Timed Automata Semantics for Analyzing Creol

We give a real-time semantics for the concurrent, object-oriented modeling language Creol, by mapping Creol processes to a network of timed automata. We can use our semantics to verify real time properties of Creol objects, in particular to see whether processes can be scheduled correctly and meet their end-to-end deadlines. Real-time Creol can be useful for analyzing, for instance, abstract models of multi-core embedded systems. We show how analysis can be done in Uppaal.Comment: In Proceedings FOCLASA 2010, arXiv:1007.499

Time At Your Service: Schedulability Analysis of Real-Time and Distributed Services

The software today is distributed over several processing units. At a large scale this may span over the globe via the internet, or at the micro scale, a software may be distributed on several small processing units embedded in one device. Real-time distributed software and services need to be timely and respond to the requests in time. The Quality of Service of real time software depends on how it schedules its tasks to be executed. The state of the art in programming distributed software, like in Java, the scheduling is left to the underlying infrastructure and in particular the operating system, which is not anymore in the control of the applications. In this thesis, we introduce a software paradigm based on object orientation in which real-time concurrent objects are enabled to specify their own scheduling strategy. We developed high-level formal models for specifying distributed software based on this paradigm in which the quality of service requirements are specified as deadlines on performing and finishing tasks. At this level we developed techniques to verify that these requirements are satisfied. This research has opened the way to a new approach to modeling and analysis of a range of applications such as continuous planning in the context of logistics software in a dynamic environment as well as developing software for multi-core systems. Industrial companies (DEAL services) and research centers (the Uppsala Programming for Multicore Architectures Resrearch Center UPMARC) have already shown interest in the results of this thesis.LEI Universiteit LeidenFoundations of Software Technolog

Programming and deployment of active objects with application-level scheduling

We extend and implement a modeling language based on concurrent active objects with application-level scheduling policies. The language allows a programmer to assign pri-orities at the application level, for example, to method def-initions and method invocations, and assign corresponding policies to the individual active objects for scheduling the messages. Thus, we leverage scheduling and performance related issues, which are becoming increasingly important in multi-core and cloud applications, from the underlying operating system to the application level. We describe a tool-set to transform models of active objects extended with application-level scheduling policies into Java. This tool-set allows a direct use of Java class libraries; thus, we obtain a full-fledged programming language based on active objects which allows for high-level control of deployment related is-sues

Programming and Deployment of Active Objects with Application-Level Scheduling

We extend and implement a modeling language based on concurrent active objects with application-level scheduling policies. The language allows a programmer to assign pri- orities at the application level, for example, to method def- initions and method invocations, and assign corresponding policies to the individual active objects for scheduling the messages. Thus, we leverage scheduling and performance related issues, which are becoming increasingly important in multi-core and cloud applications, from the underlying operating system to the application level. We describe a tool-set to transform models of active objects extended with application-level scheduling policies into Java. This tool-set allows a direct use of Java class libraries; thus, we obtain a full-fledged programming language based on active objects which allows for high-level control of deployment related is- sues

Symmetry and partial order reduction techniques in model checking Rebeca

Rebeca is an actor-based language with formal semantics that can be used in modeling concurrent and distributed software and protocols. In this paper, we study the application of partial order and symmetry reduction techniques to model checking dynamic Rebeca models. Finding symmetry based equivalence classes of states is in general a difficult problem known to be as hard as graph isomorphism. We show how, for Rebeca models, we can tackle this problem with a polynomial-time solution. Moreover, the coarse-grained interleaving semantics of Rebeca causes considerable reductions when partial order reduction is applied. We have also developed a tool that can make use of both techniques in combination or separately. The evaluation results show significant improvements in model size and model-checking time

Monitoring method call sequences using annotations

In this paper we introduce JMSeq, a Java-based tool for monitoring sequences of method calls. JMSeq provides a simple but expressive language to specify the observables of a Java program in terms of sequences of possibly nested method calls. Similar to many monitoring-oriented environments, verification in JMSeq is done at run-time; unlike all other approaches based on aspect-oriented programming, JMSeq uses code annotation rather than instrumentation, and therefore is suitable for component-based software verification

Modelling and Simulation of Asynchronous Real-Time Systems using Timed Rebeca

In this paper we propose an extension of the Rebeca language that can be used to model distributed and asynchronous systems with timing constraints. We provide the formal semantics of the language using Structural Operational Semantics, and show its expressiveness by means of examples. We developed a tool for automated translation from timed Rebeca to the Erlang language, which provides a first implementation of timed Rebeca. We can use the tool to set the parameters of timed Rebeca models, which represent the environment and component variables, and use McErlang to run multiple simulations for different settings. Timed Rebeca restricts the modeller to a pure asynchronous actor-based paradigm, where the structure of the model represents the service oriented architecture, while the computational model matches the network infrastructure. Simulation is shown to be an effective analysis support, specially where model checking faces almost immediate state explosion in an asynchronous setting.Comment: In Proceedings FOCLASA 2011, arXiv:1107.584

Compositional schedulability analysis of real-time actor-based systems

We present an extension of the actor model with real-time, including deadlines associated with messages, and explicit application-level scheduling policies, e.g.,"earliest deadline first" which can be associated with individual actors. Schedulability analysis in this setting amounts to checking whether, given a scheduling policy for each actor, every task is processed within its designated deadline. To check schedulability, we introduce a compositional automata-theoretic approach, based on maximal use of model checking combined with testing. Behavioral interfaces define what an actor expects from the environment, and the deadlines for messages given these assumptions. We use model checking to verify that actors match their behavioral interfaces. We extend timed automata refinement with the notion of deadlines and use it to define compatibility of actor environments with the behavioral interfaces. Model checking of compatibility is computationally hard, so we propose a special testing process. We show that the analyses are decidable and automate the process using the Uppaal model checke