The Topological Functioning Model as a Reference Model for Software Functional and Non-functional Requirements

Specification of non-functional requirements in models is a challenge due to extra-functional nature of the requirements. The topological functioning model (TFM) can serve as a reference model for specifying mappings from both functional and non-functional requirements to the functional characteristics and structure of the modelled system. The main principle presented in this paper extends a way of specification of the TFM functional characteristics and causal relationships and provides a specification of mapping types as tuples of TFM functional features extended with requirements and characteristics of these relationships, namely, completeness and overlapping for functional requirements, and scope and dynamic characteristics for nonfunctional ones. This allows propagating the mappings from requirements to software implementing constructs, that would be useful for further architectural decisions and development of test cases.