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The performance of modern data-intensive applications is closely related to the speed of data access. However, a physical database optimization by design is often infeasible, due to the presence of large databases and time-varying workloads. In this paper we introduce a novel methodology for physical database optimization which allows for a quick and dynamic selection of indexes through the analysis...
Having discussed the transactional workflow wrong recovery properties and the transactional workflow control structure, the paper proposes the security workflow. When it comes to the security workflow, it is necessary to consider the compensation of the attack. In this paper, the danger recovery properties is introduced in security workflow: safe property, compensable property, retriable property,...
Web Security Gateway (WSG) is a new type of network security product that maintains the security of trusted networks. In this paper, a WSG model for evaluating WSG performance is presented. This paper advances discussion of previous studies on series services under multiple service windows. The proposed model consists of a two-stage queuing system. The first stage is a network layer simulation. The...
To address the challenges raised by the Internet usage evolution over the last years, the Content-Centric Networking (CCN) has been proposed. One key feature provided by CCN to improve the efficiency of content delivery is the in-network caching, which has major impact on the system performance. In order to improve caching effectiveness in such systems, studying the functioning of CCN in-network storage...
In an SDN/NFV-enabled network, the behavior of virtual switches is a major concern in determining the overall network performance. The prominent open-source solution for virtual switching is Open vSwitch while the DPDK library has been developed to accelerate the packet processing. In this paper, we develop a general framework for the modeling and the analysis of DPDK-based virtual switches, taking...
Various research work have highlighted the importance of modeling learner's personality to provide a personalized computer based learning. In particular, questionnaire is the most used method to model personality which can be long and not motivating. This makes learners unwilling to take it. Therefore, this paper refers to Learning Analytics (LA) to implicitly model learners' personalities based on...
The security protocol is proposed as a security solution for end-to-end communication between smart grid applications in the EU FP7 project C-DAX. Since the importance and widespread use of the security protocol, it is of great significance to formally analyze and verify relevant security properties of this security protocol. In this paper, we apply Communicating Sequential Processes (CSP) to model...
Datacenter networks are becoming crucial foundations for our information technology based society. However, commercial datacenter infrastructure is often unavailable to researchers for conducting experiments. In this work, we therefore elaborate on the possibility of combining commercial hardware and simulation to illustrate the scalability and performance of datacenter networks. We simulate a Datacenter...
End users of cloud applications range from novice to expert depending on how experienced they are in using them. With repeated usage of an application, a user's think time gradually decreases, known as human learning phenomenon. This decrease impacts the system workload thereby affecting the application's transient performance. However, such impact of human learning on system performance has never...
A multitude of issues affect the broader adoption of Cloud computing, with security arguably being amongst the most significant. To address security concerns, the process of threat analysis is advocated to assess potential attacks that can undermine the security goals. However, conducting threat analysis for the Cloud is a non-trivial task given the plethora of attack surfaces entailed in the multiple...
Due to increased government surveillance as well as data breaches, end-to-end encryption has recently received an increasing attention as a way to protect against such threats. End-to-end (E2E) encryption preserve the confidentiality of data on the wire as well as from service providers by performing encryption/decryption at clients keeping the keys strictly within client devices. There are many variants...
Climate Model Diagnostic Analyzer (CMDA) is a web-based information system designed for the climate modeling and model analysis community to analyze climate data from models and observations. CMDA provides tools to diagnostically analyze climate data for model validation and improvement, and to systematically manage analysis provenance for sharing results with other investigators. CMDA utilizes cloud...
Wimpy virtual instances equipped with small numbers of cores and RAM are popular public and private cloud offerings because of their low cost for hosting applications. The challenge is how to run latency-sensitive applications using such instances, which trade off performance for cost. In this study, we analytically and experimentally show that simultaneously scaling resources at coarse granularity...
Server consolidation is the hosting of multiple tenantson a server machine. Given a sequence of data analyticstenant loads defined by the amount of resources that thetenants require and a service-level agreement (SLA) between thecustomer and the cloud service provider, significant cost savingscan be achieved by consolidating multiple tenants. Since servermachines can fail causing their tenants to...
Performance analysis is crucial to the successful development of cloud computing paradigm. And it is especially important for a cloud computing center serving parallelizable application jobs, for determining a proper degree of parallelism could reduce the mean service response time and thus improve the performance of cloud computing obviously. In this paper, taking the cloud based rendering service...
In multi-tier cloud service systems, performance evaluation relies on numerous experiments in order to collect key metrics such as resources usage. The approach may result in highly time-consuming in practice. In this paper, we propose an automated framework for performance tracking, data management and analysis to minimize human intervention in multi-tier cloud service systems. The framework support...
Memcached is a widely used in-memory caching solution in large-scale searching scenarios. The most pivotal performance metric in Memcached is latency, which is affected by various factors including the workload pattern, the service rate, the unbalanced load distribution and the cache miss ratio. To quantitate the impact of each factor on latency, we establish a theoretical model for the Memcached...
Communication networks are large distributed systems designed to send messages from one location to another. Messages are generated by a source and transmitted through a server to their destinations. Servers are connected by the transmission links through which the data flows, and each server has a certain queue capacity. When the number of incoming messages exceeds the capacity of the server or the...
In this paper, we propose a novel secure and privacy-preserving incentive mechanism in vehicular cloud. The proposed incentive mechanism employs a tendering framework to model the interaction between vehicle cloud server and vehicles. With the proposed incentive mechanism, the cloud server can select participated vehicles to collaborate for its announced tasks, and the selected vehicles can earn payments...
Many different types of applications simultaneously execute in current data centers (DCs). To provide low cost and improved performance, each application is typically deployed in distributed DCs. Tasks of users around the world first go through Internet service providers (ISPs) which deliver data between distributed DCs and users. However, capacities and bandwidth cost of different ISPs vary. Besides,...
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