The development of safety critical software applications has always been done in accordance to strict methods. These systems require the application of verification techniques that guarantee safety properties. Often, ...
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ISBN:
(纸本)076952561X
The development of safety critical software applications has always been done in accordance to strict methods. These systems require the application of verification techniques that guarantee safety properties. Often, they are complex systems that require the integration of different types of engineers such as safety engineers and software architects. Currently, different groups of engineers apply different analysis and modeling techniques (e.g. architectural description languages, and safety analysis models);these differences create inconsistencies between different types of model. In this paper we introduce some solutions to reduce these problems in some safety architectures. These solutions integrate developing modeling languages such as UML and specific safely analysis languages such as FTA and FMECA.
The network connectivity is a basic requirement while implementing fundamental communication and storage abstractions in P2P networks, featuring scalability and fault-tolerance. The quality of services of abstractions...
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ISBN:
(纸本)076952561X
The network connectivity is a basic requirement while implementing fundamental communication and storage abstractions in P2P networks, featuring scalability and fault-tolerance. The quality of services of abstractions like for example multicast, publish/subscribe, group membership or persistent storage is strongly related to the connectivity degree of the underlying overlay. Intuitively, a higher overlay connectivity ensures a reinforced reliability and consequently, the deployment of distributed applications with real-time constraints on top of these overlays becomes feasible even in environments characterized by a high dynamicity, i.e., nodes arriving and departing at a high rate. Our paper proposes a novel delta-connected DHT-free P2P overlay. Our overlay offers strong connectivity guarantees despite the system dynamicity. The construction and the maintenance of our overlay is completely decentralized and handled strictly locally, through deterministic algorithms whose correctness is rigorously proved.
A transactional agent is a mobile agent to manipulate objects distributed on computers with some type of commitment condition. For example, a transactional agent commits only if at least one object could be successful...
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ISBN:
(纸本)076952561X
A transactional agent is a mobile agent to manipulate objects distributed on computers with some type of commitment condition. For example, a transactional agent commits only if at least one object could be successfully manipulated in the at-least-one commitment condition. Computers may stop by fault while networks are assumed to be reliable. In the client-server model, servers can be fault-tolerant according to traditional replication and checkpointing technologies. However, an application program cannot be performed if a client computer is faulty An application program can be performed on another operational computer even if a computer is faulty in the transactional agent model. For example, a transactional agent can move to another operational computer if some destination computer where the agent to move is faulty There are kinds of faulty computers for a transactional agent, current, destination, and sibling computers where a transactional agent now exist, will move, and has visited, respectively. We discuss how the transactinal agent can be tolerant of the types of faults. We show how a program reliably manipulating objects can be realized in a mobile agent in presence of computer faults.
Dynasoar is an infrastructure for dynamically deploying Web services over a grid or the Internet. It enables an approach to grid computing in which distributed applications are built around services instead of jobs. D...
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Dynasoar is an infrastructure for dynamically deploying Web services over a grid or the Internet. It enables an approach to grid computing in which distributed applications are built around services instead of jobs. Dynasoar automatically deploys a service on an available host if no existing deployments exist, or if performance requirements cannot be met by existing deployments. This is analogous to remote job scheduling, but offers the opportunity for improved performance as the cost of moving and deploying the service can be shared across the processing of many messages. A key feature of the architecture is that it makes a clear separation between Web service providers, who offer services to consumers, and host providers, who offer computational resources on which services can be deployed, and messages sent to them processed. Separating these two components and defining their interactions, opens up the opportunity for interesting new organisational/business models
service overlays that support distributed stream processing applications are increasingly being deployed in wide-area environments. The inherent heterogeneous, dynamic and large-scale nature of these systems makes it ...
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service overlays that support distributed stream processing applications are increasingly being deployed in wide-area environments. The inherent heterogeneous, dynamic and large-scale nature of these systems makes it difficult to meet the quality of service (QoS) requirements of the distributed stream processing applications. In this paper we address the load balancing problem for distributed stream processing applications and present a decentralized and adaptive algorithm that allows the composition of distributed stream processing applications on the fly across a large-scale system, while satisfying their QoS demands. The algorithm fairly distributes the load on the resources and adapts dynamically to changes in the resource utilization or the QoS requirements of the applications. Our experimental results demonstrate the scalability, efficiency and performance of our approach
Developing real-time software for large-scale distributedreal-time and embedded (DRE) systems is hard due to variabilities that arise from (I) integration with various subsystems based on different programming langua...
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Developing real-time software for large-scale distributedreal-time and embedded (DRE) systems is hard due to variabilities that arise from (I) integration with various subsystems based on different programming languages and hardware, OS, middleware platforms, (2) fine tuning the system to satisfy a range of customer requirements, such as various quality-of-service (QoS) properties, and (3) changing functional and QoS properties of the system based on available system resources. This paper describes our experience applying model-driven development (MDD) tools and QoS-enabled component middleware technologies to address domain- and middleware-specific variability challenges in an inventory tracking system, which manages the storage and flow of items in warehouses. Our results show that (I) coherent integration of MDD tools and component middleware can provide a productive software process for developing DRE systems by modularizing and composing variability concerns and (2) significant challenges remain that must be overcome to apply these technologies to a broader range of DRE systems
The fault tolerance provided by FT-CORBA is basically static, that is, once the fault tolerance properties of a group of replicated processes are defined, they cannot be modified in runtime. A support for dynamic reco...
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The fault tolerance provided by FT-CORBA is basically static, that is, once the fault tolerance properties of a group of replicated processes are defined, they cannot be modified in runtime. A support for dynamic reconfiguration of the replication would be highly advantageous since it would allow the implementation of mechanisms for adaptive fault tolerance, enabling FT-CORBA to adapt to the changes that can occur in the execution environment. In this paper, we propose a set of extensions to the FT-CORBA infrastructure in the form of interfaces and objectservice implementations, enabling it to support dynamic reconfiguration of the replication
service-oriented architecture has the major advantage of enabling rapid composition of distributed applications from various services, and has become increasingly popular for many large-scale service-based systems in ...
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service-oriented architecture has the major advantage of enabling rapid composition of distributed applications from various services, and has become increasingly popular for many large-scale service-based systems in various application areas, including scientific collaboration, e-business, health care, military, and homeland security. Situation awareness (SAW) is the capability of the entities in a service-based system to be aware of the situation changes and automatically adapt themselves to such changes to satisfy user requirements, including security and privacy. The continuing evolutions of the entities and environment makes SAW one of the most desired features to support dynamic adaptive computing in service-based systems. In this paper, the relationship between contexts/situations and services in situation-aware service-based systems is identified and an extension of OWL-S with situation ontology, called SAW-OWL-S, incorporates SAW in service specifications is presented. An approach to generating service specifications for situation-aware service-based systems using SAW-OWL-S and the system diagram of situation-aware service-based systems using SAW-OWL-S are presented
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