Event-based communication is useful in many application domains, ranging from small centralised applications to large distributedsystems. Many different event models have been developed to address the requirements of...
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Event-based communication is useful in many application domains, ranging from small centralised applications to large distributedsystems. Many different event models have been developed to address the requirements of different application domains. One such model is the ECO (events, constraints, objects) model, which was designed to support distributed virtual world applications. Like many other event models, ECO has event-filtering capabilities that are meant to improve scalability by decreasing the network traffic in a distributed implementation. Our recent work in event-based systems has included building a fully-distributed version of the ECO model, including event-filtering capabilities. This paper describes the results of our evaluation of filters as a means of achieving increased scalability in the ECO model. The evaluation is empirical, and real data gathered from an actual event-based system is used. The findings show that: (i) filters are highly valuable in making distributed implementations of the model scale, (ii) multicasting contributes to the scalability and, perhaps most significantly, (iii) multicast groups can be dynamically generated from filters using local (per-node) knowledge rather than global knowledge of the distributed application.
The increased complexity of the service model relative to store-and-forward routers has made resource management one of the paramount concerns in active networking research and engineering. In this paper, we address t...
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An executing thread, in an object oriented programming language, is spawned, directly or indirectly, by a main process. This in turn gets its instructions from a primary class. In Java there is no close coupling of a ...
ISBN:
(纸本)9781581132069
An executing thread, in an object oriented programming language, is spawned, directly or indirectly, by a main process. This in turn gets its instructions from a primary class. In Java there is no close coupling of a thread and the objects from which they were created. The use of a container abstraction allows us to group threads and their respective objects into a single structure. A container that holds threads whose variables are all housed within the container is a perfect candidate for strong migration. To achieve this we propose a combination of three techniques to allow the containers to migrate in a manner that approaches strong mobility yet does not resort to retaining bindings to resources across distant and unreliable networks.
distributed application programmers rely on middleware such as CORBA in order to handle the complexity that arises from the distributed and heterogeneous nature of the underlying computing platform. CORBA, in particul...
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distributed application programmers rely on middleware such as CORBA in order to handle the complexity that arises from the distributed and heterogeneous nature of the underlying computing platform. CORBA, in particular, provides a media streaming mechanism that can be used both for media streaming and for associating QoS requirements with media streams. Despite defining the interfaces of the media streaming mechanism, the corresponding specification does not prescribe how QoS is enforced at low levels by the middleware. This paper describes the design and implementation of a QoS architecture, called Quartz, which has been integrated with CORBA in order to provide a framework that allows applications to transfer real-time media in open systems. This framework is employed to model and simulate a pattern recognition mechanism for use in an automated manufacturing cell, which is also described and analysed in this paper.
Proposes an application framework for mobile agents which provides rule-based generic services to support the three phases of a market transaction (information phase, contracting phase and settlement phase). It is des...
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Proposes an application framework for mobile agents which provides rule-based generic services to support the three phases of a market transaction (information phase, contracting phase and settlement phase). It is described within the four views of an electronic market (the business view, the transaction view, the services view and the infrastructure view) which describe organizational as well as technological aspects. The focus of this paper is on the technological aspects of the contracting phase in which the participating agents carry out an automated negotiation process to determine the terms of contract.
This paper describes an architecture that provides support for quality of service (QoS) specification and enforcement in heterogeneous distributed computing systems. The Quartz QoS architecture has been designed to ov...
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This paper describes an architecture that provides support for quality of service (QoS) specification and enforcement in heterogeneous distributed computing systems. The Quartz QoS architecture has been designed to overcome various limitations of previous QoS architectures that have constrained their use in heterogeneous systems. These limitations include dependencies on specific platforms and the fact that their functionality is often limited by design to one particular area of application. Quartz is able to accommodate differences among diverse computing platforms and areas of application by adopting a flexible and extensible platform-independent design, which allows its internal components to be rearranged dynamically in order to adapt the architecture to the surrounding environment. Further significant problems found in other QoS architectures, such as the lack of flexibility and expressiveness in the specification of QoS requirements and limited support for resource adaptation, are also addressed by Quartz. This paper describes the motivations for and design of Quartz in detail, presents a prototype implementation of Quartz and an analysis of its design based on experience with a number of applications that use this prototype.
An approach to implement strategies for automated negotiations in electronic commerce applications is presented. It is based on genetic algorithms (GAs) that evolve FSMs (finite state machines). Each of these FSMs rep...
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ISBN:
(纸本)0769506801
An approach to implement strategies for automated negotiations in electronic commerce applications is presented. It is based on genetic algorithms (GAs) that evolve FSMs (finite state machines). Each of these FSMs represents a negotiation strategy that competes against other strategies and is modified over time according to the outcome of this competition by using GA principles. The paper gives an overview of negotiating agents and work related to the paper. Then the application of genetic algorithms to FSMs is presented and relevant details on the implementation are given.
This paper presents a series of experiments that were conducted to investigate in the nonstationary behavior of a wafer fab after changes in product mix. The experiments were performed using a simulation model of the ...
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This paper presents a series of experiments that were conducted to investigate in the nonstationary behavior of a wafer fab after changes in product mix. The experiments were performed using a simulation model of the front end area of an existing semiconductor fab. We observe how short-term increases in wafer starts of a product influence the cycle time and WIP of this product and of the other products. It is examined how the fab recovers from such production surges under different dispatch rules. We also investigate how different lot start mechanisms affect the short term fab performance. More specifically, we observe the effects of changing the mix of the lots started into the fab on a weekly basis. Finally, we compare two alternative ways of releasing lots into the fab: the first is to distribute lot starts evenly over a given period, e.g. a week, and the other is to start all lots at the beginning of the period.
Our previous work in mobility support for CORBA applications resulted in the design and implementation of the Architecture for Location-Independent CORBA Environments (ALICE). The first version of ALICE enabled CORBA ...
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ISBN:
(纸本)078037133X
Our previous work in mobility support for CORBA applications resulted in the design and implementation of the Architecture for Location-Independent CORBA Environments (ALICE). The first version of ALICE enabled CORBA objects running on mobile devices to interact transparently with objects hosted by off-the-shelf CORBA implementations without relying on a centralised location register to keep track of their whereabouts. This paper presents the second version of ALICE on which work is ongoing. The improved architecture retains the features of the original and adds support for disconnected operation in the form of caching of server functionality on the client side. Furthermore, the architecture is being generalised beyond CORBA in order to make it applicable to other distribution infrastructures, such as Java RMI and DCOM.
作者：
Chris McDonaldKamran KazemiProgramming
Languages and Systems Group Department of Computer Science The University of Western Australia Nedlands Western Australia 6907
Parallel algorithms are often introduced to students by describing the geometric topologies formed by communicating processes and often the geographic relationships between them. However, the two most common message p...
ISBN:
(纸本)9781581132137
Parallel algorithms are often introduced to students by describing the geometric topologies formed by communicating processes and often the geographic relationships between them. However, the two most common message passing environments used in teaching, PVM and MPI, each provide only rudimentary support for the specification and execution of process topologies. There is a strong need for better syntactic and semantic support for process topologies in these environments, so that students may concentrate on the algorithms being studied, and not have to wrestle with the environments' infrastructure. This paper first motivates, and then describes the use of additional support within PVM and MPI which addresses this need.
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