Workflow technology is currently being deployed in quite diverse domains. However, the element of change is present in some degree and form in almost all domains. A workflow implementation that does not support the pr...
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Computational intelligence techniques have been successfully used for solving control problems in p ache t-switching network architectures. The introduction of active networking adds a high degree of flexibility in cu...
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作者：
Debusmann, M.Fachhochschule Wiesbaden
University of Applied Sciences Department of Computer Science Distributed Systems Laboratory Kurt-Schumacher-Ring 18 WiesbadenD-65197 Germany
Managing distributed applications results in a large number of routine management tasks to be performed. Thus, the goal of management has to be the automation of these tasks to the greatest possible extent. This autom...
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distributed-system observation tools require an efficient data structure to store and query the partial-order of execution. Such data structures typically use vector timestamps to efficiently answer precedence queries...
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A web crawling system employing a parallel and distributed architecture needs to have a mechanism to bring the whole system in a coordinated state when the nodes are added to or removed from the system. This paper pre...
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A web crawling system employing a parallel and distributed architecture needs to have a mechanism to bring the whole system in a coordinated state when the nodes are added to or removed from the system. This paper presents an efficient dynamic reconfiguration model that can be used in such a system. The study shows that this model leads to some nice properties, such as load balance and low traffic in the system, which contribute to high performance. Currently this model is being implemented in WebGather, a well-known Chinese and English web search engine.
Partial-order data structures used in distributed-system observation tools typically use vector timestamps to efficiently determine event precedence. Unfortunately all current dynamic vector-timestamp algorithms eithe...
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ISBN:
(纸本)0769510779
Partial-order data structures used in distributed-system observation tools typically use vector timestamps to efficiently determine event precedence. Unfortunately all current dynamic vector-timestamp algorithms either require a vector of size equal to the number of processes in the computation or require a graph search operation to determine event precedence. This fundamentally limits the scalability of such observation systems. In this paper we present an algorithm for hierarchical, clustered vector time-stamps. We present results for a variety of computation environments that demonstrate such timestamps can reduce space consumption by more than an order-of-magnitude over Fidge/Mattern timestamps while still providing acceptable time bounds for computing timestamps and determining event precedence.
Global File Store (GFS) is a pervasive computing oriented file storage system. It puts forward an idea - put all files on the Internet. There are 3 features associated with GFS: massive storage, high performance and m...
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Global File Store (GFS) is a pervasive computing oriented file storage system. It puts forward an idea - put all files on the Internet. There are 3 features associated with GFS: massive storage, high performance and mobile computing support. The approach to construct GFS is to implement a layer on top of existing heterogeneous file systems. The above features are realized by means of multiple namespace, extensive use of caching and replication, and highly scalable architecture. The system is in the stage of prototype development.
In this paper, first studied are the distribution characteristics of user behaviors based on log data from a massive web search engine. Analysis shows that stochastic distribution of user queries accords with the char...
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In this paper, first studied are the distribution characteristics of user behaviors based on log data from a massive web search engine. Analysis shows that stochastic distribution of user queries accords with the characteristics of power-law function and exhibits strong similarity, and the user' s queries and clicked URLs present dramatic locality, which implies that query cache and 'hot click' cache can be employed to improve system performance. Then three typical cache replacement policies are compared, including LRU, FIFO, and LFU with attenuation. In addition, the distribution character-istics of web information are also analyzed, which demonstrates that the link popularity and replica pop-ularity of a URL have positive influence on its importance. Finally, variance between the link popularity and user popularity, and variance between replica popularity and user popularity are analyzed, which give us some important insight that helps us improve the ranking algorithms in a search engine.
Voice and circuit switched data will be carried over IP networks in the wireline part of the future UMTS. The commonly used protocol suite for low-bitrate real-time traffic transmission in the Internet leads to large ...
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Voice and circuit switched data will be carried over IP networks in the wireline part of the future UMTS. The commonly used protocol suite for low-bitrate real-time traffic transmission in the Internet leads to large header overhead, i.e., to low utilization of the network resources by user data. Multiplexing packets of different flows into a single IP packet reduces this effect. We model packet tunneling and multiplexing with subsequent spacing in IP networks. We derive a discrete-time analysis based on a framework for solving Markov chains. The numerical results show the superiority of multiplexing schemes provided that parameters are set in an appropriate way since there are many performance tradeoffs that have substantial effect on the efficiency of the system.
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