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The widespread adoption of cloud computing has been driven by technological advantages, such as pay-as-you-go plan, scalability and high availability. From cloud service providers point-of-view, managing all these high customer expectations is a growing and critical challenge. This paper examines the relationship among energy infrastructure architectures, checkpoint mechanisms, and availability of software applications in a cloud data center. We consider four power architectures, three checkpoint mechanisms (cold, warm, and hot) with different sizes of files, and two applications (Video on Demand and digital library). For that, we propose a set of stochastic models (based on Petri Net and Reliability Block Diagram) and perform sensitivity and availability analysis. From results, we note that the power architecture has a great impact on application availability while the checkpoint mechanism only impacts with the application has a low mean time to failure value. [ABSTRACT FROM AUTHOR]

Despite the number of users accessing and storing your personal information in cloud services has increased considerably, there still is a certain barrier regarding to cloud adoption. Data security and confidentiality can be considered one of main reasons that affect both sides, clients and cloud providers. Some techinques has been implemented to hamper the data violation and inapropriated access, such as two-factor authentication, that requires two or more factors to liberate the service access to an user. This work presents a performance analisys of two-factor authentication system considering three different virtual environments (KVM, Xen, and VMware Player hypervisors). For the two-factor authentication process, we use the traditional login and password mechanism, and the One Time Password (OTP), as second factor; and for the identity management, we use the OpenID protocol that allows a Single Sign One access. Results show KVM hypervisor has the best performance when compared to two others. [ABSTRACT FROM PUBLISHER]

The Creative Cities movement looks for creative solutions to environmental issues, or inventive ways for people. One of the main objectives of the Creative Cities is to create dynamic and attractive spaces to citizens. For this, information technology can (and should) help in creation of more dynamic environments. Augmented Reality is a technology that overlays virtual objects in the real world, and can be used for this purpose. One way to accomplish Augmented Reality is 3D reconstruction of the environment. This work presents a comparison of libraries for 3D reconstruction, with the objective of developing an application of RA using 3D reconstruction in the context of Creative Cities. In addition, this study also compares and analyzes the performance of virtualization tools (KVM and Virtual Box) when executing this type of application in a cloud infrastructure. [ABSTRACT FROM PUBLISHER]

Summary: Emergency call services are expected to be highly available in order to minimize the loss of urgent calls and, as a consequence, minimize loss of life due to lack of timely medical response. This service availability depends heavily on the cloud data center on which it is hosted. However, availability information alone cannot provide sufficient understanding of how failures impact the service and users' perception. In this paper, we evaluate the impact of failures on an emergency call system, considering service‐level metrics such as the number of affected calls per failure and the time an emergency service takes until it recovers from a failure. We analyze a real data set from an emergency call center for a large Brazilian city. From stochastic models that represent a cloud data center, we evaluate different data center architectures to observe the impact of failures on the emergency call service. Results show that changing data center's architecture in order to improve availability from two to three nines cannot decrease the average number of affected calls per failure. On the other hand, it can decrease the probability to affect a considerable number of calls at the same time. [ABSTRACT FROM AUTHOR]

Abstract Virtualization and cloud computing are being used by Communication Service Providers to deploy and utilize virtual Content Distribution Networks (vCDNs) to reduce costs and increase elasticity thereby avoiding performance, quality, reliability and availability limitations that characterize traditional CDNs. As cache placement is based on both the content type and geographic location of a user request, it has a significant impact on service delivery and network congestion. To study the effectiveness of cache placements and hierarchical network architectures composed of sites, a novel parallel simulation framework is proposed utilizing a discrete-time approach. Unlike other simulation approaches, the proposed simulation framework can update, in parallel, the state of sites and their resource utilization with respect to incoming requests in a significantly faster manner at hyperscale. It allows for simulations with multiple types of content, different virtual machine distributions, probabilistic caching, and forwarding of requests. In addition, power consumption models allow the estimation of energy consumption of the physical resources that host virtual machines. The results of simulations conducted to assess the performance and applicability of the proposed simulation framework are presented. Results are promising for the potential of this simulation framework in the study of vCDNs and optimization of network infrastructure. [ABSTRACT FROM AUTHOR]