## 1 Introduction
The primary advantage of OBDA [17] is that it provides end users with consistent access to and a platform for querying multiple data sources, regardless of where the data are stored. It also enables querying through the _Federated Ontology_ (FO) conceptual layer. The FO acts as a mediator, distributing the query to the data sources and retrieving results between entities in the data sources and the ontologies [4; 7; 18]. The proposed _Federated Virtual Knowledge Graph_ (FVKG) framework is recognized as a promising solution to improve DI&SI bottlenecks in response to these challenges. The FVKG presents a cohesive image of disparate relational data sources and related data models through semantic technologies. In this research, we used a _Virtual Knowledge Graph_ (VKG) as an instrumental tool to enable Ontop (virtual system) ([[https://ontop-vkg.org/](https://ontop-vkg.org/)]([https://ontop-vkg.org/](https://ontop-vkg.org/)) (accessed on 21 May 2025)), providing a logical abstraction layer over different data sources(primarily relational) and allowing for seamless querying and analysis without physically consolidating data in the distributed environment of healthcare. This research targets two questions: (i) **RQ1:**_How can ontology engineering paradigms be systematically integrated within design science research to develop data-driven artifacts?_ (ii) **RQ2:**_How can data integration and semantic interoperability bottlenecks be addressed using a virtualized knowledge graph (VKG) approach leveraging the Ontop platform in federated health information systems (HIS)?_  
The significant contributions of this research are to establish a connection between the potential of _Design Science Research_ (DSR) and _Ontology Engineering_ (OE) paradigms to address real-world problems and advance the development of modern HIS. This research integrates the principles of DSR forces with semantic web technologies, such as ontologies and KGs, to foster knowledge creation, engineering, and evolution using a hybrid methodology. We customized _Ontology-based Design Science Research Engineering_ (ODSRE) and extended work from [4,19]. This research also investigates how the FVKG framework, utilizing the VKG approach, can serve as an effective tool for virtual platforms like Ontop, which powers semantic query engines to address and improve DI&SI challenges in building federated HIS. The proposed FVKG framework facilitates a unified platform as a _Global-Virtual-View_ (GVV) for heterogeneous relational data sources [20], disparate models, and ontologies, overcoming data-driven bottlenecks in a distributed environment. FVKG provides a platform that minimizes data integration complexities, ensures low latency and data freshness, facilitates real-time access, and enhances scalability and performance while ensuring integrity and coherence across the federation system through a virtual approach in a distributed environment. The FVKG also integrates OBDA to build a monolithic virtual ontological model (e.g., cardiovascular disease (CVD) model), combining various ontology-driven artifacts and ensuring semantic alignment through schema mapping techniques, especially in the context of cardiovascular disease use cases. This research is structured into the subsequent sections: Section 2 briefly highlights the desktop research related to the Ontology-based Design Science Research (ODSR) framework in HIS, the VKG framework or ODBA, the VKG mapping and tooling ecosystem, and the data federation approach for HIS. Section 3 presents the customized methodology steps, data collection, and data analysis explaining an FVKG's anatomy and its architectural layers. Section 4 displays the experimental results. Section 5 showcases testing and evaluation procedures using DL and SPARQL query languages. Lastly, Section 6 offers a conclusion and future possibilities and directions.