Virtual machine (VM) based logging-and-replay technology has attracted much attention for system security, fault tolerance, and debugging. However, so far there is not a replay system designed on virtual machine monit...
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Virtual machine (VM) based logging-and-replay technology has attracted much attention for system security, fault tolerance, and debugging. However, so far there is not a replay system designed on virtual machine monitor Xen. In this paper, XenLR presents the design and implementation of a logging tool for full system replay on Xen. To reduce the design complexity, XenLR is achieved on a lightweight VM mini OS. Our preliminary work dedicates to identify architectural non-deterministic events and record them compactly. XenLR does not modify the guest OS and only need to record the external inputs (keyboard input and time update on mini OS). The log data are saved in the privileged domain¿s file system through transmission channels. The experiments indicate that XenLR results in low time and space overhead. Overhead due to logging is imperceptible for interactive use. The log files grow at 1.4 MByte/day, so it causes litter space consumption for today¿s large capacity disk storage.
This paper describes a method using gridtechnology to improve traffic algorithm efficiency. The method cooperates traffic status estimation algorithm with gridtechnology. It collects and preprocesses massive real-ti...
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This paper describes a method using gridtechnology to improve traffic algorithm efficiency. The method cooperates traffic status estimation algorithm with gridtechnology. It collects and preprocesses massive real-time data of taxi global positioning system (GPS) as floating car data as well as geographic Information systems (GIS) data of Shanghai urban road network. Then, it adopts gridtechnology to deal with computation for the shortest time path algorithm on traffic status estimation in real time. The results of experiment prove that the gridtechnology can greatly improve the computing efficiency of traffic status estimation model.
Traversing network address translation (NAT) for peer-to-peer (P2P) communication has become a hot topic recently. Compared to UDP, establishing TCP connections for hosts behind different NATs is more complex. Thus, m...
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Traversing network address translation (NAT) for peer-to-peer (P2P) communication has become a hot topic recently. Compared to UDP, establishing TCP connections for hosts behind different NATs is more complex. Thus, many TCP-based applications do not address TCP traversal through NATs. Some solutions suggest using delegates to relay all communications, or tunneling TCP over UDP. However, they require a big reform to network architecture, or using a nonstandard TCP/IP stack. In this paper, we present a novel idea called TCPBridge. TCPBridge converts TCP traversal to UDP traversal without modifying any binaries of the TCP-based applications. Our design can be integrated with those P2P applications which have not solved TCP traversal problem, and extends them to support direct communications between NAT hosts. It deals with the problem of TCP traversal, so as to improve the usability of applications. We have implemented TCPBridge in several existing P2P systems. Statistics prove that TCPBridge is scalable and robust, and we believe it will benefit many other existing P2P applications.
The research about the interaction between grid environments and users is becoming popular. Many scientists propose the integration for Web 2.0 technologies and gridcomputing. In this paper, we propose a flexible Web...
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The research about the interaction between grid environments and users is becoming popular. Many scientists propose the integration for Web 2.0 technologies and gridcomputing. In this paper, we propose a flexible Web-based framework for grid applications - WAGA, which tries to bridge the gap between grid middleware and grid applications. WAGA provides a WYSIWYG (what you see is what you get) way for the programming for grid applications by adopting participation, interaction and sharing features of Web 2.0 technology. With WAGA, a grid user is able to use the grid resources and to develop grid applications without understanding the underlying complexity of grids. WAGA is composed with a Web GUI (called WAGA-designer) and someWeb-based APIs. WAGA-designer is used by grid users to develop application-based Web portal, and the WebAPIs are used by the WAGA-designer. The use case study shows that WAGA is flexible for grid users, and the performance evaluation shows that WAGA works with high efficiency.
This article consists of a collection of slides from the author's conference presentation. It is concluded that unrealistic targets are endemic to a highly visible project managed by executives disconnected from t...
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This article consists of a collection of slides from the author's conference presentation. It is concluded that unrealistic targets are endemic to a highly visible project managed by executives disconnected from the engineers doing the real work.
This paper proposes a novel parallel data transfer mechanism to improve the performance of data transfer in grid environment. It utilizes the servers distributed in gridsystem and selects some of them as the proxy se...
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This paper proposes a novel parallel data transfer mechanism to improve the performance of data transfer in grid environment. It utilizes the servers distributed in gridsystem and selects some of them as the proxy servers. It introduces the method of how to select the proxy server. Then data are divided into several parts and sent through the selected proxy servers with different physical links. By that, it can effectively improve the performance of data transfer.
In traditional grid, grid user can not validate whether grid service registered in grid platform can execute correctly or not because the system does not provide the measurement mechanism for grid service. In order to...
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In traditional grid, grid user can not validate whether grid service registered in grid platform can execute correctly or not because the system does not provide the measurement mechanism for grid service. In order to solve this problem, we propose a series of strategies and methods for trusted grid. These strategies and methods include: an access control policy for reference database, an integrity attestation for reference datasheet, a construction method of reference datasheet, a trusted storage algorithm of reference datasheet and a report algorithm of reference datasheet. All these constitute the measurement mechanism of service for trusted grid. Some experiments are done in order to validate the feasibility and the availability of this mechanism. The results show that it is feasible and efficient to validate whether grid service registered in trusted grid platform can execute correctly or not.
Text categorization is the process of assigning documents to a set of previously fixed categories. It is widely used in many data-oriented management applications. Many popular algorithms for text categorization have ...
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ISBN:
(纸本)9780769533162
Text categorization is the process of assigning documents to a set of previously fixed categories. It is widely used in many data-oriented management applications. Many popular algorithms for text categorization have been proposed, such as Naive Bayes, k-Nearest Neighbor (k-NN), Support Vector Machine (SVM). However, those classification approaches do not perform well in every case, for example, SVM can not identify categories of documents correctly when the texts are in cross zones of multi-categories, k-NN cannot effectively solve the problem of overlapped categories borders. In this paper, we propose an approach named as Multi-class SVM-kNN (MSVM-kNN) which is the combination of SVM and k-NN. In the approach, SVM is first used to identify category borders, then k-NN classifies documents among borders. MSVM-kNN can overcome the shortcomings of SVM and k-NN and improve the performance of multi-class text classification. The experimental results show MSVM-kNN performs better than SVM or kNN.
In virtual machine (VM) systems, mandatory access control (MAC) enforcement is possible now. This technique is both stronger and more flexible than traditional VM isolation, even if network communication is controlled...
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In virtual machine (VM) systems, mandatory access control (MAC) enforcement is possible now. This technique is both stronger and more flexible than traditional VM isolation, even if network communication is controlled. Unfortunately all of the VM systems with the MAC enforcement does not consider that the MAC controls may be distorted by covert channels, which constitute an important risk in VM systems. Traditional MAC models have difficulties being enforced to reduce the risk of covert flows in VM systems due to the many constraints and the lack of flexibility. In this paper, we identify access control requirements for managing covert channels in VM systems through a critical analysis of the ways by which classical models constrain the covert information flows and we propose a model called the Prioritized Chinese Wall model (PCW) to reduce the risk of covert flows in VM systems while preserving the flexibility. Furthermore, we enforce the policy in sHype/Xen VM system.
The most important concept of a market is price – the terms on which the trading objects (products or services) are exchanged. In an ideal market, the price is a reflection of the current state of the market, and the...
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ISBN:
(纸本)9781424432806
The most important concept of a market is price – the terms on which the trading objects (products or services) are exchanged. In an ideal market, the price is a reflection of the current state of the market, and therefore it should be dynamic. From the seller perspective, using an effective dynamic pricing strategy can make a difference between making a profit or loss in a makret. In a grid marketplace, the strategy is even more important given it is very dynamic and volatile nature. In this paper, we describe and review three different pricing strategies for the grid market: Demand-Response, Revenue-Response and Price-Maximizing strategy, and analyze their behavior in different market conditions using simulation approach. Our results show that two of the strategies are able to generate high revenue in various market conditions.
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