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This paper deals with the new approach in the design of hard real-time control applications where the control requirements as well as computing and communication constraints should be jointly taken into account to design a control...
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This paper deals with the new approach in the design of hard real-time control applications where the control requirements as well as computing and communication constraints should be jointly taken into account to design a control application. Resource distribution and limitation, safety requirements and autonomy lead to the need of the so called co-design, where the integral problem of the design of the control structure, algorithm and its implementation should be tackled together. Along these lines, after a motivation, the interlacing between both design issues is analyzed and new concepts and architectures are proposed.
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Now that multicore microprocessors have become a commodity, it is natural to think about employing them in all kinds of computing, including high-reliability embedded real-time systems. Appealing aspects of this development includ...
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Now that multicore microprocessors have become a commodity, it is natural to think about employing them in all kinds of computing, including high-reliability embedded real-time systems. Appealing aspects of this development include the ability to process more instructions per second and more instructions per watt. However, not all problems are amenable to parallel decomposition, and for those that are, designing a correct scalable solution can be difficult. If there are deadlines or other hard timing constraints the difficulty becomes much greater. This paper reviews some of what is known about multiprocessor scheduling of task systems with deadlines, including recent advances in the analysis of arbitrary sporadic task systems under fixed-priority and earliest-deadline first scheduling polices. It also examines critically the foundations of these theoretical results, including assumptions about task independence and worst-case execution time estimates, with a view toward their practical applicability.
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We promote a model-driven software development that centres on component-orientation. In keeping with Dijkstra's principle of separation of concerns, we want the user design space to be limited to the internals of components - for...
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We promote a model-driven software development that centres on component-orientation. In keeping with Dijkstra's principle of separation of concerns, we want the user design space to be limited to the internals of components - for which strictly sequential functional code is to be used - and the interfaces provided to and required from other components, where extra-functional requirements are declaratively specified by means of annotations. We want the user model to be directly amenable to response time analysis. To this end we prescribe that the component model must statically bind to a computational model that matches the analysis theory in use. We want to ensure semantic preservation across the entire transformation chain, from the user model, to the analysis model, to the implementation model (i.e., the code) and, eventually to the execution environment. The Ada Ravenscar Profile is an excellent candidate implementation language for use in our endeavour. In this paper we present a set of code archetypes written against the constraints of the Ravenscar Profile, which we developed in conformance with our notion of separation of concerns, to drive the model to code transformation step of our development infrastructure.
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In this paper we propose an approach for building real-time systems under a combination of requirements: specification and handling of operating modes and mode changes; implementation on top of a multiprocessor platform; integrati...
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In this paper we propose an approach for building real-time systems under a combination of requirements: specification and handling of operating modes and mode changes; implementation on top of a multiprocessor platform; integration of both aspects within a common framework; and connection with schedulability analysis procedures.The proposed approach uses finite state machines to describe operating modes and transitions, and a framework of real-time utilities that implements the required behaviour in Ada 2012. Automatic code generation plays an important role: the system is derived from the functional and timing specification, and implemented according to the abstractions provided by the framework. Response time analysis enables assessing the schedulability of the different operating modes and the transitions between modes.
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In this paper we discuss how the concept of separation of concerns could be conveniently applied to improve the model-driven component-based development of real-time high-integrity systems. Interpreting Dijkstra's view in this reg...
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In this paper we discuss how the concept of separation of concerns could be conveniently applied to improve the model-driven component-based development of real-time high-integrity systems. Interpreting Dijkstra's view in this regard, we seek separation of concerns between the specification of needs (expressed declaratively by the user as requirements and assumptions) and the conception of a demonstrable solution for them (which we want to implement automatically, in the spirit of model-driven development). We aim to enable software designers to specify the assumptions needed on the expected behavior of the system solely by attaching declarative attributes to the affected elements of the system model. We then want the underlying design environment to produce a solution that provably achieves that behavior at run time. We find this vision to fit very well in a component-based development as it naturally allows the declarative space to be confined to interfaces (for the outside view of components) and operations (for the inside view of them). To prove the viability of our vision we apply it to the handling of synchronization requirements as seen from the perspective of the calling component, which is acutely more challenging than from the standpoint of the provider component.
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This paper describes how a dedicated Time Management Unit (TMU) is used to reduce the overhead of execution time control. While the implementation described here is for Ada 2012 and a GNAT bare-board run-time environment, the prin...
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This paper describes how a dedicated Time Management Unit (TMU) is used to reduce the overhead of execution time control. While the implementation described here is for Ada 2012 and a GNAT bare-board run-time environment, the principles should be applicable to other languages and run-time systems. The TMU has been implemented as a peripheral unit for the Atmel AVR®32 UC3 series of microcontrollers, and test results from simulation with the syntheziable RTL code of this system-on-chip are presented.
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FAA's recent large Ada based En-Route Automation Modernization (ERAM) program has reintegrated many disparate system components into a modern composite architecture. The program must now deliver on its promise to facilitate the ev...
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FAA's recent large Ada based En-Route Automation Modernization (ERAM) program has reintegrated many disparate system components into a modern composite architecture. The program must now deliver on its promise to facilitate the evolution of the U.S. National Airspace System (NAS) by integrating Next Generation Air Traffic Control (ATC) capabilities starting with System Wide Information Management (SWIM), Automatic Dependent Surveillance (ADS-Broadcast) and the En Route Data Communications (Data Comm). One of the major challenges is to implement and leverage more open, flexible interfaces made possible by web service technologies and to ensure reliability and security of high performance data and communications services despite increased reliance on less trusted commercial products. The paper focuses on maturity, problems and lessons learned during the development of the initial SWIM as a Service Oriented Architecture (SOA) extension to the En Route Automation Modernization ERAM System.
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Generics (also known as templates) have become a standard feature of modern programming languages, offering parameterization by data types and possibly other entities. Generics support efficient type-safe container data structures...
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Generics (also known as templates) have become a standard feature of modern programming languages, offering parameterization by data types and possibly other entities. Generics support efficient type-safe container data structures, general-purpose algorithms, and other reusable components. However, the approaches in different languages vary widely in syntax, semantics, and usage. This paper summarizes the design of generics in Ada, C++, C#, and Java and compares them with respect to expressiveness, implementation model / run-time efficiency, and interaction with object-oriented programming and other features.
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We will present a methodology and a tool to generate test cases from a model expressed in Business Process models and a set of test intentions for choosing a particular kind of tests. In order to do this we transform the Business ...
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We will present a methodology and a tool to generate test cases from a model expressed in Business Process models and a set of test intentions for choosing a particular kind of tests. In order to do this we transform the Business Process models in an intermediate format called Algebraic Petri Nets. We then use model checking techniques (e.g. Decision Diagrams) to encode the state space - the semantics - of the model and producing test cases including their oracles according to that transition system.
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An activity is described by a chronicle that expresses relationships between events in a sequence ordered in time. A chronicle language provides a syntax for the different chronicle operators considered. The recognition of chronic...
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An activity is described by a chronicle that expresses relationships between events in a sequence ordered in time. A chronicle language provides a syntax for the different chronicle operators considered. The recognition of chronicles is used in the processing of complex system simulations so as to detect activities or analyse behaviours. This work models formally the chronicle recognition, and coloured Petri nets (CPN) are used to model the recognition of a chronicle within a flow of events. The occurrence of an event to be detected is modelled by the firing of the corresponding transition. We provide coloured Petri nets to model the recognition of chronicles expressed with logical and temporal operators, as well as minimum and maximum time delays. We show how the composition of operators can be modelled by a composition of the coloured subnets associated with the different operators. The algebraic properties of the operators are reflected in the coloured nets. In this work, composition is achieved through place fusion, and a comprehensive modelling is provided, including more delicate issues such as chronicle with repetitions, and the absence of sub-chronicles.
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