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Kwei-Jay Lin

Bio: Kwei-Jay Lin is an academic researcher from University of California, Irvine. The author has contributed to research in topics: Service-oriented architecture & Scheduling (computing). The author has an hindex of 36, co-authored 159 publications receiving 7128 citations. Previous affiliations of Kwei-Jay Lin include IBM & National Taiwan University.


Papers
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Journal ArticleDOI
TL;DR: A broker-based architecture is designed to facilitate the selection of QoS-based services and efficient heuristic algorithms for service processes of different composition structures are presented.
Abstract: Service-Oriented Architecture (SOA) provides a flexible framework for service composition Using standard-based protocols (such as SOAP and WSDL), composite services can be constructed by integrating atomic services developed independently Algorithms are needed to select service components with various QoS levels according to some application-dependent performance requirements We design a broker-based architecture to facilitate the selection of QoS-based services The objective of service selection is to maximize an application-specific utility function under the end-to-end QoS constraints The problem is modeled in two ways: the combinatorial model and the graph model The combinatorial model defines the problem as a multidimension multichoice 0-1 knapsack problem (MMKP) The graph model defines the problem as a multiconstraint optimal path (MCOP) problem Efficient heuristic algorithms for service processes of different composition structures are presented in this article and their performances are studied by simulations We also compare the pros and cons between the two models

1,225 citations

Journal ArticleDOI
TL;DR: A queuing-theoretical formulation of the imprecise scheduling problem is presented and workload models that quantify the tradeoff between result quality and computation time are reviewed.
Abstract: The imprecise computation technique, which prevents timing faults and achieves graceful degradation by giving the user an approximate result of acceptable quality whenever the system cannot produce the exact result in time, is considered. Different approaches for scheduling imprecise computations in hard real-time environments are discussed. Workload models that quantify the tradeoff between result quality and computation time are reviewed. Scheduling algorithms that exploit this tradeoff are described. These include algorithms for scheduling to minimize total error, scheduling periodic jobs, and scheduling parallelizable tasks. A queuing-theoretical formulation of the imprecise scheduling problem is presented. >

582 citations

Journal ArticleDOI
Jen-Yao Chung1, J.W.S. Liu1, Kwei-Jay Lin1
TL;DR: Two workload models of imprecise computations are presented, which differ from traditional models in that a task may be terminated any time after it has produced an acceptable result.
Abstract: The problem of scheduling periodic jobs in hard real-time systems that support imprecise computations is discussed. Timing faults are avoided in such systems by making available intermediate, imprecise results of acceptable quality when results of the desired quality cannot be produced on time. Two workload models of imprecise computations are presented. These models differ from traditional models in that a task may be terminated any time after it has produced an acceptable result. Each task is logically decomposed into a mandatory part followed by an optional part. In a feasible schedule, the mandatory part of every task is completed before the deadline of the task. The optional part refines the result produced by the mandatory part to reduce the error in the result. >

286 citations

Journal ArticleDOI
TL;DR: This paper studies the end-to-end QoS issues of composite services by utilizing a QoS broker that is responsible for selecting and coordinating the individual service component, and proposes two solution approaches to the service selection problem: the combinatorial approach, by modeling the problem as the Multiple Choice Knapsack Problem (MCKP), and the graph approach, as the constrained shortest path problem in the graph theory.
Abstract: Web services are new forms of Internet software that can be universally deployed and invoked using standard protocols. Services from different providers can be integrated into a composite service regardless of their locations, platforms, and/or execution speeds to implement complex business processes and transactions. In this paper, we study the end-to-end QoS issues of composite services by utilizing a QoS broker that is responsible for selecting and coordinating the individual service component. We design the service selection algorithms used by QoS brokers to construct the optimal composite service. The objective of the algorithms is to maximize the user-defined utility function value while meeting the end-to-end delay constraint. We propose two solution approaches to the service selection problem: the combinatorial approach, by modeling the problem as the Multiple Choice Knapsack Problem (MCKP), and the graph approach, by modeling the problem as the constrained shortest path problem in the graph theory. We study efficient solutions for each approach.

277 citations

01 Jan 1994
TL;DR: An imprecise mechanism for the generation and use of approximate results can be integrated in a natural way with a traditional fault-tolerance mechanism.
Abstract: The imprecise computation technique has been proposed as a way to handle transient overload and to enhance fault tolerance of real-time systems. In a system based on this technique, each time-critical task is designed in such a way that it can produce a usable, approximate result in time whenever a failure or overload prevents it from producing the desired, precise result. This paper describes ways to implement imprecise computations, models to characterize them and algorithms for scheduling them. An imprecise mechanism for the generation and use of approximate results can be integrated in a natural way with a traditional fault-tolerance mechanism. An architectural framework for this integration is described. >

277 citations


Cited by
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Journal ArticleDOI
TL;DR: A survey of the different security risks that pose a threat to the cloud is presented and a new model targeting at improving features of an existing model must not risk or threaten other important features of the current model.

2,511 citations

Proceedings ArticleDOI
05 Dec 1989
TL;DR: An exact characterization of the ability of the rate monotonic scheduling algorithm to meet the deadlines of a periodic task set and a stochastic analysis which gives the probability distribution of the breakdown utilization of randomly generated task sets are represented.
Abstract: An exact characterization of the ability of the rate monotonic scheduling algorithm to meet the deadlines of a periodic task set is represented. In addition, a stochastic analysis which gives the probability distribution of the breakdown utilization of randomly generated task sets is presented. It is shown that as the task set size increases, the task computation times become of little importance, and the breakdown utilization converges to a constant determined by the task periods. For uniformly distributed tasks, a breakdown utilization of 88% is a reasonable characterization. A case is shown in which the average-case breakdown utilization reaches the worst-case lower bound of C.L. Liu and J.W. Layland (1973). >

1,582 citations

Journal ArticleDOI
TL;DR: A broker-based architecture is designed to facilitate the selection of QoS-based services and efficient heuristic algorithms for service processes of different composition structures are presented.
Abstract: Service-Oriented Architecture (SOA) provides a flexible framework for service composition Using standard-based protocols (such as SOAP and WSDL), composite services can be constructed by integrating atomic services developed independently Algorithms are needed to select service components with various QoS levels according to some application-dependent performance requirements We design a broker-based architecture to facilitate the selection of QoS-based services The objective of service selection is to maximize an application-specific utility function under the end-to-end QoS constraints The problem is modeled in two ways: the combinatorial model and the graph model The combinatorial model defines the problem as a multidimension multichoice 0-1 knapsack problem (MMKP) The graph model defines the problem as a multiconstraint optimal path (MCOP) problem Efficient heuristic algorithms for service processes of different composition structures are presented in this article and their performances are studied by simulations We also compare the pros and cons between the two models

1,225 citations

Book
15 Jan 2000
TL;DR: RTSJ's features and the thinking behind the specification's design are explained, which aims to provide a platform-a Java execution environment and application program interface (API) that lets programmers correctly reason about the temporal behavior of executing software.
Abstract: New languages, programming disciplines, operating systems, and software engineering techniques sometimes hold considerable potential for real-time software developers. A promising area of interest-but one fairly new to the real-time community-is object-oriented programming. Java, for example, draws heavily from object orientation and is highly suitable for extension to real-time and embedded systems. Recognizing this fit between Java and real-time software development, the Real-Time for Java Experts Group (RTJEG) began developing the real-time specification for Java (RTSJ) in March 1999 under the Java Community Process. This article explains RTSJ's features and the thinking behind the specification's design. The goal of the RTJEG, of which the authors are both members, was to provide a platform-a Java execution environment and application program interface (API)-that lets programmers correctly reason about the temporal behavior of executing software.

1,094 citations