一种基于UPPAAL的Web服务组合模型检测方法

Web服务组合的正确性验证对提高软件开发效率、实现服务增值具有重要意义。为从高层抽象层次研究Web服务组合的正确性及其形式化验证方法,考虑到Web服务组合中的实时特征,在采用软件体系结构描述语言XYZ/ADL对Web服务组合进行描述的基础上,将其实时描述部分XYZ/RE转换至时间自动机模型,组合后系统应满足的性质用分支时序逻辑CTL公式表示,最后应用模型检测工具UPPAAL实现了Web服务组合正确性的自动化验证。

时间自动机关于LTL性质的符号化模型检测工具及其改进

许多系统需要在规定时间内响应外部发生的事件，并迅速完成对事件的处理，这样的系统称之为实时系统。实时系统经常出现在与生命财产安全息息相关的领域，如果无法及时响应外部事件，可能会造成十分严重的后果。如何保证实时系统的正确性、可靠性受到越来越广泛的关注。 模型检测是一种对系统进行形式化验证的算法，它可以自动的在模型状态空间中搜索不满足规范的路径或状态，设计者可以根据找到的反例修改系统设计，进而提高系统的可靠性。模型检测方法的主要瓶颈是状态爆炸，符号化方法和抽象是延缓状态爆炸发生的重要手段。 时间自动机是一种使用广泛的描述实时系统的数学模型， 时序逻辑LTL是是一种常用的针对实时和并发系统的规范语言，本文主要研究了时间自动机关于LTL性质的符号化模型检测方法，并实现了相应的模型检测工具CTAV。 CTAV以DBM作为表示符号化状态的数据结构，使用DBM的操作和运算完成符号化状态的生成、存储及比较等，它通过on-the-fly的方法在生成系统符号化状态空间的同时进行性质的检测。 本文还研究了最大上下界抽象等在模型检测中的使用，比较了不同的抽象在LTL模型检测中的效果。此外还针对符号化状态的特点，对模型检测过程进行了改进，避免了不必要的状态展开。 为了方便建模，CTAV对UPPAAL模型描述语言进行了支持，并针对检测过程中变量存储的各种情况，设计了一次索引和二次索引的方法提高读写变量的速度。

Safety-critical medical device development using the UPP2SF model translation tool

Software-based control of life-critical embedded systems has become increasingly complex, and to a large extent has come to determine the safety of the human being. For example, implantable cardiac pacemakers have over 80,000 lines of code which are responsible for maintaining the heart within safe operating limits. As firmware-related recalls accounted for over 41% of the 600,000 devices recalled in the last decade, there is a need for rigorous model-driven design tools to generate verified code from verified software models. To this effect, we have developed the UPP2SF model-translation tool, which facilitates automatic conversion of verified models (in UPPAAL) to models that may be simulated and tested (in Simulink/Stateflow). We describe the translation rules that ensure correct model conversion, applicable to a large class of models. We demonstrate how UPP2SF is used in themodel-driven design of a pacemaker whosemodel is (a) designed and verified in UPPAAL (using timed automata), (b) automatically translated to Stateflow for simulation-based testing, and then (c) automatically generated into modular code for hardware-level integration testing of timing-related errors. In addition, we show how UPP2SF may be used for worst-case execution time estimation early in the design stage. Using UPP2SF, we demonstrate the value of integrated end-to-end modeling, verification, code-generation and testing process for complex software-controlled embedded systems. © 2014 ACM.

The MIRELA framework: modeling and analyzing mixed reality applications using timed automata

Mixed Reality (MR) aims to link virtual entities with the real world and has many applications such as military and medical domains [JBL+00, NFB07]. In many MR systems and more precisely in augmented scenes, one needs the application to render the virtual part accurately at the right time. To achieve this, such systems acquire data related to the real world from a set of sensors before rendering virtual entities. A suitable system architecture should minimize the delays to keep the overall system delay (also called end-to-end latency) within the requirements for real-time performance. In this context, we propose a compositional modeling framework for MR software architectures in order to specify, simulate and validate formally the time constraints of such systems. Our approach is first based on a functional decomposition of such systems into generic components. The obtained elements as well as their typical interactions give rise to generic representations in terms of timed automata. A whole system is then obtained as a composition of such defined components. To write specifications, a textual language named MIRELA (MIxed REality LAnguage) is proposed along with the corresponding compilation tools. The generated output contains timed automata in UPPAAL format for simulation and verification of time constraints. These automata may also be used to generate source code skeletons for an implementation on a MR platform. The approach is illustrated first on a small example. A realistic case study is also developed. It is modeled by several timed automata synchronizing through channels and including a large number of time constraints. Both systems have been simulated in UPPAAL and checked against the required behavioral properties.