Contract by systems modelling: A case study on the FDA principles of software validation

Certification has been a concern amongst the software engineering community for the past few decades and is becoming a major concern today. Several organisations, in charge of certification, have published guidance documents to describe this crucial activity. Indeed, these organisations, through their documents, aim to establish a common understanding between software producers and certifiers (evaluators). These guidance documents use natural language in specifying recommendations, because of the wide audience to which they are addressed and the consequent need for simplicity. However, the specification is not sufficiently explicit and precise to be able to impose a contract (obligation) between the two parties. In this paper, we illustrate this problem as it appears in the guidance documents published by the US Food and Drug Administration (FDA) to validate medical device software. By bearing in mind the clear distinction between products and processes, we use the Product/process (P/p) method to model the "Quality Planning" activity of the FDA validation approach. By using P/p modelling, we present a simplified representation for the FDA validation activities. In essence, the P/p methodology takes a general systems approach. It is appropriate to a variety of areas and has proven its applicability in many fields.