This paper presents a survey of existing event systems structured as a taxonomy of distributed event-based programming systems. Our taxonomy identifies a set of fundamental properties of event-based programming system...
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ISBN:
(纸本)0769515886
This paper presents a survey of existing event systems structured as a taxonomy of distributed event-based programming systems. Our taxonomy identifies a set of fundamental properties of event-based programming systems and categorizes them according to the event model and event service criteria. The event service is further classified according to its organization and interaction model, as well as other functional and non-functional features.(1).
The notion of intrinsic references, i.e. references based on the hash digest of the referent, is introduced and contrasted with that of physical references, where the referent is defined relative to the state of a phy...
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ISBN:
(纸本)0769515886
The notion of intrinsic references, i.e. references based on the hash digest of the referent, is introduced and contrasted with that of physical references, where the referent is defined relative to the state of a physical system, A retrieval mechanism using intrinsic references, the Elephant Store, is presented. The use of intrinsic references in hierarchical data structures is discussed, and the advantages regarding version management, consistency anddistributed storage are argued.
The on-demand downloading of application code over a wireless network is an emerging paradigm for the distributed environment of mobile computing devices. In this environment, a user must wait while a mobile computing...
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ISBN:
(纸本)0769515851
The on-demand downloading of application code over a wireless network is an emerging paradigm for the distributed environment of mobile computing devices. In this environment, a user must wait while a mobile computing device fetches the application code over the network prior to execution. To reduce this downloading latency, we have developed a download approach based on working sets, and have designed and implemented a working-set generator that defines working sets by focusing on the intervals during which a program refers to functions, variables, and constants, The program invocation times with this approach, simulated using trace information obtained from actual program behaviour on Linux, have been compared with those of all-at-once, page, class, and symbol download approaches. This simulation showed that the working-set approach can reduce the download-execution time compared to that with the four other approaches.
This paper proposes a replica control method based on a fairly assigned variation of numerical data that has weak consistency for loosely coupled systems managed or used by different organizations. This method dynamic...
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ISBN:
(纸本)0769515851
This paper proposes a replica control method based on a fairly assigned variation of numerical data that has weak consistency for loosely coupled systems managed or used by different organizations. This method dynamically distributes the variation of numerical data to replicas according to their demands while achieving fairness among them. By assigning the variation, a replica can determine the possibility that processed update transactions will be aborted and can notify a client of the possibility even when network partitioning happens. In addition, fairly assigning the variation of data to replicas enables the disadvantage among replicas caused by asynchronous update to be balanced among replicas. Fairness control for assigning the variation of data is performed by averaging the demands in the variation that are requested by, the replicas. Simulation showed that our system can achieve extremely, high fairness while processing update transactions at the maximum rate.
Peer-to-peer systems have emerged as a popular way to share huge volumes of data. The usability of these systems depends on effective techniques to find and retrieve data;however;current techniques used in existing P2...
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ISBN:
(纸本)0769515851
Peer-to-peer systems have emerged as a popular way to share huge volumes of data. The usability of these systems depends on effective techniques to find and retrieve data;however;current techniques used in existing P2P systems are often very, inefficient. In this paper we present three techniques for efficient search in P2P systems. We present the design of these techniques, and then evaluate them using a combination of analysis and experiments over Gnutella, the largest open P2P system in operation. We show that while our techniques maintain the same quality of results as currently used techniques, the), use zip to 5 times fewer resources. In addition, we designed our techniques to be simple, so that they can be easily incorporated into existing systems for immediate impact.
We present here the execution model of a policy-driven middleware for building secure distributed collaboration systems from their high level specifications. Our specification model supports nested collaboration activ...
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ISBN:
(纸本)0769515851
We present here the execution model of a policy-driven middleware for building secure distributed collaboration systems from their high level specifications. Our specification model supports nested collaboration activities, and uses role-based security policies and event count based coordination specification. From the specifications of a collaboration environment, appropriate policy modules are derived for enforcing security and coordination requirements. A policy-driven distributed middleware provides services to the users to join roles in an activity, perforin role specific operations, or create new, activities. We describe here the design challenges for the middleware and present the runtime structures and protocols supported by it for creating activities, roles, and objects.
We describe Spectra, a remote execution system for battery-powered clients used in pervasive computing. Spectra enables applications to combine the mobility of small devices with the greater processing power of static...
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ISBN:
(纸本)0769515851
We describe Spectra, a remote execution system for battery-powered clients used in pervasive computing. Spectra enables applications to combine the mobility of small devices with the greater processing power of static compute servers. Spectra is se tuning: it monitors both application resource usage and the availability of resources in the environment, and dynamically determines hog, and where to execute application components. In making this determination, Spectra balances the competing goals of performance, energy conservation, and application quality. We have validated Spectra's approach on the Compaq Itsy v2.2 and IBM ThinkPad560X using a speech recognizer a document preparation system, and a natural language translator our results confirm that Spectra almost always selects the best execution plan, and that its few suboptimal choices are very close to optimal.
The Differentiated Services model is the emerging standard to provide Quality-of-Service (QoS) support for the multimedia applications in the future Internet. This model involves bandwidth broker agents to perform the...
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ISBN:
(纸本)0769515851
The Differentiated Services model is the emerging standard to provide Quality-of-Service (QoS) support for the multimedia applications in the future Internet. This model involves bandwidth broker agents to perform the admission control and network, configuration functionalities. A great deal of efforts has been recently devoted to investigate viable approaches to the implementation of mechanisms that automatically perform the bandwidth broker functions. Yet, 170 standard policy has been so far proposed. In this paper;we propose a distributed measurement based protocol that performs admission control functionalities for multicast traffic in diff-serv networks. The protocol supports dynamic changes of the multicast group membership, it operates on-demand and it supports the Premium Service. We prove that the proposed protocol performs an effective and efficient admission control function.
We describe how to manage distributed file system caches based upon groups of files that are accessed together. We use file access patterns to automatically, construct dynamic groupings of files and then manage our ca...
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ISBN:
(纸本)0769515851
We describe how to manage distributed file system caches based upon groups of files that are accessed together. We use file access patterns to automatically, construct dynamic groupings of files and then manage our cache by fetching groups, rather than single files. We present experimental results, based on trace-driven workloads, demonstrating that grouping improves cache performance. At the file system client, grouping can reduce LRU demand fetches by 50 to 60%. At the server cache hit rate improvements are much more pronounced, but vary widely (20 to over 1200%) depending upon the capacity of intervening caches. Our treatment includes information theoretic results that justify our approach to file grouping.
distributed interactive applications such as multiplayer games will become increasingly popular in wide area distributedsystems. To provide the response time desired by, users despite high and unpredictable communica...
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ISBN:
(纸本)0769515851
distributed interactive applications such as multiplayer games will become increasingly popular in wide area distributedsystems. To provide the response time desired by, users despite high and unpredictable communication latency in such systems, shared objects will be replicated or cached by clients that participate in the applications. Any updates to the shared objects will have to be disseminated to clients that actually use the objects to maintain consistency. We address the problem of efficient and scalable update dissemination in an environment where client interests can change dynamically and the number of multicast channels available for update dissemination is limited. We present a heuristic based algorithm that can group objects and clients in a way that it handles limited bandwidth resources. We show that our algorithm can produce better results than several algorithms that have been developed in the past for update dissemination.
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