作者：
Kay KlobedanzWolfgang MuellerAchim RettbergC-LAB
Faculty of Electrical Engineering Computer Science and Mathematics University of Paderborn Paderborn Germany Faculty II
Department Computer Science Carl von Ossietzky University슠of슠Oldenburg Oldenburg Germany
In this paper we present an approach for the self reconfiguration of distributed micro-controllers for increased fault tolerance. Based on a modified distributed system topology utilizing a time division multiple acce...
详细信息
In this paper we present an approach for the self reconfiguration of distributed micro-controllers for increased fault tolerance. Based on a modified distributed system topology utilizing a time division multiple access (TDMA) protocol, i.e., Flex Ray, we present a self-organized distributed coordinator concept which performs the self-reconfiguration in the case of node failures. We introduce a distributed coordinator, which utilizes redundant slots in the Flex Ray communication schedule and combines messages in configured protocol frames and slots to avoid a complete bus restart. As such, the self-reconfiguration is realized by means of predetermined information about resulting changes in the communication dependencies and (re-)assignments determined in the design phase. To retrieve the necessary information, we present an analytical approach, which determines a combined solution for the initial configuration and all possible reconfigurations for the remaining nodes of the Flex Ray network in case of node failures. Hence, through this method we can design self-reconfiguring network-based systems enabling the handling of node failures for an increased fault tolerance.
the complexity of software in safety critical systems has increased significantly over the last ten years so that how to tackle the complexity and gain high dependable software plays an important roles in ensuring the...
详细信息
Testing Web services performance and their Fault Tolerance Mechanisms (FTMs) are crucial for the development of today's applications. Testing the performance and FTMs of composed service systems is hard to measure...
详细信息
Testing Web services performance and their Fault Tolerance Mechanisms (FTMs) are crucial for the development of today's applications. Testing the performance and FTMs of composed service systems is hard to measure at design time because service instability is often caused by the nature of the network. Using a real internet environment for testing is difficult to set up and control. We have developed a fault injection toolkit that emulates a WAN within a LAN environment between composed service components and offers full control over the emulated environments in addition to the ability to inject network-related and application specific faults. the tool also generates background workloads on the tested system for producing more realistic results. We describe an experiment that has been carried out to test the impact of fault tolerance protocols deployed at a service client by using our fault injection toolkit.
the increasing interest in the Internet of things (IoT) has brought lots of opportunities and challenges to researchers. Cyber-space and physical world are more and more amalgamated by smart devices with networking ca...
详细信息
the increasing interest in the Internet of things (IoT) has brought lots of opportunities and challenges to researchers. Cyber-space and physical world are more and more amalgamated by smart devices with networking capability. Making appropriate adaptations to satisfy new processing requirements is necessary for the extensive service in such an environment. In this paper, we propose a three-layer architecture for IoT: the sensor layer, processing layer and mining layer. We adopt a new design approach for the information-processing layer which focuses on five aspects: exchanging data format, data entity design, the method invocation style, the event decoupling and massive data processing. Our approach has been applied to an environmental protection system which is being used in more than 200 monitoring stations in Shanghai. there are 7 kinds of environmental information to be monitored and more than 70 million data items to be processed by this system every day.
Agent-based modeling and simulation is a way to model the behavior of populations of components and their interactions within a system. the key of this approach is to model the components of the system as autonomous a...
详细信息
Agent-based modeling and simulation is a way to model the behavior of populations of components and their interactions within a system. the key of this approach is to model the components of the system as autonomous agents and to simulate their behavior for evaluating the system as a whole. that is very useful for observing the emergence of properties in social, biological, environmental or financial systems, among others. Artificial immune systems, which is a sub field of artificial intelligence, comprises systems modeled by simplifying models from the biological immune system. If agent-based modeling and simulation is used as a laboratory for understanding the biological immune system then, it can also be used for transferring the observed principles into artificial immune system models or for evaluating models that have been already adapted for solving technical problems. this paper presents first, a methodology for transferring principles of the biological immune system into the field of artificial immune systems. then, it presents a brief explanation of the behavior of the cells of the biological immune system, which are treated as internal agents inside a biological organism. Afterwards, the modeling of some selected type of cells and the simulation of the whole simplified system are presented. In the end, the principles of that simplified system are transferred into the design of an alarm management system for the smart grid.
Memory management in Safety-Critical Java (SCJ) is based on time bounded, non garbage collected scoped memory regions used to store temporary objects. Scoped memory regions may have different life times during the exe...
详细信息
Memory management in Safety-Critical Java (SCJ) is based on time bounded, non garbage collected scoped memory regions used to store temporary objects. Scoped memory regions may have different life times during the execution of a program and hence, to avoid leaving dangling pointers, it is necessary to check that reference assignments are performed only from objects in shorter lived scopes to objects in longer lived scopes (or between objects in the same scoped memory area). SCJ offers, compared to the RTSJ, a simplified memory model where only the immortal and mission memory scoped areas are shared between threads and any other scoped region is thread private. In this paper we present how, due to this simplified model, a single scope nesting level can be used to check the legality of every reference assignment. We also show that with simple hardware extensions a processor can see some improvement in terms of execution time for applications where cross-scope references are frequent. Our proposal was implemented and tested on the Java Optimized Processor (JOP).
the scope of this paper is collaborative, distributed safety critical systems which build up a larger scale system of systems (SoS). Systems participating in an SoS follow both global as well as individual goals, whic...
详细信息
the scope of this paper is collaborative, distributed safety critical systems which build up a larger scale system of systems (SoS). Systems participating in an SoS follow both global as well as individual goals, which may be contradicting. Boththe global and local goals of the overall SoS may change over time. Hence, self-adaptive ness, i.e., reconfiguration of the SoS as a reaction on changes within its context is a major characteristic of this systems. the aim of this paper is to describe first steps towards a modeling formalism for SoS in a safety critical context. the challenge is to address on the one hand the required flexibility to adapt the system during run-time and on the other hand to guarantee that the system reacts still in a safe manner. To address these challenges, we propose an approach which guarantees that the system still reacts in a safe manner while adaption to uncertainty including context changes. this adaption has to be assumed as unsafe during design time. the key for having success is to define the interaction between the systems as well as its goals as basic elements of the design. Based on our former work, we propose a well-defined modeling approach for the interaction based on components as basic structural elements, the contract paradigm for the design of the interaction, and graph transformations, which addresses the adaptivity of system of systems. the component model is additionally explicitly enriched by goals, which supports so called evaluation functions to determine the level of target achievement.
As the foundation of cloud computing, Server consolidation allows multiple computer infrastructures running as virtual machines in a single physical node. It improves the utilization of most kinds of resource but memo...
详细信息
As the foundation of cloud computing, Server consolidation allows multiple computer infrastructures running as virtual machines in a single physical node. It improves the utilization of most kinds of resource but memory under x86 architecture. Because of inaccurate memory usage estimate and the lack of memory resource management, there is much service performance degradation in data centers, even though they have occupied a large amount of memory. Furthermore, memory becomes insufficient for a physical server when a lot of virtual machines depend on it. In order to improve this, we present a dynamic memory scheduling system called DMSS, which can manage memory resources in server consolidation environments and allocate memory among virtual machines on demand. We have designed and implemented the corresponding memory scheduling policy based on Xen virtualization platform to enhance memory efficiency and achieve service level agreement. the benchmark shows that DMSS can make an accurate and rapid response to memory changes and save more than 30% physical memory with less than 5% performance degradation. DMSS actually brings in economic benefits to cloud service providers because more virtual machines can be accommodated at lower costs.
暂无评论