1,721,098 research outputs found
WALTy: A User Behavior Tailored Tool for Evaluating Web Application Performance
No full textIn this paper we present WALTy (Web Application Load-based Testing tool), a set of tools that allows the performance analysis of web applications by means of a scalable what-if analysis on the test bed. The proposed approach is based on a workload characterization generated from information extracted from log files. The workload is generated by using of Customer Behavior Model Graphs (CBMG), that are derived by extracting information from the web application log files. In this manner the synthetic workload used to evaluate the web application under test is representative of the real traffic that the web application has to serve. One of the most common critics to this approach is that synthetic workload produced by web stressing tools is far from being realistic. The use of the CBMGs might be useful to overcome this critic
WALTy: A tool for Evaluating Web Application Performance
No full textIn this paper we present WALTy (Web Application Load-based Testing tool), a set of tools that allows the performance analysis of web applications as they are perceived by the end users. The proposed approach is based on a workload characterization created from informations extracted from log files. The workload is generated by using of Customer Behavior Model Graphs (CBMGs) that allow to describe the behaviors of typical users on a web site
Advertisement Delivery and Display in Vehicular Networks: Using V2V Communications for Targeted Ads
Full text linkAdvertisement delivery is expected to play a crucial role in future vehicular networks. In this paper, we address such a problem in vehicular networks, where advertisements (ads) can be broadcasted by roadside units (RSU) as well as vehicles, and then displayed to interested users. We describe the advertisement dissemination process by means of an optimization model that aims at maximizing the number of ads that users display within the target area and validity period of the ad. We then solve the optimization problem, obtaining the optimal scheduling strategy that RSUs and vehicles should adopt for ad broadcasting. Our study highlights the important role that vehicle-to-vehicle communication will have in ads delivery. Also, it shows how coexisting vehicular and cellular networks can effectively complement each other, with vehicular networks being a very efficient means for pervasive ad dissemination
Profit‐aware coalition formation in fog computing providers: A game‐theoretic approach
No full textWe consider fog computing scenarios where data generated by a set of IoT applications need to be processed locally by a set of fog nodes, belonging to distinct Fog Infrastructure Providers (FIPs) sharing the same co‐location facility, with the aim of increasing their profits. This is a challenging goal as it requires reducing costs and meeting QoS targets despite time‐varying workloads. We argue that these FIPs may find it profitable to cooperate by mutually sharing their workload and resources, and we show (by using a game‐theoretical framework) that this is indeed the case when stable coalitions can be formed. Based on these results, in this paper, we present (1) a mathematical model for maximizing the profit obtained for allocating IoT applications to a group of FIPs, and (2) a coalition formation algorithm that allows each FIP to decide with whom to cooperate so as to increment its profits. The efficacy of the devised algorithm is assessed by means of an experimental evaluation taking into account different workload intensities. The results from these experiments show the capability of the proposed algorithm to form coalitions of FIPs that are profitable and stable in all the scenarios we take into consideration
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Stochastic Models for Remote Timing Attacks
No full textIn this paper, we present the first remote timing attack based on
formal stochastic models. Our attack uses queuing models from
the field of performance evaluation to estimate the service times
of different classes of network requests. By using Bayesian statistics, we then identify opportunities for remote timing attacks by
answering the following inverse question: what is the probability
that a given network request belongs to a target class, given an estimate of its service time? Our experimental evaluation on popular
web applications and websites shows that our investigation is not
just a theoretical exercise, because our attack outperforms existing
empirical approaches in terms of standard performance figures. We
believe that the formal foundations put forward in this paper can
be successfully applied to the creation of principled remote timing
attacks which are more effective, because better equipped to deal
with the complexity of the problem they are trying to solve
A Game-Theoretic Approach to Coalition Formation in Fog Provider Federations.
Full text linkIn this paper we deal with the problem of making a set of Fog Infrastructure Providers (FIPs) increase their profits when allocating their resources to process the data generated by IoT applications that need to meet specific QoS targets in face of time-varying workloads. We show that if FIPs cooperate among them, by mutually sharing their workloads and resources, then each one of them can improve its net profit. By using a game-theoretic framework, we study the problem of forming stable coalitions among FIPs. Furthermore, we propose a mathematical optimization model for profit maximization to allocate IoT applications to a set of FIPs, in order to reduce costs and, at the same time, to meet the corresponding QoS targets. Based on this, we propose an algorithm, based on cooperative game theory, that enables each FIP to decide with whom to cooperate in order to increase its profits. The effectiveness of the proposed algorithm is demonstrated through an experimental evaluation considering various workload intensities. The results we obtain from these experiments show the ability of our algorithm to form coalitions of FIPs that are stable and profitable in all the scenarios we consider
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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