Scheduling is essential in peer-to-peer (P2P) video-on-demand (VoD) applications to obtain desirable user experience and high sharing efficiency. Existing systems and proposals largely utilize scheduling mechanisms th...
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Scheduling is essential in peer-to-peer (P2P) video-on-demand (VoD) applications to obtain desirable user experience and high sharing efficiency. Existing systems and proposals largely utilize scheduling mechanisms that are periodical in nature. We refer these as time-driven scheduling. In this paper we argue that the time-driven scheduling algorithm is not efficient for P2P VoD due to its inadequate resource utilization and inability in quickly adapting to the potential dynamics in such systems. We propose an event-driven scheduling algorithm for P2P VoD systems, in which the scheduler is triggered by events such as peer churn or/and random seeks. We evaluate our design through extensive simulations, and the experimental results show that event-driven scheduling outperforms time-driven scheduling in terms of both user experience and system scalability.
In grid and cloud computing infrastructures, the integrity of a computing platform is a critical security requirement in order to provide secure and honest computing environments to service providers and resource cons...
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In grid and cloud computing infrastructures, the integrity of a computing platform is a critical security requirement in order to provide secure and honest computing environments to service providers and resource consumers. However, due to the fact that software components running on a single platform are usually provided and maintained by different authorities which are potentially untrusted to each other, the problem to monitor and protect runtime system integrity become very challenging and has not been well addressed yet. In this paper, we present a virtualization based dynamic integrity protection method which ensures that only appropriate authorities can control over their components without interfering with other component providers or authorities. In our solution, integrity requirements defined by the authorities of upper components (e.g., service middleware and applications) are respected by preventing the underlying components (e.g., operating system) from exposing their sensitive data, which can be caused by update of the underlying components or other malicious actions. We implement our solution on Xen-based platform, and our evaluation results show that the solution is effective for integrity protection with acceptable performance overhead.
The semantic gap is a big challenge in image retrieval area. Previous studies in web image retrieval have mainly focused on Relevance feedback (RF) and Latent semantic indexing (LSI) to alleviate the gap. This paper p...
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The semantic gap is a big challenge in image retrieval area. Previous studies in web image retrieval have mainly focused on Relevance feedback (RF) and Latent semantic indexing (LSI) to alleviate the gap. This paper proposes an approach base on Frequent itemset mining (FIM) and Association rule (AR) techniques, which explores the semantic association rule between the two modalities that are represented by keyword and visual feature clusters. The rules are obtained offline based on the inverted file, and utilized in query process online to realize the integration of the two modalities of web images. Our approach improves the retrieval performance and is scalable well, as well as satisfies the requirement of the web users with no additional interactions. The experiments are carried out in our web image retrieval system named VAST (VisuAl & SemanTic image search), and the results show the effectiveness of the proposed approach.
A large-scale image retrieval system for the WWW, named VAST (VisuAl & SemanTic image search), is presented in this paper. Based on the existing inverted file and visual feature clusters, we form a semantic networ...
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ISBN:
(纸本)9788955191356
A large-scale image retrieval system for the WWW, named VAST (VisuAl & SemanTic image search), is presented in this paper. Based on the existing inverted file and visual feature clusters, we form a semantic network on top of the keyword association on the visual feature clusters. The system is able to automatically combine keyword and visual features for retrieval by the semantic network The combination is automatic, simple, and very fast, which is suitable for large-scale web dataset Meanwhile, the retrieval takes advantage of the semantic contents of the images in addition to the low-level features, which remarkably improves the retrieval precision. The experimental results demonstrate the superiority of the system.
Current grid information service is centralized or hierarchical and proves inefficient as grid scale rapidly increases. The introduction of P2P techniques into grids breaks an encouraging path. However, frequent join ...
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ISBN:
(纸本)9781605580777
Current grid information service is centralized or hierarchical and proves inefficient as grid scale rapidly increases. The introduction of P2P techniques into grids breaks an encouraging path. However, frequent join and departure of resource nodes require strong self-organization capacity of system to maintain their rigid structure. Moreover, arranging identifier space for P2P nodes is knotty and has great impact on system performance. If the identifier space is too large, some nodes will be overloaded. On the contraiy, small identifier space will bring the same problem as millennium bug. To address the issues, this paper proposes a scalable DHT-based (Distributed Hash Table) Information Service (DIS) for gridsystem, which organizes grid resources into a DHT ring based on VO (Virtual Organization). To save the identifier space while retaining the scalability and system performance, only stable VOs can join DIS via a new DHT node, whereas volatile VOs join DIS through being the sub-domain of other VO. Experimental results show that DIS provides rapid resource query, strong scalability and high throughput, meanwhile avoiding the key node failure as well as the bottleneck problem. Copyright 2008 ACM.
Peer-to-peer (P2P) has become an important computing model because of its adaptation, selforganization and autonomy. But how to organize dynamic nodes in P2P networks efficiently for gaming message passing services is...
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Peers in multiple P2P applications execute overlapped operations with different implementation, like neighbour management, resource publish/lookup, delay investigation, which leads to poor interoperability and unneces...
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With the development of semantic Web, search efficiency is becoming a challenging issue. To address this problem, we design an approach which mainly has two features. First, we explore potential semantic relationship ...
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With the development of semantic Web, search efficiency is becoming a challenging issue. To address this problem, we design an approach which mainly has two features. First, we explore potential semantic relationship between different objects and make full use of them to build a semantic buffer on server end, enhancing search speed. Second, we put another relatively small semantic buffer on each client so as to adapt to each individual user's interests, further improving the whole search efficiency and reducing server's load. Through testing on a practical platform, we testified that this semantic double-buffer based search approach can not only effectively reduce user's request response time, but considerably release server's load, bringing a high scalability.
Many grid middleware such as Globus Toolkit and GPE have started to support virtual machines. They implement the remote control of virtual machine by grid service and make use of virtual machinespsila function of quic...
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ISBN:
(纸本)9781424425129
Many grid middleware such as Globus Toolkit and GPE have started to support virtual machines. They implement the remote control of virtual machine by grid service and make use of virtual machinespsila function of quick deployment to construct the execution environment of grid application fast. In order to support virtual machine in grid environment, VMgrid (Virtual Machine grid) is presented. All services in VMgrid are implemented based on secure shell host protocol (SSH) while Globus Toolkitpsilas Virtual Workspace is on WSRF. This paper gives a clear description of VMgrid. Some comparisons with Globus Toolkitpsilas Virtual Workspace in performance are made in this paper. Performance results show that VMgrid virtual workspace atomic services are more effective than that of Globus.
Heterogeneous grid workflow management plays an important role in the grid interoperation. It integrates service resources from different gridsystems and packs them as atomic services into a composite service. The fo...
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ISBN:
(纸本)9781424432806;9780769534497
Heterogeneous grid workflow management plays an important role in the grid interoperation. It integrates service resources from different gridsystems and packs them as atomic services into a composite service. The focuses of the research are how to shield the difference among the heterogeneous gridservices and how to provide a flexible way to compose services. Heterogeneous grid workflow management mechanism, based on virtual service, compiles with BPEL4WS standards and shields the differences in the aspects of both organization of service information and the types of service among heterogeneous grids. The mechanism compensates for the weakness that traditional mechanism requires prior static binding in the service selection and scheduling. The proposed mechanism can provide some new functions like service backup and dynamic service selection based on QoS to improve the flexibility and stability of workflow management. In addition, in order to address the issues of tight coupling between data and service, the proposed mechanism employs virtual data space and corresponding data transferring solution.
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