applications. Resource Description Framework
(RDF), a graph-based data model for describing things (entities), facilitates
data integration. Due to the explosion of the amount of RDF data, developing
tools to support processing and answering of complex queries over the
integrated data has become challenging. To overcome this challenge in query
processing in semantic data integration frameworks, we provide a view layer
inserted between the heterogeneous data sources and user interface layer while
ensuring only authorized users are allowed access to the information. The view
layer must provide a support in terms of access, integration, querying,
management of data sources in a multi-user environment.
