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Providing fine-grained access control for Java programs via binary editing

Concurrency and Computation: Practice and Experience 2000年第14期12卷

作者： Raju Pandey Brant Hashii Parallel and Distributed Computing Laboratory Computer Science Department University of California Davis CA 95616 U.S.A.

There is considerable interest in programs that can migrate from one host to another and execute. Mobile programs are appealing because they support efficient utilization of network resources and extensibility of information servers. However, since they cross administrative domains, they have the ability to access and possibly misuse a host's protected resources. In this paper, we present a novel approach for controlling and protecting a site's resources. In this approach, a site uses a declarative policy language to specify a set of constraints on accesses to resources. A set of code transformation tools enforces these constraints on mobile programs by integrating the access constraint checking code directly into the mobile program and resource definitions. Using this approach, a site does not need to explicitly include calls to reference monitors in order to protect resources. The performance analysis show that the approach performs better than reference monitor-based approaches in many cases. Copyright © 2000 John Wiley & Sons, Ltd.

关键词： security policy mobile code access control Java object orientation binary editing

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Providing dynamic and customizable caching policies 2

Providing dynamic and customizable caching policies

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2nd USENIX Symposium on Internet Technologies and Systems, USITS 1999

作者： Barnes, J. Fritz Pandey, Raju Parallel and Distributed Computing Laboratory Computer Science Department University of California DavisCA95616 United States

Web caching has emerged as one solution for improving client latency on the web. Cache effectiveness depends on the policies used to route requests to other caches and servers, to maintain up-to-date web objects and to remove objects from the cache. Traditional caches apply one set of policies, which determines the efficiency as well as the effectiveness of the caches. This set of policies often does not exploit the diversity inherent in different web objects, caches and clients. Policies that do exploit this diversity result in convoluted caching policies that attempt to combine multiple policies and guess at the unknown characteristics of web objects, caches and clients. In this paper, we present an extensible caching infrastructure in which cache administrators, servers, and end users can customize how web objects are cached, replaced, and kept consistent. The infrastructure includes a domain-specific language, CacheL, for defining customizable caching policies that can be changed dynamically. Analysis of our prototype, PoliSquid, shows the benefits of the infrastructure for variable coherency policies, localized removal policies, and early removal of objects from servers. © 1999 by The USENIX Association All Rights Reserved.

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CPU resource control for mobile programs 1

CPU resource control for mobile programs

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1st International Symposium on Agent Systems and Applications and 3rd International Symposium on Mobile Agents, ASA/MA 1999

作者： Lal, Manoj Pandey, Raju Computer Science Department Parallel and Distributed Computing Laboratory University of California DavisCA95616 United States

ISBN: (纸本)0769503403

There is considerable interest in developing runtime infrastructures for programs that can migrate from one host to another. Mobile programs are appealing because they support efficient utilization of network resources and extensibility of information servers. This paper presents a scheduling scheme for allocating resources to a mix of real-Time and non real-Time mobile programs. Within this framework, both mobile programs and hosts can specify constraints on how CPU should be allocated. On the basis of the constraints, the scheme constructs a scheduling graph on which it applies several scheduling algorithms. In case of conflicts between mobile program and host specified constraints, the schemes implements a policy that resolves the conflicts in favor of the host. The resulting scheduling scheme is adaptive, flexible, and enforces both program and host specified constraints.

关键词： Scheduling algorithms

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Design issues for a high-performance distributed shared memory on symmetrical multiprocessor clusters

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Cluster computing 1999年第3期2卷 177-186页

作者： Roy, Sumit Chaudhary, Vipin Parallel and Distributed Computing Laboratory Department of Electrical and Computer Engineering Wayne State University Detroit USA

Clusters of Symmetrical Multiprocessors (SMPs) have recently become the norm for high-performance economical computing solutions. Multiple nodes in a cluster can be used for parallel programming using a message passing library. An alternate approach is to use a software distributed Shared Memory (DSM) to provide a view of shared memory to the application programmer. This paper describes Strings, a high performance distributed shared memory system designed for such SMP clusters. The distinguishing feature of this system is the use of a fully multi-threaded runtime system, using kernel level threads. Strings allows multiple application threads to be run on each node in a cluster. Since most modern UNIX systems can multiplex these threads on kernel level light weight processes, applications written using Strings can exploit multiple processors on a SMP machine. This paper describes some of the architectural details of the system and illustrates the performance improvements with benchmark programs from the SPLASH-2 suite, some computational kernels as well as a full fledged application. It is found that using multiple processes on SMP nodes provides good speedups only for a few of the programs. Multiple application threads can improve the performance in some cases, but other programs show a slowdown. If kernel threads are used additionally, the overall performance improves significantly in all programs tested. Other design decisions also have a beneficial impact, though to a lesser degree.

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CPU resource control for mobile programs

CPU resource control for mobile programs

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International Symposium on Agent Systems and Applications. International Symposium on Mobile Agents

作者： M. Lal R. Pandey Parallel and Distributed Computing Laboratory Computer Science Department University of California Davis CA USA

There is considerable interest in developing runtime infrastructures for programs that can migrate from one host to another. Mobile programs are appealing because they support efficient utilization of network resources and extensibility of information servers. This paper presents a scheduling scheme for allocating resources to a mix of real-time and non real-time mobile programs. Within this framework, both mobile programs and hosts can specify constraints on how CPU should be allocated. On the basis of the constraints, the scheme constructs a scheduling graph on which it applies several scheduling algorithms. In case of conflicts between mobile program and host specified constraints, the schemes implement a policy that resolves the conflicts in favor of the host. The resulting scheduling scheme is adaptive, flexible, and enforces both program and host specified constraints.

关键词： Scheduling algorithm Resource management Java Web pages Government Security Concurrent computing Laboratories Computer science Runtime

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The visual query language for an object-oriented knowledge-based system

The visual query language for an object-oriented knowledge-b...

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International Symposium on Database Applications in Non-Traditional Environments, DANTE

作者： Ming Xu Yong-Jun Wang Yi-Jie Wang Kang Zhang Yanchun Zhang National Laboratory for parallel and Distributed Processing Changsha Hunan China Department of Computing Macquarie University Sydney Australia Department of Mathematics & Computing University of Southern Queensland Toowoomba Australia

The user interface of the object-oriented knowledge-based system CAOBS/v1.2 is a visual query subsystem consisting of a flexible visual query language (VKQL), and a knowledge base browser/editor. With the visual language, the user can express query requirements by constructing query graphs. VKQL absorbs the key features of some existing visual query languages, and adds more advanced functions. The paper presents the design and implementation of VKQL and compares VKQL with other similar query languages.

关键词： Database languages Knowledge based systems Computer aided software engineering

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Load-sensitive routing of long-lived IP flows 99

Load-sensitive routing of long-lived IP flows

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Proceedings of the conference on Applications, technologies, architectures, and protocols for computer communication

作者： Anees Shaikh Jennifer Rexford Kang G. Shin Real-Time Computing Laboratory Department of EECS University of Michigan Ann Arbor MI Network Mathematics Research Networking and Distributed Systems AT&T Labs - Research Florham Park NJ

ISBN: (纸本)9781581131352

Internet service providers face a daunting challenge in provisioning network resources, due to the rapid growth of the Internet and wide fluctuations in the underlying traffic patterns. The ability of dynamic routing to circumvent congested links and improve application performance makes it a valuable traffic engineering tool. However, deployment of load-sensitive routing is hampered by the overheads imposed by link-state update propagation, path selection, and signaling. Under reasonable protocol and computational overheads, traditional approaches to load-sensitive routing of IP traffic are ineffective, and can introduce significant route flapping, since paths are selected based on out-of-date link-state information. Although stability is improved by performing load-sensitive routing at the flow level, flapping still occurs, because most IP flows have a short duration relative to the desired frequency of link-state updates. To address the efficiency and stability challenges of load-sensitive routing, we introduce a new hybrid approach that performs dynamic routing of long-lived flows, while forwarding short-lived flows on static preprovisioned paths. By relating the detection of long-lived flows to the timescale of link-state update messages in the routing protocol, route stability is considerably improved. Through simulation experiments using a one-week ISP packet trace, we show that our hybrid approach significantly outperforms traditional static and dynamic routing schemes, by reacting to fluctuations in network load without introducing route flapping.

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Data management for large-scale scientific computations in high performance distributed systems

Data management for large-scale scientific computations in h...

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International Symposium on High Performance distributed computing

作者： A. Choudhary M. Kandemir H. Nagesh J. No X. Shen V. Taylor S. More R. Thakur Center for Parallel and Distributed Computing Department of Electrical and Computer Engineering Northwestern University Evanston IL USA Mathematics and Computer Science Division Argonne National Laboratory Argonne IL USA

With the increasing number of scientific applications manipulating huge amounts of data, effective data management is an increasingly important problem. Unfortunately, so far the solutions to this data management problem either require deep understanding of specific storage architectures and file layouts (as in high-performance file systems) or produce unsatisfactory I/O performance in exchange for ease-of-use and portability (as in relational DBMSs). In this paper we present a new environment which is built around an active meta-data management system (MDMS). The key components of our three-tiered architecture are user application, the MDMS, and a hierarchical storage system (HSS). Our environment overcomes the performance problems of pure database-oriented solutions, while maintaining their advantages in terms of ease-of-use and portability. The high levels of performance are achieved by the MDMS, with the aid of user-specified directives. Our environment supports a simple, easy-to-use yet powerful user interface, leaving the task of choosing appropriate I/O techniques to the MDMS. We discuss the importance of an active MDMS and show how the three components, namely application, the MDMS, and the HSS, fit together. We also report performance numbers from our initial implementation and illustrate that significant improvements are made possible without undue programming effort.

关键词： Large-scale systems distributed computing High performance computing Data visualization Engineering management Concurrent computing Relational databases Art Data analysis Image analysis

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Scalable flow control for multicast ABR services

Scalable flow control for multicast ABR services

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IEEE Annual Joint Conference: INFOCOM, IEEE Computer and Communications Societies

作者： Xi Zhang K.G. Shin D. Saha D. Kandlur Real-Time Computing Laboratory EECS Department University of Michigan Ann Arbor MI USA Network Systems Department IBM Thomas J. Watson Research Center Yorktown Heights NY USA

We propose a flow control scheme for multicast ABR services in ATM networks. At the heart of the proposed scheme is an optimal second-order rate control algorithm, called the /spl alpha/-control, designed to deal with the variation in RM-cell round-trip time (RTT) resulting from dynamic "drift" of the bottleneck in a multicast tree. Applying two-dimensional rate control, the proposed scheme makes the rate process converge to the available bandwidth of the connection's most congested link. It also confines the buffer occupancy to a target regime bounded by a finite buffer capacity. It works well irrespective of the topology of the multicast tree. Using the fluid approximation, we model the proposed scheme and analyze the system dynamics for multicast ABR traffic. We study the convergence properties and derive the optimal control conditions for the /spl alpha/-control. The analytical results show that the scheme is stable and efficient in the sense that both the source rate and bottleneck queue length rapidly converge to a small neighborhood of the designated operating point. We present simulation results which verify the analytical observations. The simulation results also demonstrate the effectiveness of the proposed scheme in dealing with RM-cell RTT and link-bandwidth variations, and in achieving fairness in both buffer and bandwidth occupancies.

关键词： Optimal control Bandwidth Heart Multicast algorithms Algorithm design and analysis Topology Fluid dynamics Traffic control Convergence Queueing analysis

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Modeling and design of notarial system supporting secure transactions in electronic commerce based on the Internet

Modeling and design of notarial system supporting secure tra...

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International Conference on Information networking

作者： Sung-Woo Tak Ryu-Seok Bae Jong-Moon Son Distributed Computing Laboratory Network Computing Department Systems Engineering Research Institute Daejeon South Korea

ISBN: (纸本)0818672250

In this paper, we analyze notarial requirements in the electronic commerce based on the Internet and design the notarial system to support secure transactions, which provides the notarial service for assurance of transactions between customer and merchant running shopping mall connected to the Internet. We suggest that electronic commerce should offer not only authentication service but also notarial service in order to provide secure transactions over the Internet.

关键词： Electronic commerce Authentication Web and internet services Access control IP networks distributed computing Cryptography Transaction databases Protocols Intelligent networks

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