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.
Ubiquitous computing promotes the proliferation of various stationary embedded and mobile devices interconnected by heterogeneous networks. It leads to a highly dynamic distributed system with many devices and service...
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ISBN:
(纸本)0769515851
Ubiquitous computing promotes the proliferation of various stationary embedded and mobile devices interconnected by heterogeneous networks. It leads to a highly dynamic distributed system with many devices and services coming and going frequently. Many emerging distributed multimedia applications are being deployed in such a computing environment. In order to make the experience for a user truly seamless and to provide soft performance guarantees, we must meet the following challenges: (1) users should be able to perforin tasks continuously, despite changes of resources, devices and locations;(2) users should be able to efficiently utilize all accessible resources within runtime environments to receive the best possible Quality-of-Service (QoS). In this paper, we propose an integrated QoS-aware service configuration model to address the above problems. The configuration model includes two tiers: (1) service composition tier, which is responsible for choosing and composing current available service components appropriately and coordinating arbitrary, interactions between them to achieve the user's objectives;and (2) service distribution tier, which is responsible for dividing an application into several partitions and distributing them to different available devices appropriately. Our initial experimental results based on both prototype and simulations show the soundness of our model and algorithms.
The need for sharing is well known in a large number of distributed collaborative applications. These applications are difficult to develop for wide area (possibly, mobile) networks because of slow and unreliable conn...
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ISBN:
(纸本)0769515851
The need for sharing is well known in a large number of distributed collaborative applications. These applications are difficult to develop for wide area (possibly, mobile) networks because of slow and unreliable connections. For this purpose, we developed a platform called OB1WAN(1) that: i) allows the application to decide, in run-time, the mechanism by which objects should be invoked, remote method invocation or invocation on a local replica, ii) allows incremental replication of large object graphs, iii) allows the creation of dynamic clusters of data, and iv) provides hooks for the application programmer to implement a set of application specific properties such as relaxed transactional support or updates dissemination. These mechanisms allow an application to deal with situations that frequently occur in a (mobile) wide-area network, such as disconnections and slow links: i) as long as objects needed by an application (or by an agent) are colocated, there is no need to be connected to the network, and ii) it is possible to replace, in run-time, remote by local invocations on replicas, thus improving the performance and adaptability of applications. The prototype is developed in Java, is very small and simple to use, the performance results are very encouraging, and existing applications can be easily modified to take advantage of OB1WAN.
Named Data networking (ndN), a promising Future Internet Architecture design, requires new experimental applications to demonstrate its performance and feasibility. Through designing, implementing, and evaluating ndNM...
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ISBN:
(纸本)9781509044573
Named Data networking (ndN), a promising Future Internet Architecture design, requires new experimental applications to demonstrate its performance and feasibility. Through designing, implementing, and evaluating ndNMaze, i.e., an ndN version of a widely deployed peer-to-peer file-sharing application called IPMaze, we find that ndNMaze has a simpler system architecture with improved performance and flexibility. The innovative messaging mechanism anddistributed hash tables (DHT) in ndNMaze simplified the implementations of key system components such as user management, nearest neighbor discovery, file discovery and distributions. To systematically evaluate the performance, we simulate both versions with NS-3 simulator, and collect a broad range of performance metrics including hop count, data request latency, data request efficiency, and network transmission efficiency. Our experimental results show that ndNMaze achieves better performance than IPMaze due to the ndN's advantages in content-centric data distribution and sharing. Our work sheds light for distributed application design in ndN.
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.
Context-aware mobile computing belongs to the field of ubiquitous computing. It aims to enable device to provide better service for people through applying available context information. In this paper, context-aware m...
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ISBN:
(纸本)9781424442331
Context-aware mobile computing belongs to the field of ubiquitous computing. It aims to enable device to provide better service for people through applying available context information. In this paper, context-aware mobile computing was elaborated Firstly, the history of definition of context was summarized, and then the new classification of human-centric context was proposed The acquiring and application of context information was generalized in the following part. On the basis, the issues in context-aware mobile computing were pointed out and finally the architecture of context-aware Q&A service was presented. Although the context-aware Q&A service can not solve all the issues introduced in this paper, it can be considered as an attempt to provide mobile service through mining of previously gathered context information sensed
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.
With the development of mobile devices, mobile cloud computing is becoming increasingly important. One of the basic questions in mobile cloud computing is how to match user demand with cloud server resources. Based on...
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ISBN:
(纸本)9781509044573
With the development of mobile devices, mobile cloud computing is becoming increasingly important. One of the basic questions in mobile cloud computing is how to match user demand with cloud server resources. Based on Improved FCM (IGAFCM) Algorithm, this paper proposes a scheduling scheme which is provided for mobile resources to cluster continuously, so as to reduce the size of the matching requirements during the search. Moreover, Experiments have proved that matching strategy is dynamically adjusted according to the matching score and feedback training.
This paper indicates that a scalable fault-tolerant name service can be provided utilizing an overlay network and that such a name service can scale along a number of dimensions: it can be sized to support a large num...
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ISBN:
(纸本)0769515851
This paper indicates that a scalable fault-tolerant name service can be provided utilizing an overlay network and that such a name service can scale along a number of dimensions: it can be sized to support a large number of clients, it can allow large numbers of concurrent lookups on the same name or sets of names, and it can provide name lookup latencies measured in seconds. Furthermore, it can enable updates to be made pervasively visible in times typically measured in seconds for update rates of up to hundreds per second. We explain how many of these scaling properties for the name service are obtained by reusing some of the same mechanisms that allowed the underlying overlay network to scale. Finally, we observe that the overlay network is sensitive to bandwidth and CPU limitations.
This paper discusses distributed check-pointing with "Time Warp techniques 11, a typical uncoordinated checkpointing technique that is often used in the parallel anddistributed simulations. Relaxing the assumpti...
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ISBN:
(纸本)0769515886
This paper discusses distributed check-pointing with "Time Warp techniques 11, a typical uncoordinated checkpointing technique that is often used in the parallel anddistributed simulations. Relaxing the assumption of the previous model of Soliman et al., we show a discrete time model where the number of available checkpoints each process can hold is finite. In addition, we propose an adaptive distributed check-pointing technique, that gives an effective time arrangement of check-points for a recovery point distribution, and we give numerical examples.
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