Real-time systems interact with their environment using time constrained input/output signals. Examples of real-time systems include patient monitoring systems, air traffic control systems, and telecommunication systems. For such systems, a functional misbehavior or a deviation from the specified time constraints may have catastrophic consequences [27]. Therefore, ensuring the correctness of real-time systems becomes necessary. Two different techniques are usually used to cope with the correctness of a software system prior to its deployment, namely, verification and testing. In this paper, we address the issue of testing real-time software systems specified as a Timed Input Output Automaton (TIOA). TIOA is a variant of timed automaton [1], [2], [22], [29]. We introduce the syntax and semantics of TIOA. We present the potential faults that can be encountered in a timed system implementation. We study these different faults based on TIOA model and look at their effects on the execution of the system using the region graph. We present a method for generating timed test cases. This method is based on a state characterization technique and consists of the following three steps: First, we sample the region graph using a suitable granularity, in order to construct a subautomaton easily testable, called Grid Automaton. Then, we transform the Grid Automaton into a Nondeterministic Timed Finite State Machine (NTFSM). Finally, we adapt the Generalized Wp-method [23] to generate timed test cases from NTFSM. We assess the fault coverage of our test cases generation method and prove its ability to detect all the possible faults. Throughout the paper, we use examples to illustrate the various concepts and techniques used in our approach.

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Quality of Service (QoS)

Abstract. Existing approaches about defining formal semantics of commitment usually consider operations as axioms or constrains on top of the commitment semantics, which fail to capture the meaning of interactions that are central to real-life business scenarios. Furthermore, existing semantic frameworks using different logics do not gather the full semantics of commitment operations and semantics of social commitments within the same framework. This paper develops a novel unified semantic model for social commitments and their operations. It proposes a logical model based on a new logic extending CT L * with commitments and operations to specify agent interactions. We also propose a new definition of assignment and delegation operations by considering the relationship between the original and new commitment contents. We prove that the proposed model satisfies some properties that are desirable when modeling agent interactions in MASs and introduce a NetBill protocol as a running example to clarify the automatic verification of this model. Finally, we present an implementation and report on experimental results of this protocol using the NuSMV and MCMAS symbolic model checkers.

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Social commitments have been extensively and effectively used to represent and model business contracts among autonomous agents having competing objectives in a variety of areas (e.g., modeling business processes and commitmentbased protocols). However, the formal verification of social commitments and their fulfillment is still an active research topic. This paper presents CTLC + that modifies CTLC, a temporal logic of commitments for agent communication that extends CTL logic to allow reasoning about communicating commitments and their fulfillment. The verification technique is based on reducing the problem of model checking CTLC + into the problem of model checking ARCTL (the combination of CTL with action formulae) and the problem of model checking GCTL * (a generalized version of CTL * with action formulae) in order to respectively use the extended NuSMV symbolic model checker and the CWB-NC automata-based model checker as a benchmark. We also prove that the reduction techniques are sound and the complexity of model checking CTLC + for concurrent programs with respect to the size of the components of these programs and the length of the formula is PSPACE-complete. This matches the complexity of model checking CTL for concurrent programs as shown by Kupferman et al. We finally provide two case studies taken from business domain along with their respective implementations and experimental results to illustrate the effectiveness and efficiency of the proposed technique. The first one is about the NetBill protocol and the second one considers the Contract Net protocol.