In modern business enterprises, it is frequent to develop an integrated application to provide uniform access to multiple existing information systems running internally or externally of the enterprise. Data integration is a pervasive challenge faced by these applications that need to query across multiple autonomous and heterogeneous data sources. Integrating such diverse information systems becomes a challenging task particularly when different applications use different data formats and query languages which are not compatible with each other. Hence, the data integration tools have to provide the optimal solution to mitigate the heterogeneity in data formats and query languages. The goal of this thesis is to provide better means to easily and dynamically integrate distributed heterogeneous web data sources (particularly XML and RDF data sources) in such a way that the user can easily build data integration applications. The main topic of this work is devoted to the distributed heterogeneous data integration for web data sources using DeXIN approach, while data concerns aware querying system provides data concerns assurance and DeXIN mashup tool provides an easy to use interface.