A Formal Semantics of Data Flow Diagrams

This document presents a full version of the formal semantics of data ow diagrams reported in [Larsen&93]. Data Flow Diagrams are used in Structured Analysis and are based on an abstract model for data flow transformations. The semantics consists of a collection of VDM functions, transforming an abstract syntax representation of a data flow diagram into an abstract syntax representation of a VDM specification. Since this transformation is executable, it becomes possible to provide a software analyst/designer with two `views' of the system being modeled: a graphical view in terms of a data flow diagram, and a textual view in terms of a VDM specification. The specification presented in this document have been processed by The IFAD VDM-SL Toolbox [Lassen93] and the LATEX output is produced directly by means of this tool. The complete transformation has been syntax-checked, type-checked and tested using the IFAD VDM-SL Toolbox [Lassen93]; this has given us confidence that the transformation..