Business process modeling flexibility: A formal interpretation

Domain experts from both the software and business process modelling domains concur on the importance of having concurring and co-supportive business and software development processes. This is especially important for organisations that develop software for regulated domains where the software development processes need to abide by the requirements of the domain-specific quality assurance standards. In practice, even when following quite mature development processes to develop high assurance systems, software development is a complex activity that typically involves frequent deviations and requires considerable context-sensitive flexibility. We took a business process modelling notation called PML that was specifically designed to be lightweight and allow flexibility, and developed formal semantics for it. PML supports a range of context-sensitive interpretations, from an open-to-interpretation guide for intended behaviour, to requiring a precise order in which tasks must occur. We are using Unifying Theories of Programming (UTP) to model this range of semantic interpretations and the paper presents a high-level view of our formal semantics for PML. We provide examples that illustrate the need for flexibility and how formal semantics can be used to analyse the equivalence of, or refinement between, strict, flexible, and weak semantics. The formal semantics are intended as the basis for tool support for process analysis and have applications in organisations that operate in regulated domains, covering such areas as the certification process for medical device software.