Enhancing Software Interoperability Through Virtual Knowledge Graphs From Object-Oriented APIs

In engineering disciplines such as mechanical or automation engineering, data exchange between different software often relies on non-standardized interfaces. While Semantic Web technologies (SWTs) offer solutions for efficient and versatile data exchange, the majority of software in engineering lack interfaces based on these technologies. Previous research has explored approaches to abstract structured data from external sources as virtual knowledge graphs (VKGs). In this work, we propose an approach to create VKGs from data available via the APIs of engineering software, enabling the querying of engineering data through SWTs and thus facilitating standardized data exchange. We first mathematically introduce the components of APIs of object-oriented software, including classes, their hierarchical relationships, attributes, and instances. We then define formulas to derive the triples of the VKG representing the components, as well as resulting triples according to RDFS entailment rules. Finally, we define a procedure based on the aforementioned formulas, which enables querying the VKG using triple patterns. This provides access to the VKG representing the software-internal data without materialization, in line with the concept ofvirtual. We provide a general implementation of the approach, supporting triple pattern and SPARQL queries, and a software-specific adaption for a particular engineering software. Using this, we demonstrate the capabilities of the approach through an industrial use case. The performance characteristics of the approach are evaluated by analyzing query execution times and scaling behavior across different query types and graph sizes, in comparison with equivalent materialized graphs.