Francesco Pupo

Java based distributed measurement systems

This paper focuses on the development of distributed measurement systems using Java and Web tools. An approach is proposed which is based on object-oriented programming and client/server communications and which allows remote configuration and monitoring of the measurement system. The approach proves useful both for educational and industrial measurement requirements.

Distributed measurement systems: An object-oriented architecture and a case study

This paper is concerned with the software development of distributed real-time measurement systems. Major goals are modularity, reusability and independency from hardware devices, processors and comunications networks. A light-weight architecture for real-time (DART) is proposed which delivers a systematic methodology centred on object-oriented techniques. The effectiveness of DART is illustrated by means of its application to a distributed measurement system for electrical power plants.

Schedulability analysis of real time actor systems using coloured petri nets

This paper proposes a modular and real-time actor language which addresses timing predictability through a holistic integration of an application with its operating software, i.e., scheduling algorithm. The actor language fosters a development life cycle where the same concepts and entities migrate unchanged from specification down to design and object-oriented implementation. The paper concentrates on the specification and analysis of distributed real-time systems using Coloured Petri Nets. Both functional and temporal properties can be validated by simulation and occurrence graphs in the context of the Design/CPN tools.

A modular approach to real-time programming using actors and Java☆

Abstract This paper describes an actor-based approach to real-time programming, which focuses on the separation of functional from timing behaviour. The approach favours modularity and time predictability. Clusters of actors, allocated on distinct processors, are orchestrated by a control machine which provides an event-driven and time-driven customisable scheduling framework. The approach can be hosted by Java, which fosters a clean and type-safe programming style. Temporal analysis can be formally assisted by Coloured Petri Nets.

MADAMS: A software architecture for the management of networked measurement services

MADAMS (Management Architecture for Distributed meAsureMent Services) is a novel service-based software framework designed for publishing, retrieving, configuring, setting up, monitoring and executing distributed measurement services over the Internet. The basic building block is the measurement service, i.e. a software object properly configured and made remote accessible across a network. A measurement service corresponds either to a single (virtual or physical) instrument, or to a collection of measurement services abstracting a test method. Service attributes include the graphical interface which supports user interactions. MADAMS is especially tuned to: (i) defining a common way to manage and use distributed measurement services, (ii) introducing a data-exchange layer for inter-instrument communications, (iii) exploiting a design pattern which separates definition of service functionalities from distribution concerns. This paper introduces MADAMS, outlines its current implementation which depends on Java/Jini, and shows its application to a demand monitoring-control measurement system.

Using Real Time Constraints for Modularisation

This paper advocates an object-oriented approach to the development of distributed real-time systems which clearly separates timing from functional concerns. It also describes a philosophy for modularising, and then designing systems, based on the localisation of timing constraints as one of prime criteria for partitioning. Active objects (i.e., actors) are adopted as the basic building blocks in-the-small. They are not aware of timing constraints nor of scheduling structures. Active objects are in charge of processing messages as they arrive. Message buffering and delivery is the responsibility of a control machine which hosts a reflective scheduler object. Timing constraints express, in general, patterns of multi-object, time-driven co-ordination and synchronisation. The resultant approach improves modularity and object reusability. The paper illustrates the application of the proposed concepts through real world examples.

Multimedia synchronization based on aspect oriented programming

Abstract This paper describes an approach centered on aspect oriented programming (AOP) for controlling the synchronization of distributed multimedia systems. AOP fosters separation of concerns between application objects and synchronization aspects, which naturally arise as cross-cutting concerns. Aspect modularization and encapsulation contribute to re-usability and maintenance of both application components and control mechanisms. The paper illustrates the use of AOP technologies through the construction and evaluation of a real-time quality of service (QoS) filter regulating the QoS at the receiver-side of a multimedia system over the Internet. Aspects are programmed using AspectJ. Particular aspects are exploited for testing the temporal behavior of the synchronized system. Execution experiments make use of Java Media Framework which provides the presentation system.

A Modular Approach to Real Time Programming Using Actors and Java

Abstract This paper describes an actor based approach to real-time programming which focuses on the separation of functional from timing behaviour. The approach favours modularity and time predictability. Clusters of actors, allocated on distinct processors, are orchestrated by a control machine which provides an event-driven and time-driven customisable scheduling framework. The approach can be hosted by Java which fosters a clean and type-safe programming style.

Modelling and simulation of complex systems using TPN Designer

Abstract This paper describes a Java-based simulation toolset––timed Petri nets (TPN) Designer––which supports modelling, discrete-event simulation and performance analysis of modular and complex TPN. A TPN model can be organised as a collection of (possibly hierarchical structured) pages linked to one another by input/output ports. Pages can be replicated so as to build regular topologies like pipeline or grid. The configuration of large models is assisted by a scripting language, which allows connections and set up operations (e.g. for the definition of the initial marking and the parameters of transitions) to be automated. TPN Designer consists of two integrated environments: TPN CAD for graphically designing a TPN model and TPN ENGINE for model compilation, debugging, simulation and statistical data collection. The paper gives an overview to TPN Designer and shows its practical use through examples.

Development of a Schedulability Analysis Framework Based on pTPN and UPPAAL with Stopwatches

This paper proposes an original schedulability framework which is based on preemptive Time Petri Nets (pTPNs) and UPPAAL with stopwatches (UPPAALSW). The realization enables a real-time tasking set, along with precedence constraints in the form of data control, message passing etc., to be uniformly formalized using pTPNs and then analyzed through model checking using UPPAALSW in the presence of a reusable library of template processes modelling transitions of the source pTPNs specification and the scheduler algorithm which can be based on fixed priority or earliest deadline first. The paper first introduces and motivates the proposed approach by relating it to similar work described in literature, then summarizes the pTPNs formalism through a modelling example. After that the prototyped library in UPPAALSW is presented and put to work for model checking the chosen real-time tasking set. Analysis of models which depend e.g. on non deterministic execution times and sporadic arrival times of tasks, is conditioned by the use of an over approximation in the generation of the model state graph.