Abstract. This paper describes the application of the Real-Time Maude tool to the formal specification and analysis of the CASH scheduling algorithm and its suggested modifications. The CASH algorithm is a sophisticated state-of-the-art scheduling algorithm with advanced capacity sharing features for reusing unused execution budgets. Because the number of elements in the queue of unused resources can grow beyond any bound, the CASH algorithm poses challenges to its formal specification and analysis. Real-Time Maude extends the rewriting logic tool Maude to support formal specification and analysis of object-based real-time systems. It emphasizes generality of specification and supports a spectrum of analysis methods, including symbolic simulation and (unbounded and time-bounded) reachability analysis and LTL model checking. We show how we have used Real-Time Maude to experiment with different design modifications of the CASH algorithm using both Monte Carlo simulation and reachability analysis. We could quickly and easily specify and analyze these modifications using Real-Time Maude, and discovered subtle behaviors in the modifications that lead to missed deadlines. 1

A Biomedical Sensor Network (BSN) is a small-size sensor network for medical applications, that may contain tens of sensor nodes. In this paper, we present a formal model for BSNs using timed automata, where the sensor nodes communicate using the Chipcon CC2420 transceiver (developed by Texas Instruments) according to the IEEE 802.15.4 standard. Based on the model, we have used UPPAAL to validate and tune the temporal configuration parameters of a BSN in order to meet desired QoS requirements on network connectivity, packet delivery ratio and end-to-end delay. The network studied allows dynamic reconfigurations of the network topology due to the temporally switching of sensor nodes to power-down mode for energy-saving or their physical movements. Both the simulator and modelchecker of UPPAAL are used to analyze the average-case and worst-case behaviours. To enhance the scalability of the tool, we have implemented a (new text-based) version of the UPPAAL simulator optimized for exploring symbolic traces of automata containing large data structures such as matrices. Our experiments show that even though the main feature of the tool is model checking, it is also a promising and competitive tool for efficient simulation and parameter tuning. The simulator scales well; it can easily handle up to 50 nodes in our experiments. The model checker installed on a notebook can also deal with networks with 5 up to 16 nodes within minutes depending on the properties checked; these are BSNs of reasonable size for medical applications. Finally, to study the accuracy of our model and analysis results, we compare simulation results by UP-PAAL for two medical scenarios with traditional simulation techniques. The comparison shows that our analysis results coincide closely with simulation results by OMNeT++, a widely used simulation tool for wireless sensor networks. The work is supported by EC IST project CREDO. All models for the experiments of this work can be found at

Many distributed applications can be understood in terms of components interacting in an open environment. This interaction is not always uniform as the network may consist of subnets with different quality: Some components are tightly connected with order preservation of communicated messages, whereas others are more loosely connected such that overtaking of messages and even message loss may occur. Furthermore, certain components may communicate over wireless networks, where sending and receiving must be synchronized, since the wireless medium cannot buffer messages. This paper proposes a formal framework for such systems, which allows high-level modeling and formal analysis of distributed systems where interaction is managed by a variety of nets, including wireless ones. We introduce a simple modeling language for objectoriented components, extending the Creol language. An operational semantics for the language is defined in rewriting logic, which directly provides an executable implementation in Maude.

Abstract. This paper describes the main features of several tools concerned with the analysis of either Maude specifications, or of extensions of such specifications: the ITP, MTT, CRC, ChC, and SCC tools, and Real-Time Maude for real-time systems. These tools, together with Maude itself and its searching and model-checking capabilities constitute Maude’s formal environment. 1

This paper presents criteria that guarantee completeness of Real-Time Maude search and temporal logic model checking analyses, under the maximal time sampling strategy, for a large class of real-time systems. As a special case, we characterize simple conditions for such completeness for object-oriented real-time systems, and show that these conditions can often be easily proved even for large and complex systems, such as advanced wireless sensor network algorithms and active network multicast protocols. Our results provide completeness and decidability of time-bounded search and model checking for a large and useful class of dense-time non-Zeno real-time systems far beyond the class of automaton-based real-time systems for which well known decision procedures exist. For discrete time, our results justify stutteringbisimilar abstractions that can drastically reduce the state space to make search and model checking analyses feasible.