1,721,004 research outputs found
Big-data applications as self-Adaptive systems of systems
No full textVirtualization technologies have enabled a new way of thinking of computing resources and cloud computing frameworks offer many pay-per-use solutions for renting these resources. Conventional physical servers had to be acquired, provisioned, and configured beforehand; virtual resources can be allocated on demand, and changes can be managed quickly. Deploying systems on virtualized resources allows one to allocate resources given the actual workload and KPIs of interest, but it requires that resource management be part of the system itself. Traditional application components must be augmented with probes and actuators to sense the application behavior and provision resources accordingly. Big data applications are a prominent example of these modern systems, and the paper discusses dynaSpark, that is, the work done by the authors to extend Spark standalone-A well-known framework widely used for parallel processing and big data applications-And augment it with resource management capabilities. It also introduces the key problems the integration and the particular batch applications bring in, and identifies additional aspects that are still to be taken into account and that would lead to a better solution
Deriving Models of Software Fault-proneness
No full textThe effectiveness of the software testing process is a key issue for meeting the increasing demand of quality without augmenting the overall costs of software development. The estimation of software fault-proneness is important for assessing costs and quality and thus better planning and tuning the testing process. Unfortunately, no general techniques are available for estimating software fault-proneness and the distribution of faults to identify the correct level of test for the required quality. Although software complexity and testing thoroughness are intuitively related to the costs of quality assurance and the quality of the final product, single software metrics and coverage criteria provide limited help in planning the testing process and assuring the required quality. By using logistic regression, this paper shows how models can be built that relate software measures and software fault-proneness for classes of homogeneous software products. It also proposes the use of cross-validation for selecting valid models even for small data sets. The early results show that it is possible to build statistical models based on historical data for estimating fault-proneness of software modules before testing, and thus better planning and monitoring the testing activities
Assertions to Better Specify the Amazon Bug
No full textModern Web applications are mainly distributed systems that exploit the Internet as communication means and the Web as neutral interface to access services and data. The addition of services to Web applications poses problems that are usually tackled at the technology level, but that should be addressed during design to deliver quality Web applications. A typical example of these problems is the Amazon bug, an annoying problem that the user could encounter if after adding products to his shopping cart, he rolls back to a page with a previous version of the cart and tries to buy it. This would make the user buy the last version of the cart's contents, which in some subtle cases could be different from what expected. In this paper, we do not want to discuss all design aspects, but only how provided services/operations should jointly be designed with the rest of the system. We propose a new reference model for Web applications: Operations require a more complex model where they are not simply appended to information and navigation elements, but they can cooperate with them. Besides the reference model, the paper proposes the use of assertions to constraint the behavior of designed operations. Assertions do not only predicate on how data should be modified, but must also take into account how presentation and navigation could be affected by the execution of the operation
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
Guess the State: Exploiting Determinism to Improve GUI Exploration Efficiency
No full textMany automatic Web testing techniques generate test cases by analyzing the GUI of the Web applications under test, aiming to exercise sequences of actions that are similar to the ones that testers could manually execute. However, the efficiency of the test generation process is severely limited by the cost of analyzing the content of the GUI screens after executing each action. In this paper, we introduce an inference component, Sibilla, which accumulates knowledge about the behavior of the GUI after each action. Sibilla enables the test generators to reuse the results computed for GUI screens that recur multiple times during the test generation process, thus improving the efficiency of Web testing techniques. We experimented Sibilla with Web testing techniques based on three different GUI exploration strategies (Random, Depth-first, and Q-learning) and nine target systems, observing reductions from 22% to 96% of the test generation time
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
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