72,151 research outputs found
TURTLE: Four Weddings and a Tutorial
The paper discusses an educational case study of protocol modelling in TURTLE, a real-time UML profile supported by the open source toolkit TTool. The method associated with TURTLE is step by step illustrated with the connection set up and handover procedures defined for the Future Air navigation Systems. The paper covers the following methodological stages: requirement modeling, use-case driven and scenario based analysis, object-oriented design and rapid prototyping in Java. Emphasis is laid on the formal verification of analysis and design diagrams
Real-time reactive system development : a formal approach based on UML and PVS
The notion of real-time reactive behavior encompasses concurrency, communication through sensors and actuators, and relations between input and output over time. Real-time reactive systems are inherently complex, and often used in safety-critical contexts. Application domains include control systems for nuclear reactors, air traffic, railroad crossing, telecommunications, and medical devices. Applying formal methods in the development process is seen as a means for dealing with the complexity, and for quality assurance. One of the goals is to formally verify time-dependent safety properties in the design. The scope of this thesis encompasses three major components. We develop a visual technique for object-oriented modeling of real-time reactive systems, based on a minimal set of extensions to UML, along with a set of well-formedness rules for the real-time models. We then present a formalization of the Real-Time rules of UML metamodel, and provide formal denotational and operational semantics for RTUML. Finally, we introduce a methodology for mechanized verification of time-dependent properties in the RTUML design of real-time reactive systems, within the PVS verification environment. The formal semantics of RTUML provides a foundation for the verification methodology, and for rigorous analysis and validation techniques. The novelty of the development methodology for real-time systems lies in the mechanized verification approach superimposed on the object-oriented modeling technique
Specification And Runtime Checking Of Timing Constraints In Safety Critical Java
The Java platform is becoming a vital tool for developing real-time and safety-critical systems. Design patterns and the availability of Java libraries, both provide solutions to many known problems. Furthermore, the object-oriented nature of Java simplifies modular development of real-time systems. However, limitations of Java as a programming language for real-time systems are a notable obstacle to producing safe real-time systems. These limitations are found in the unpredictable execution model of the language, due to Java’s garbage collector, and the lack of support for non-functional specification and verification tools. In this dissertation I introduce SafeJML, a specification language for support of functional and non-functional specifications, based on an implementation of a safety-critical Java platform and the Java Modeling Language (JML). This dissertation concentrates on techniques that enable specification and dynamic checking of timing constraints for some important Java features, including methods and subtyping. SafeJML and these dynamic checking techniques allow modular specification and checking of safety-critical systems, including those that use object-orientation and design patterns. Such coding techniques could have maintenance benefits for real-time and safety-critical softwar
Specification and Verification of Distributed Embedded Systems: A Traffic Intersection Product Family
Distributed embedded systems (DESs) are no longer the exception; they are the
rule in many application areas such as avionics, the automotive industry,
traffic systems, sensor networks, and medical devices. Formal DES specification
and verification is challenging due to state space explosion and the need to
support real-time features. This paper reports on an extensive industry-based
case study involving a DES product family for a pedestrian and car 4-way
traffic intersection in which autonomous devices communicate by asynchronous
message passing without a centralized controller. All the safety requirements
and a liveness requirement informally specified in the requirements document
have been formally verified using Real-Time Maude and its model checking
features.Comment: In Proceedings RTRTS 2010, arXiv:1009.398
Modeling and Analyzing Adaptive User-Centric Systems in Real-Time Maude
Pervasive user-centric applications are systems which are meant to sense the
presence, mood, and intentions of users in order to optimize user comfort and
performance. Building such applications requires not only state-of-the art
techniques from artificial intelligence but also sound software engineering
methods for facilitating modular design, runtime adaptation and verification of
critical system requirements.
In this paper we focus on high-level design and analysis, and use the
algebraic rewriting language Real-Time Maude for specifying applications in a
real-time setting. We propose a generic component-based approach for modeling
pervasive user-centric systems and we show how to analyze and prove crucial
properties of the system architecture through model checking and simulation.
For proving time-dependent properties we use Metric Temporal Logic (MTL) and
present analysis algorithms for model checking two subclasses of MTL formulas:
time-bounded response and time-bounded safety MTL formulas. The underlying idea
is to extend the Real-Time Maude model with suitable clocks, to transform the
MTL formulas into LTL formulas over the extended specification, and then to use
the LTL model checker of Maude. It is shown that these analyses are sound and
complete for maximal time sampling. The approach is illustrated by a simple
adaptive advertising scenario in which an adaptive advertisement display can
react to actions of the users in front of the display.Comment: In Proceedings RTRTS 2010, arXiv:1009.398
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