Kjeld Høyer Mortensen

CPN/Tools: A Post-WIMP Interface for Editing and Simulating Coloured Petri Nets

CPN/Tools is a major redesign of the popular Design/CPN tool from the University of Aarhus CPN group. The new interface is based on advanced, post-WIMP interaction techniques, including bi-manual interaction, toolglasses and marking menus and a new metaphor for managing the workspace. It challenges traditional ideas about user interfaces, getting rid of pull-down menus, scrollbars, and even selection, while providing the same or greater functionality. It also uses the new and much faster CPN simulator and features incremental syntax checking of the nets. CPN/Tools requires an OpenGL graphics accelerator and will run on all major platforms.

Simulation based performance analysis of web servers

This paper presents a general framework for modeling distributed computing environments for performance analysis by means of Timed Hierarchical Coloured Petri Nets. The proposed framework was used to build and analyze a Coloured Petri Net model of a HTTP web server. Analysis of the performance of the web server model reveals how the web server will respond to changes in the arrival rate of requests, and alternative configurations of the web server model are examined. These are the results of a research project conducted in cooperation between the CPN Centre and Hewlett-Packard Corporation on capacity planning and performance analysis of distributed computing environments.

Automatic code generation method based on coloured Petri net models applied on an access control system

In this paper we describe a method for automatic implementation of systems based on models made by means of Coloured Petri Nets (CP-nets or CPN). The Design/CPN tool has been extended in order to support this method. We do not describe the algorithms and data-structures used to implement the code generation tool but rather the context such a tool is used in. The contribution of this work origins from the fact that the code used to simulate the CPN model and the code used to generate the final system implementation are identical. Hence the behaviour of the model and final system are the same, and analysis results found by means of Design/CPN also hold for the final running system. This is different from other CPN-based code generati0on methods. Furthermore, since the method is fully automatic the traditional manual implementation phase has been eliminated. Thus the method described in this paper dramatically reduces development time and cost compared with prevailing system development methods where system implementation is accomplished manually. In this paper we demonstrate that the method is usable in practice for an industrial case, namely an access control system developed by the Danish security company Dalcotech A/S. A CPN model was made of a realistic access control system scenario. We describe this model and how Dalcotech applied the automatic code generation method in order to obtain a system implementation quickly and safely. In this way Dalcotech now has the capability to reduce the resources spent on the implementation phase.

Modelling and Analysis of Distributed Program Execution in BETA Using Coloured Petri Nets

Recently, abstractions supporting distributed program execution in the object-oriented language BETA have been designed. A BETA object on one computer may invoke a remote object, i.e., an object hosted by another computer. In this project, the formalism of Coloured Petri Nets (CP-nets or CPN) is used to describe and analyse the protocol for remote object invocation. In the first place, we build a model in order to describe, understand, and improve the protocol. Remote object invocation in BETA is modelled on the level of threads (lightweight processes) with emphasis on the competition for access to critical regions and shared resources. Secondly, the model is analysed. It is formally proved that it has a set of desirable properties, e.g., absence of dead markings.

Modelling the Work Flow of a Nuclear Waste Management Program

In this paper we describe a modelling project to improve a nuclear waste management program in charge of the creation of a new system for the permanent disposal of nuclear waste.

CPN/Tools: A Tool for Editing and Simulating Coloured Petri Nets ETAPS Tool Demonstration Related to TACAS

CPN/Tools is a major redesign of the popular Design/CPN tool for editing, simulation and state space analysis of Coloured Petri Nets. The new interface is based on advanced interaction techniques, including bi-manual interaction, toolglasses and marking menus and a new metaphor for managing the workspace. It challenges traditional ideas about user interfaces, getting rid of pull-down menus, scrollbars, and even selection, while providing the same or greater functionality. CPN/Tools requires an OpenGL graphics accelerator and will run on all major platforms (Windows, Unix/Linux, MacOS).

Teaching Coloured Petri Nets- A Gentle Introduction to Formal Methods in a Distributed Systems Course

This paper is about the two compulsory project assignments set to the students in an undergraduate course on distributed systems. In the first assignment the students design and validate a non-trivial layered protocol by means of Coloured Petri Nets, and in the second they implement the designed protocol in an object-oriented language. From the two assignments the students experience that Coloured Petri Nets, as a formal method, are useful for designing and analysing distributed systems. In the course students are introduced to basic concepts and techniques for distributed systems, and it is explained that such systems are often too complex to manage without using formal methods. In this paper we also report on our experience with teaching the course and describe the didactic methods applied. Based on the obtained experience we conclude that the combination of distributed systems and Coloured Petri Nets is fruitful — the two areas complement each other. Although our experiences origin in Coloured Petri Nets, we believe that many of our observations hold for other formal methods as well.

CPN/tools: revisiting the desktop metaphor with post-WIMP interaction techniques

CPN/Tools is an editor and simulator of Coloured Petri Nets that uses post-WIMP interaction techniques, including bi-manual interaction, toolglasses and marking menus and a new metaphor for managing the workspace. It challenges traditional ideas about user interfaces, getting rid of pull-down menus, scrollbars, and even selection, while providing the same or greater functionality than current GUIs. This demo presents the first version of CPN/Tools.

Distance-Based Access Modifiers Applied to Safety in Home Networks

Home networks and the interconnection of home appliances is a classical theme in ubiquitous computing research. Security is a recurring concern, but there is a lack of awareness of safety: preventing the computerized house from harming the inhabitants, even in a worst-case scenario where an unauthorized user gains remote control of the facilities. We address this safety issue at the middleware level by restricting the operations that can be performed on devices according to the physical location of the user initiating the request. Operations that pose a potential safety hazard can only be performed within a physical proximity that ensures safety.