The ability to efficiently discover information using partial knowledge (for example keywords, attributes or ranges) is important in large, decentralized, resource sharing distributed environments such as computationa...
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(纸本)9780769519654
The ability to efficiently discover information using partial knowledge (for example keywords, attributes or ranges) is important in large, decentralized, resource sharing distributed environments such as computational grids and peer-to-peer (P2P) storage and retrieval systems. This paper presents a P2P information discovery system that supports flexible queries using partial keywords and wildcards, and range queries. It guarantees that all existing data elements that match a query are found with bounded costs in terms of number of messages and number of peers involved. The key innovation is a dimension reducing indexing scheme that effectively maps the multidimensional information space to physical peers. The design, implementation and experimental evaluation of the system are presented.
It is a well-known fact that software documentation is, in practice, poor and incomplete. Though specification, design, and test documents-among other things-are required by standards and capability maturity models (e...
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It is a well-known fact that software documentation is, in practice, poor and incomplete. Though specification, design, and test documents-among other things-are required by standards and capability maturity models (e.g., SEI CMM), such documentation does not exist in a complete and consistent form in most organizations. When documents are produced, they tend to follow no defined standard and lack information that is crucial to make them understandable and usable by developers and maintainers. Then a fundamental practical question, which motivated this keynote address, is to better understand what type of documentation is required, what is needed to support its completeness and consistency, and what is the level of precision required for each type of document. These questions cannot be investigated at that level of generality though. Answers are likely to be very context-dependent if they are to be precise. We focus our attention here on object-oriented development and the Unified Modeling Language (UML).
This article is a first attempt towards a comprehensive, systematic methodology for class interface testing in the context of client/server relationships. The proposed approach builds on and combines existing techniqu...
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This article is a first attempt towards a comprehensive, systematic methodology for class interface testing in the context of client/server relationships. The proposed approach builds on and combines existing techniques. It first consists in selecting a subset of the method sequences defined for the class testing of the client class, based on an analysis of the interactions between the client and the server methods. Coupling information is then used to determine the conditions, i.e., values for parameters and data members, under which the selected client method sequences are to be executed so as to exercise the interaction. The approach is illustrated by means of an abstract example and its cost-effectiveness is evaluated through a case study.
We previously developed a framework, Hydra, for adding formal semantics to a collection of UML diagrams that enable the automated derivation of formal language specifications for those diagrams. Recently, we have also...
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In this paper we present the design, implementation and evaluation of the Grid-enabled Discover middleware substrate. The middleware substrate enables Grid infrastructure services provided by the Globus Toolkit (secur...
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Computational Grids are emerging as a new infrastructure for Internet-based parallel and distributed computing. They enable the sharing, exchange, discovery, and aggregation of resources distributed across multiple ad...
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Computational Grids are emerging as a new infrastructure for Internet-based parallel and distributed computing. They enable the sharing, exchange, discovery, and aggregation of resources distributed across multiple administrative domains, organizations and enterprises. To accomplish this, Grids need infrastructure that supports various services: security, uniform access, resource management, scheduling, application composition, computational economy, and accounting. Although several initiatives are engaged in the development of Grid technologies, Grid accounting issues are yet to be addressed. To overcome this limitation, we propose a new infrastructure called GridBank that provides services for accounting. The support of computational economy and accounting services can lead to a self-regulated accountability in Grid computing. This paper presents requirements of Grid accounting and different economic models within which it can operate and proposes a Grid Accounting Services Architecture to meet them. The paper highlights implementation issues with a detailed discussion on the format for various records/databases that the GridBank needs to maintain. It also presents protocols for interaction between the GridBank and various components within Grid computing environments.
At the 2001 IEEE International Conference on Data Mining in San Jose, California,on November 29 to December 2, 2001, there was a panel discussion on how datamining research meets practical development. One of the moti...
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RDT is a graphical formal modeling language in which the modeler works by constructing diagrams of the processes in their model which they join together to form complete systems. Aside from the benefits which accrue a...
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RDT is a graphical formal modeling language in which the modeler works by constructing diagrams of the processes in their model which they join together to form complete systems. Aside from the benefits which accrue as a side effect of building a formal model of a proposed systems, these diagrammatic models can be useful as a means of communication between the development team and the users. However one of the greatest benefits of a formal model is that it can be subjected to rigorous examination to ensure that it satisfies properties required of the system. This paper describes the transformation used by the RDT toolset to generate Promela code (the input language of the SPIN model-checker) automatically from a model.
Path probing is essential to maintaining an efficient overlay network topology. However, the cost of a full-scale probing is as high as O(n/sup 2/), which is prohibitive in large-scale overlay networks. Several method...
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Path probing is essential to maintaining an efficient overlay network topology. However, the cost of a full-scale probing is as high as O(n/sup 2/), which is prohibitive in large-scale overlay networks. Several methods have been proposed to reduce probing overhead, although at a cost in terms of probing completeness. In this paper, an orthogonal solution is proposed that trades probing overhead for estimation accuracy in sparse networks such as the Internet. The proposed solution uses network-level path composition information (for example, as provided by a topology server) to infer path quality without full-scale probing. The inference metrics include latency, loss rate and available bandwidth. This approach is used to design several probing algorithms, which are evaluated through analysis and simulation. The results show that the proposed method can significantly reduce probing overhead while providing hounded quality estimations for all n /spl times/ (n - 1) overlay paths. The solution is well suited to medium-scale overlay networks in the Internet. In other environments, it can be combined with extant probing algorithms to further improve performance.
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