Verificare: a platform for composable verification with application to SDN-Enabled systems

Software-Defined Networking (SDN) has become increasing prevalent in both the academic and industrial communities. A new class of system built on SDNs, which we refer to as SDN-Enabled, provide programmatic interfaces between the SDN controller and the larger distributed system. Existing tools for SDN verification and analysis are insufficiently expressive to capture this composition of a network and a larger distributed system. Generic verification systems are an infeasible solution, due to their monolithic approach to modeling and rapid state-space explosion. In this thesis we present a new compositional approach to system modeling and verification that is particularly appropriate for SDN-Enabled systems. Compositional models may have sub-components (such as switches and end-hosts) modified, added, or removed with only minimal, isolated changes. Furthermore, invariants may be defined over the composed system that restrict its behavior, allowing assumptions to be added or removed and for components to be abstracted away into the service guarantee that they provide (such as guaranteed packet arrival). Finally, compositional modeling can minimize the size of the state space to be verified by taking advantage of known model structure. We also present the Verificare platform, a tool chain for building compositional models in our modeling language and automatically compiling them to multiple off-the-shelf verification tools. The compiler outputs a minimal, calculus-oblivious formalism, which is accessed by plugins via a translation API. This enables a wide variety of requirements to be verified. As new tools become available, the translator can easily be extended with plugins to support them

Virtual Node - To Achieve Temporal Isolation and Predictable Integration of Real-Time Components

We present an approach of two-level deployment process for component models used in distributed real-time embedded systems to achieve predictable integration of real-time components. Our main emphasis is on the new concept of virtual node with the use of a hierarchical scheduling technique. Virtual nodes are used as means to achieve predictable integration of software components with real-time requirements. The hierarchical scheduling framework is used to achieve temporal isolation between components (or sets of components). Our approach permits detailed analysis, e.g., with respect to timing, of virtual nodes and this analysis is also reusable with the reuse of virtual nodes. Hence virtual node preserves real-time properties across reuse and integration in different contexts

Connecting ProCom and REMES

Abstrac

ProCom middleware

The goal of this thesis is to develop and implement parts of a middleware that provides necessary support for the execution of ProCom components on top of the real-time operating system FreeRTOS. The ProCom is a component model for embedded systems developed at Mälardalen University. The primary problem is finding an appropriate balance between the level of abstraction and thoughtful utilization of system resources in embedded devices. The defined target platform has limitations in comparison to general purpose computer. These include constraints in available resources such as memory, CPU or bandwidth together with strict requirements in terms of worst-case response time and reliability. We have to also face the problem of limited debugging facilities or their complete absence. In this project, we have examined differences between several real-time and non real- time operating systems. We focus on finding a common subset of core functions that the system must support in order to ensure adequate support for running designed components. We have also identified and tested the suitable libraries to support different types of communication especially TCP/IP. However, we are keenly aware of the limitations of used communication types for analysis of the behavior of real-time systems.Cílem práce je navhnout a implementovat části midlewaru, který poskytuje nut- nou podporu pro běh ProCom komponent nad real-time operačním systémem FreeRTOS. ProCom je název komponentového modelu pro vestavěné systémy vyvinutý na Mälardalen University. Primární úlohou je nalezení vhodného kompomisu mezi úrovní abstrakce a ohleduplného využívání systémových zdrojů ve vestavěných systémech. Definovaná cílová platforma má mnohé limitující faktory v porovnání s běžným počítačem. K těmto omezením patří zejména omezená paměť, procesor nebo přenosová kapacita komunikačních kanálů a zároveň strikní požadavky na spolehlivost a odezvu systému. Při řešení jsme čelili problému s limitujícími nebo chybějícími technickými prostředky pro odstraňování chyb programu. V práci jsou řešeny problémy s rozdílností operačních systémů bez a s real-time podporou. Zaměřili jsme se na nalezení společné podmnožiny funkcí systému nezbytné pro zajištění adekvátní podpory běhu navržených komponent. Rovněž jsme nalezli a otestovali vhodné knihovny pro různé druhy síťové komunikace zejména TCP/IP, i když jsme si plně vědomi jejich limitů při použití v real-time systémech a analýze jejich chování.Department of Distributed and Dependable SystemsKatedra distribuovaných a spolehlivých systémůMatematicko-fyzikální fakultaFaculty of Mathematics and Physic

Analyzing a Pattern-Based Model of a Real-Time Turntable System

AbstractDesigners of industrial real-time systems are commonly faced with the problem of complex system modeling and analysis, even if a component-based design paradigm is employed. In this paper, we present a case-study in formal modeling and analysis of a turntable system, for which the components are described in the SaveCCM language. The search for general principles underlying the internal structure of our real-time system has motivated us to propose three modeling patterns of common behaviors of real-time components, which can be instantiated in appropriate design contexts. The benefits of such reusable patterns are shown in the case-study, by allowing us to produce easy-to-read and manageable models for the real-time components of the turntable system. Moreover, we believe that the patterns may pave the way toward a generic pattern-based modeling framework targeting real-time systems in particular