Visualization of remote data needs software that is fundamentally designed for distributed processing and high-speed networks. Motivated by and following the requirements of a distributed visualization application, th...
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Visualization of remote data needs software that is fundamentally designed for distributed processing and high-speed networks. Motivated by and following the requirements of a distributed visualization application, this article describes the design and implementation of a fast and configurable remote data access system called eavivdata. Because wide-area networks may have a high latency, the remote data access system uses an architecture that effectively hides latency. Four remote data access architectures are analyzed and the results show that an architecture that combines bulk and pipeline processing is the best solution for high-throughput remote data access. the resulting system, also supporting high-speed transport protocols and configurable remote operations, is up to 400 times faster than a comparable existing remote data access system.
Deploying the sensor nodes at the best locations for random field reconstruction via sensor network is a fundamental task. One-dimensional random field is a stochastic process. In this paper, we first propose an optim...
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Deploying the sensor nodes at the best locations for random field reconstruction via sensor network is a fundamental task. One-dimensional random field is a stochastic process. In this paper, we first propose an optimal sensor deployment strategy for Wiener process estimation. the optimal locations for the deployed sensors are uniformly distributed in the field. In addition, we propose a suboptimal sensor deployment to estimate the Gaussian random field which is described as an Ornstein-Uhlenbeck process. We show that the suboptimal deployment strategy for Gaussian random field is also uniformly distributed. Several simulations show the performance of our proposed deployment strategies.
Service level agreements are an intrinsic part of service level management frameworks. they are electronic contracts, or part of a contract, and capture quality-of-service guarantees, responsibilities and constraints ...
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Service level agreements are an intrinsic part of service level management frameworks. they are electronic contracts, or part of a contract, and capture quality-of-service guarantees, responsibilities and constraints related to the provision and consumption of services. In the area of distributed systems a handful of service level agreement specifications exist, designed to support the automated management of service-related agreements. Each of these specifications has a different focus and targets a different group of usage scenarios and stakeholders. In this paper, we show, based on the example of the WS-Agreement specification, how to make use of SLA@SOI's service level agreement model SLA* to map between different service level agreement representations and thus be able to integrate a variety of different specifications into one service-oriented infrastructure.
Versatile storage systems aim to maximize storage resource utilization by supporting the ability to `morph' the storage system to best match the application's demands. To this end, versatile storage systems si...
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Versatile storage systems aim to maximize storage resource utilization by supporting the ability to `morph' the storage system to best match the application's demands. To this end, versatile storage systems significantly extend the deployment- or run-time configurability of the storage system. this flexibility, however, introduces a new problem: a much larger, and potentially dynamic, configuration space makes manually configuring the storage system an undesirable if not unfeasible task. this paper presents our initial progress towards answering the question: “How can we configure a distributed storage system (i.e., enable/disable its various optimizations and configure their parameters) with minimal human intervention?” We discuss why manually configuring the storage system is undesirable; present the success criteria for an automated configuration solution; propose a generic architecture that supports automated configuration; and, finally, instantiate this architecture into a first prototype, which controls the configuration of similarity detection optimizations in the MosaStore distributed storage system. Our evaluation results demonstrate that the prototype can provide performance close to the optimal configuration at the cost of minimal overhead.
Snapshot isolation (SI) is an important database transactional isolation level adopted by major database management systems (DBMS). Until now, there is no solution for any traditional DBMS to be easily replicated with...
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Snapshot isolation (SI) is an important database transactional isolation level adopted by major database management systems (DBMS). Until now, there is no solution for any traditional DBMS to be easily replicated with global SI for distributed transactions in cloud computing environments. HBase is a column-oriented data store for Hadoop that has been proven to scale and perform well on clouds. HBase features random access performance on par with open source DBMS such as MySQL. However, HBase only provides single atomic row writes based on row locks and very limited transactional support. In this paper, we show how multi-row distributed transactions with global SI guarantee can be easily supported by using bare-bones HBase with its default configuration so that the high throughput, scalability, fault tolerance, access transparency and easy deployability properties of HBase can be inherited. through performance studies, we quantify the cost of adopting our technique. the contribution of this paper is that we provide a novel approach to use HBase as a cloud database solution with global SI at low added cost. Our approach can be easily extended to other column-oriented data stores.
Performance assurance has become an important aspect in grid and cloud computing which provide services over the Internet, and Service Level Agreements (SLA) are frequently contracted between users and the service pro...
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Performance assurance has become an important aspect in grid and cloud computing which provide services over the Internet, and Service Level Agreements (SLA) are frequently contracted between users and the service providers. However, the I/O performance of the storage or data access service is still provided on a best effort basis. Some distributed storage systems implement performance reservation, but the reservation is implemented inside of the storage and works in an adaptive manner. In order to promise performance guarantees to users, we propose a distributed storage system allowing application users to explicitly make an advanced and time-based reservation for I/O access and storage space. thus the requested performance is guaranteed during the reserved time. this paper describes our proposed concept and the design architecture of the storage system, including the reservation interface, resource management and I/O control frameworks. then it explains our prototype which implements a simple resource allocation strategy and I/O control of the storage network along the design. the experiment results using the prototype are also shown. they indicate that the reservation cost entailed only a low performance impact on users, and that the requested performance was achieved by the reservation feature.
Security engineering must be integrated with all stages of application specification and development to be effective. Doing this properly is increasingly critical as organisations rush to offload their software servic...
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ISBN:
(纸本)9783642169540
Security engineering must be integrated with all stages of application specification and development to be effective. Doing this properly is increasingly critical as organisations rush to offload their software services to cloud providers. Service-level agreements (SLAs) withthese providers currently focus on performance-oriented parameters, which runs the risk of exacerbating an impedance mismatch withthe security middleware. Not only do we want cloud providers to isolate each of their clients from others, we also want to have means to isolate components and users within each client's application. We propose a principled approach to designing and deploying end-to-end secure, distributed software by means of thorough, relentless tagging of the security meaning of data, analogous to what is already done for data types. the aim is to guarantee that-above a small trusted code base-data cannot be leaked by buggy or malicious software components. this is crucial for cloud infrastructures, in which the stored data and hosted services all have different owners whose interests are not aligned (and may even be in competition). We have developed data tagging schemes and enforcement techniques that can help form the aforementioned trusted code base. Our big idea-cloud-hosted services that have end-to-end information flow control-preempts worries about security and privacy violations retarding the evolution of large-scale cloud computing.
Compared with deterministic stability assessment, probabilistic assessment can provide a more comprehensive, rational and realistic measure of system stability level and thus a deeper insight into system stability pro...
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Compared with deterministic stability assessment, probabilistic assessment can provide a more comprehensive, rational and realistic measure of system stability level and thus a deeper insight into system stability problem. However, considerable computational effort will be required to gain a reliable assessment for probabilistic analysis. this paper presents a method based on the distributed DSATools ™ to speed up the computation required. Also two instability probability indices are defined as indicators of the overall system stability level and the severity of individual component fault. the proposed method and indices are implemented on a small scale distributed computation platform consisting of 1 client and 2 servers. Simulations on the IEEE 17-machine 162-bus system have verified the feasibility of the proposed method and indices to large scale probabilistic transient stability assessment.
Previous distributed anomaly detection efforts have operated on summary statistics gathered from each node. this has the advantage that the audit trail is limited in size since event sets can be succinctly represented...
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Previous distributed anomaly detection efforts have operated on summary statistics gathered from each node. this has the advantage that the audit trail is limited in size since event sets can be succinctly represented. While this minimizes the bandwidth consumed and helps scale the detection to a large number of nodes, it limits the infrastructure's ability to identify the source of anomalies. We describe three optimizations that together allow fine-grained tracking of the sources of anomalous activity in a Grid, thereby facilitating precise responses. We demonstrate the scheme's scalability in terms of storage and network bandwidth overhead with an implementation on nodes running BOINC. the results generalize to other types of Grids as well.
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