This paper describes an approach for developing distributed applications that help deal with rapidly changing situations such as terrorist attacks, hurricanes and supply chain disruptions. Important characteristics of...
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ISBN:
(纸本)088986392X
This paper describes an approach for developing distributed applications that help deal with rapidly changing situations such as terrorist attacks, hurricanes and supply chain disruptions. Important characteristics of such applications are that they must handle unexpected events and that they are often modified on-the-fly, by multiple people who may belong to different organizations, to deal with changing situations. Abstract and concrete models for specifying, reasoning about, and implementing such systems are presented. In the abstract model, an application is a set of state transition rules over the global state of a distributed system. In the concrete model, an application is a set of message-driven processes and each computation is a sequence of atomic operations in which a process receives a message, changes its state, and sends messages. An implementation of the concrete model using XML as the message and state format, with state transitions specified using XSLT, is briefly described. A key feature of this implementation is that messages and process states are represented using a format that allows applications to be easily observed and modified during their execution.
Moores law has meant that most households in the west countries own at least two perfectly functional computers. At the same time personal area networks are beginning to emerge, linking up mobile phones, PDAs,mp3/ogg,...
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ISBN:
(纸本)088986392X
Moores law has meant that most households in the west countries own at least two perfectly functional computers. At the same time personal area networks are beginning to emerge, linking up mobile phones, PDAs,mp3/ogg, Vobis players, etc. These two types of small, local, single owner/administrator networks need an appropriate model of functionality and management to provide the users with the highest degree of functionality. This paper describes an effort to create a heterogamous-networked system using Java and t JXTA project, model witch is based on clusters and grids concepts. The main function of the system is to allow central control of all peers from any peer and sharing of data resource. Another requirement is robustness and resilience to peer failure. The implementation and the test carried proved that a grid type model for home networking is a valid model.
Traditionally, workload distribution methods for software distributed shared memory systems (DSM) have only considered CPU resource. However, memory resource is also an important consideration for workload distributio...
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ISBN:
(纸本)088986392X
Traditionally, workload distribution methods for software distributed shared memory systems (DSM) have only considered CPU resource. However, memory resource is also an important consideration for workload distribution. If a processor cannot afford sufficient physical memory space to cache the data required by its assigned threads, it must carry out page replacements during their execution. This delays thread execution, which in turn increases the overall execution time of the user program. This paper proposes a new workload distribution method for DSM systems, which considers both CPU resources and memory resources. The experimental results shows that the proposed method is more effective in minimizing the execution time of applications than methods considering only CPU or memory resources.
One of the key issues in the design of scalable and cost-effective distributed Virtual Environment (DVE) systems is the partitioning problem. This problem consists of efficiently assigning clients (3-D avatars) to the...
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ISBN:
(纸本)088986392X
One of the key issues in the design of scalable and cost-effective distributed Virtual Environment (DVE) systems is the partitioning problem. This problem consists of efficiently assigning clients (3-D avatars) to the servers in the system, and some methods have been already proposed for solving it. However, only one of these methods takes into account the non-linear behavior of DVE servers with the number of avatars they support, and this method uses a load balancing technique of local scope. As a result, it only provides good performance if the movement pattern of avatars is uniform. In this paper, we propose an adaptive load balancing technique of global scope for solving the partitioning problem in DVE systems. The global scope of the proposed technique allows to avoid DVE saturation as long as possible. Evaluation results show that the proposed strategy can improve DVE system performance, regardless of both the movement patterns of avatars and also the initial distribution of avatars in the virtual world.
The main goal of global computing system is to harvest the idle time of computers connected to Internet for building a virtual large supercomputer. While most previous systems follow centralized model, we proposes new...
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ISBN:
(纸本)088986392X
The main goal of global computing system is to harvest the idle time of computers connected to Internet for building a virtual large supercomputer. While most previous systems follow centralized model, we proposes new fully decentralized global computing system using Peer-to-Peer (P2P) network. Two core goals of our system are to improve the scalability of system and the reusability of computation program. As the role of a broker of previous systems is shifted to peers in P2P network, there is no need of central server leading to scalability improvement. In addition, providing new service structure separating task management and actual computation, both new and legacy computation program can be easily adapted to our system resulting in reusability improvement. We implemented our system on JXTA P2P technology and also developed three applications running on our system to prove the usefulness of our system. Experimental results showed the improvement of performance.
In this paper we study the handover failure probability and present a call admission control scheme considering the call level quality of service (QoS) in LEO satellite networks. QoS provisioning of low handover failu...
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ISBN:
(纸本)088986392X
In this paper we study the handover failure probability and present a call admission control scheme considering the call level quality of service (QoS) in LEO satellite networks. QoS provisioning of low handover failure probability is used in the proposed call admission control (CAC) scheme to guarantee predefined QoS level of call dropping probability for each calls. To ensure the call dropping probability we formulate the handover failure probability using the classification of the local traffic conditions and the derivation of generation probability for the equivalent case of handover failure event. The performance of the proposed scheme has been evaluated in terms of call dropping probability and handover failure probability. The performance evaluation results have clearly shown that the proposed CAC scheme guarantees the continuity of call connections with predefined QoS levels.
In this paper, we present a mechanism able to predict the performance a given workload will achieve when running on a given storage device. This mechanism is composed by two modules. The first one is able to learn the...
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ISBN:
(纸本)088986392X
In this paper, we present a mechanism able to predict the performance a given workload will achieve when running on a given storage device. This mechanism is composed by two modules. The first one is able to learn the behavior of a workload in order to be able to reproduce its behavior later on, without a new execution, even when the storage drives or data placement are modified. The second module is a drive modeler that is able to learn how a storage drive works in an automatic way, just executing some synthetic tests. Once we have the workload and drive models, we can predict how well the application will perform on the selected storage device or devices or when the data placement is modified. The results presented in this paper will show that this prediction system achieves errors below 10% when compared to the real performance obtained. It is important to notice that the two modules will treat both the application and the storage device as black boxes and will need no previous information about them.
In this paper a new approach to design a reconfigurable mesh architecture is presented. This method uses a single-stage interconnection network which can implement various arrangement to a mesh topology in synchronous...
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ISBN:
(纸本)088986392X
In this paper a new approach to design a reconfigurable mesh architecture is presented. This method uses a single-stage interconnection network which can implement various arrangement to a mesh topology in synchronous mode and very high speed communication between two nodes in asynchronous mode. The contribution of paper is using the switching boxes to connection nodes as an interconnection network. The novelty of paper is proper and parallel connection of boxes and design of special code set which easily configures the network. The technical aspect of paper is its simple controller that can switch interconnection network properly. The main features of the presented architecture are: arrange high variety, few stage and low delay, simple switching mechanism, simple self routing, low propagation delay time and finally minimum diameter. To show the merit of the proposed architecture, a sort algorithm with this structure is presented.
In this paper we consider a finite element algorithm solving the three dimensional Navier-Stokes equation using the method of characteristics. The algorithm is based on a splitting scheme using a characteristic pressu...
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ISBN:
(纸本)088986392X
In this paper we consider a finite element algorithm solving the three dimensional Navier-Stokes equation using the method of characteristics. The algorithm is based on a splitting scheme using a characteristic pressure correction method. It's well known, that the most expensive part of the characteristic integration scheme consists of the search for the volume that contains the foot of a given characteristic. The present paper considers different techniques for solving this problem and presents a new, efficient formulation of a search algorithm. This algorithm has been implemented based on the parallel data structure provided by the finite element framework padfem2. We present the results that we have obtained applying this algorithm to two well studied flow problems. Furthermore, we show the efficiency of the splitting scheme computed on a massive parallel cluster system.
The Simple Object Access Protocol (SOAP) is an emerging technology in the field of web services. Web services demand high performance, security and extensibility. SOAP, being based on Extensible Markup Language (XML),...
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ISBN:
(纸本)088986392X
The Simple Object Access Protocol (SOAP) is an emerging technology in the field of web services. Web services demand high performance, security and extensibility. SOAP, being based on Extensible Markup Language (XML), inherits not only the advantages of XML, but its relatively poor performance. This makes SOAP a poor choice for many high-performance web services. In this paper, we analyze the client side processing of a SOAP request and investigate the stages of this processing, where SOAP lags behind its peers in speed. We concentrate on the more popular RPC-style implementation of SOAP rather than the message-style. We then present an optimized design utilizing a caching mechanism at the client side for SOAP messages. We also describe our implementation based on the Apache Java SOAP client, which gives dramatically better performance (800%) over the original code.
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