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International Conference on Dependable systems and Networks (DSN)

作者： S.S. Kulkarni A. Ebnenasir Software Engineering and Network Systems Laboratory Department of Computer Science and Engineering Michigan State University East Lansing MI USA

We concentrate on automated synthesis of multitolerant programs, i.e., programs that tolerate multiple classes of faults and provide a (possibly) different level of fault-tolerance to each class. We consider three levels of fault-tolerance: (1) failsafe, where in the presence of faults, the synthesized program guarantees safety, (2) nonmasking, where in the presence of faults, the synthesized program recovers to states from where its safety and liveness are satisfied, and (3) masking where in the presence of faults the synthesized program satisfies safety and recovers to states from where its safety and liveness are satisfied. We focus on the automated synthesis of finite-state multitolerant programs in high atomicity model where the program can read and write all its variables in an atomic step. We show that if one needs to add failsafe (respectively, nonmasking) fault-tolerance to one class of faults and masking fault-tolerance to another class of faults then such addition can be done in polynomial time in the state space of the fault-intolerant program. However, if one needs to add failsafe fault-tolerance to one class of faults and nonmasking fault-tolerance to another class of faults then the resulting problem is NP-complete. We find this result to be counterintuitive since adding failsafe and nonmasking fault-tolerance to the same class of faults (which is equivalent to adding masking fault-tolerance to that class of faults) can be done in polynomial time, whereas adding failsafe fault-tolerance to one class of faults and nonmasking fault-tolerance to a different class of faults is NP-complete.

关键词： Fault tolerance Safety Fault tolerant systems Network synthesis Polynomials software engineering Laboratories computer science State-space methods engineering profession

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On quality-of-service and energy consumption tradeoffs in FEC-encoded audio streaming

On quality-of-service and energy consumption tradeoffs in FE...

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International Workshop on Quality of Service

作者： Z. Zhou P.K. McKinley S.M. Sadjadi Software Engineering and Network Systems Laboratory Department of Computer Science and Engineering Michigan State University East Lansing MI USA

This paper addresses the energy consumption of forward error correction (FEC) protocols as used to improve quality-of-service (QoS) for wireless computing devices. The paper also characterizes the effect on energy consumption and QoS of the power saving mode in 802.11 wireless local area networks (WLANs). Experiments are described in which FEC-encoded audio streams are multicast to mobile computers across a WLAN. Results of these experiments quantify the tradeoffs between improved QoS, due to FEC, and additional energy consumption caused by receiving and decoding redundant packets. Two different approaches to FEC are compared relative to these metrics. The results of this study enable the development of adaptive software mechanisms that attempt to manage these tradeoffs in the presence of highly dynamic wireless environments.

关键词： Quality of service Energy consumption Streaming media Forward error correction Wireless LAN Wireless application protocol Mobile computing Decoding Environmental management software development management

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A distributed approach to topology-aware overlay path monitoring

A distributed approach to topology-aware overlay path monito...

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International Conference on Distributed Computing systems

作者： C. Tang P.K. McKinley Software Engineering and Network Systems Laboratory Department of Computer Science and Engineering Michigan State University East Lansing MI USA

Path probing is essential to maintain an efficient overlay network topology. However, the cost of complete probing can be as high as O(n/sup 2/), which is prohibitive in large-scale overlay networks. Recently we proposed a method that trades probing overhead for inference accuracy in sparse networks such as the Internet. The method uses physical path information to infer path quality for all of the n/spl times/(n-1) overlay paths, while actually probing only a subset of the paths. We propose and evaluate a distributed approach to implement this method. We describe a minimum diameter, link-stress bounded overlay spanning tree, which is used to collect and disseminate path quality information. All nodes in the tree collaborate to infer the quality of all paths. Simulation results show this approach can achieve a high-level of inference accuracy while reducing probing overhead and balancing link stress on the spanning tree.

关键词： Peer to peer computing Network topology Stress Probes IP networks Routing Bandwidth Delay computerized monitoring software engineering

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Transparent self-optimization in existing CORBA applications

Transparent self-optimization in existing CORBA applications

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International Conference on Autonomic Computing (ICAC)

作者： S.M. Sadjadi P.K. McKinley Software Engineering and Network Systems Laboratory Department of Computer Science and Engineering Michigan State University East Lansing MI USA

This paper addresses the design of adaptive middleware to support autonomic computing in pervasive computing environments. The particular problem we address here is how to support self-optimization to changing network connection capabilities as a mobile user interacts with heterogeneous elements in a wireless network infrastructure. The goal is to enable self-optimization to such changes transparently with respect to the core application code. We propose a solution based on the use of the generic proxy, which is a specific CORBA object that can intercept and process any CORBA request using rules and actions that can be introduced to the knowledge base of the proxy during execution. To explore its design and operation, we have incorporated the generic proxy into ACT (Sadjadi and McKinley, 2004), an adaptive middleware framework we designed previously to support adaptation in CORBA applications. Details of the generic proxy are presented. A case study is described in which a generic proxy is used to support self-optimization in an existing image retrieval application, when executed in a heterogeneous wireless environment.

关键词： Middleware Communication system security computer networks Pervasive computing Wireless networks Military computing Intelligent networks Application software software engineering computer science

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Automated analysis of timing information in UML diagrams 04

Automated analysis of timing information in UML diagrams

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IEEE International Conference on Automated software engineering (ASE)

作者： S. Konrad L.A. Campbell B.H.C. Cheng Software Engineering and Network Systems Laboratory Department of Computer Science and Engineering Michigan State University East Lansing MI USA

ISBN: (纸本)9780769521312

This work introduces an approach to adding timing information to UML diagrams for modeling embedded systems. In order to perform automated formal analysis of these UML diagrams with timing information, we extend a previously developed UML formalization framework to provide Promela semantics for the timing elements of the UML diagrams. The paper describes the application of our approach to an electronically controlled steering system obtained from one of our industrial collaborators.

关键词： Information analysis Timing Unified modeling language Embedded system Performance analysis Automatic control Control systems Steering systems Electrical equipment industry Electronics industry

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Generation of self-optimizing wireless network applications

Generation of self-optimizing wireless network applications

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International Conference on Autonomic Computing (ICAC)

作者： S.M. Sadjadi P.K. McKinley R.E.K. Stirewalt B.H.C. Cheng Software Engineering and Network Systems Laboratory Department of Computer Science and Engineering Michigan State University East Lansing MI USA

Adaptable applications are difficult to develop and maintain especially if adaptive code, which implements the adaptive behavior, is tangled into functional code, which implements the imperative behavior. Our work investigates how to wrap existing applications transparently to generate such management components. Developing manageable components requires some mechanism to support adaptation in behavior. The predominant mechanism for implementing adaptation in object-oriented software is behavioral reflection, which can be used to modify how an object responds to a message. This work describes the application of TRAP/J to a multicast audio application. The audio-streaming application (ASA) is designed to deliver interactive audio from a microphone at one network node to multiple receiving nodes.

关键词： Wireless networks Reflection Application software Quality of service Adaptive coding Wireless LAN software engineering Laboratories computer science Environmental management

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Approximate caches for packet classification

Approximate caches for packet classification

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

作者： F. Chang Wu-chang Feng Kang Li Systems Software Laboratory OGI School of Science and Engineering at OHSU Beaverton OR USA Department of Computer Science University of Georgia Athens GA USA

Many network devices such as routers and firewalls employ caches to take advantage of temporal locality of packet headers in order to speed up packet processing decisions. Traditionally, cache designs trade off time and space with the goal of balancing the overall cost and performance of the device. We examine another axis of the design space that has not been previously considered: accuracy. In particular, we quantify the benefits of relaxing the accuracy of the cache on the cost and performance of packet classification caches. Our cache design is based on the popular Bloom filter data structure. This paper provides a model for optimizing Bloom filters for this purpose, as well as extensions to the data structure to support graceful aging, bounded misclassification rates, and multiple binary predicates. Given this, we show that such caches can provide nearly an order of magnitude cost savings at the expense of misclassifying one billionth of packets for IPv6-based caches.

关键词： Filters Costs Aging Data structures Cache storage System software Laboratories Modems Protocols Classification algorithms

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An authorization model for multimedia digital libraries

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International Journal on Digital Libraries 2004年第3期4卷 139-155页

作者： Kodali, Naren Farkas, Csilla Wijesekera, Duminda Department of Information and Software Engineering George Mason University Fairfax VA 22030-4444 United States Center for Secure Information Systems George Mason University Fairfax VA 22030-4444 United States Information Security Laboratory University of South Carolina Columbia SC 29208 United States Department of Computer Science and Engineering University of South Carolina Columbia SC 29208 United States

In this paper we present a generalized authorization model for multimedia digital libraries. Our aim is to support the enforcement of access control requirements of the original data sources without the need to create a new, unified model for the digital library. We integrate the three most widely used access control models (i.e., mandatory, discretionary, and role-based) within a single framework, allowing seamless accesses to data protected by these security models. In particular, we address the access control needs of continuous media data while supporting quality of service (QoS) requirements and preserving operational semantics. The technical core of the paper focuses on the development of metadata and the corresponding metastructure to represent authorization policies and QoS requirements and shows their applicabilty to continuous media. We define our security objects based on the Synchronized Multimedia Integration Language (SMIL), which controls multimedia presentations. Following the synchronization constructs 〈par〉 and 〈seq〉 of SMIL, we define a normal form for multimedia streams, called SMIL normal form. SMIL normal form provides a syntax-independent representation of semantically equivalent multimedia data. SMIL normal form compositions are extended (decorated) with RDF statements, representing security and QoS metadata. Interpretation of these statements and, therefore, the authorization and QoS requirements of the decorated multimedia object are defined by the metastructure, represented as a DAML+OIL ontology. We propose the concept of generalized subject that encompasses all access permissions of a given user regardless of the multiple permissions in different access control models. Finally, we develop methods to generate secure views for each generalized subject and retrieve them using a secure multimedia server. © Springer-Verlag 2004.

关键词： Access control Continuous media Digital library Metadata Semantics

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Image attachment using fuzzy-genetic algorithms

Image attachment using fuzzy-genetic algorithms

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IEEE International Conference on Fuzzy systems (FUZZ-IEEE)

作者： B. Resko P. Korondi Z. Petres J.F. Bourges H. Hashimoto Japanese-Hungarian Laboratory Budapest University슠of슠Technology슠and슠Economics Hungary Computer Science and Software Engineering Department Laval University Sainte Foy QUE Canada Institute of Industrial Sciences Integrated Intelligent Systems Japanese-Hungarian Laboratory University of Tokyo Tokyo Japan

This paper gives contribution to the construction of an image mosaic by pasting together a sequence of photographs taken by a regular digital camera from the same position but in different directions. In order to find the best match between two overlapping images, a fuzzy-genetic based algorithm is presented. A translation vector with a minimal difference between the common picture parts has to be found. The difference is defined using the fuzzyfied contours of each images. The search of the optimal translation is considered as a minimization process. This paper proposes a method that uses genetic algorithms to find the minimum point corresponding to the optimal translation. Using the fuzzy based comparison of the two images yields a fast fitness function, while the implementation of the proposed method in a genetic hardware has a low and variable computational cost. The precision of the method is inverse-proportional with the computational time, which makes it ideal to be used in real time systems.

关键词： Cameras Genetic algorithms Intelligent systems Laboratories Real time systems Pixel computer industry Industrial economics Informatics software engineering

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On the cost-quality tradeoff in topology-aware overlay path probing 11

On the cost-quality tradeoff in topology-aware overlay path ...

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11th IEEE International Conference on Network Protocols, ICNP 2003

作者： Tang, Chiping McKinley, P.K. Software Engineering and Network Systems Laboratory Department of Computer Science and Engineering Michigan State University East LansingMI48824 United States

ISBN: (纸本)0769520243

Path probing is essential to maintaining an efficient overlay network topology. However, the cost of a full-scale probing is as high as O(n2), 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 × (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. © 2003 IEEE.

关键词： Bandwidth

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