A Model Driven Approach to the Analysis of Timeliness Properties

Abstract. The need for a design language that is rigorous but accessible and intuitive is often at odds with the formal and mathematical nature of languages used for analysis. UML and Petri Nets are a good example of this dichotomy. UML is a widely accepted modelling language capable of modelling the structural and behavioural aspects of a system. However UML lacks the mathematical foundation that is required for rigorous analysis. Petri Nets on the other hand have a strong mathematical base that is well suited for analysis of a system but lacks the appeal and ease-of-use of UML. Design in UML languages such as Sequence Diagrams and analysis in Petri Nets require on one hand some expertise in potentially two incompatible systems and their tools, and on the other a seamless transition from one system to the other. One way of addressing this impediment is to focus the software development mainly on the design language system and to facilitate the transition to the formal analysis by means of a combination of automation and tool support. The aim of this paper is to present a transformation system, which takes UML Sequence Diagrams augmented with time constraints and generates semantically equivalent Petri Nets that preserve the timing requirements. A case study on a small network is used in order to illustrate the proposed approach and in particular the design, the transformation and the analysis processes.

Stream Based Specification of Cryptographic Protocols and Their Composition Properties

The correct development of security-critical systems is very difficult, as demonstrated by many insecure systems that have been developed in research and practice. A particular challenge is the establishment of security properties for separate components in an open, distributed system, in a way that the interaction of these components will still satisfy the security properties established for each component in isolation. We present a methodology to represent crypto-based, distributed systems and software and their composition properties in a formal way using Focus, a framework for formal specification and development of interactive systems. Using this formal representation, one can argue about properties of protocol components and their composition in a methodological wa