International audienceContinuously adjusting the horizontal scaling ofapplications hosted by data centers appears as a good candidateto automatic control approaches allocating resources in closedloopgiven their current workload. Despite several attempts,real applications of these techniques in cloud computing infrastructuresface some difficulties. Some of them essentially turnback to the core concepts of automatic control: controllability,inertia of the controlled system, gain and stability. In thispaper, considering our recent work to build a managementframework dedicated to automatic resource allocation in virtualizedapplications, we attempt to identify from experiments thesources of instabilities in the controlled systems. As examples,we analyze two types of policies: threshold-based and reinforcementlearning techniques to dynamically scale resources. Theexperiments show that both approaches are tricky and thattrying to implement a controller without looking at the waythe controlled system reacts to actions, both in time and inamplitude, is doomed to fail. We discuss both lessons learnedfrom the experiments in terms of simple yet key points to buildgood resource management policies, and longer term issueson which we are currently working to manage contracts andreinforcement learning efficiently in cloud controllers
International audienceAutomation of Web service composition is one of the most interesting challenges facing the Service Oriented Computing today. From this challenge, many issues such as control flow, data flow, verification, execution monitoring, or recovery actions (e.g., compensation) follows. In this paper we focus on automated data flow in Web service composition. The semantic Web, as an evolving extension of the current Web, seems a key initiative to overcome the latter issue. However, even if some approaches focus on discovering potential semantic connections between Web services, few or none of these tackle implementations issues related to XML messages management at syntactic level. In this direction we present an approach for performing automated data flow in Web service composition by i) exploiting semantic matchmaking between Web service parameters (i.e., outputs and inputs) to enable their connection and interaction, and ii) adapting XML database solutions, specifically XML Schema mapping, to perform syntactic data transformation and integration of exchanged messages. Our system is implemented and interacting with Web services dedicated on a Telecom scenario. The preliminary evaluation results showed not only high efficiency and effectiveness of the proposed approach but also complementarity of the semantic matchmaking and syntactic mapping to achieving data flow in Web service composition
Territorial male songbirds have the ability to discriminate between the songs of their neighbours and those of strangers and for a few species it has been shown that they maintain this ability from one breeding season to the next. To better understand the acoustic basis of this long-term discrimination ability we studied song stability across two breeding seasons in a migratory songbird with high inter-annual return rates and territory stability, the black redstart, Phoenicurus ochruros. Strophe repertoires of 14 males (≥2 years old) were stable from one breeding season to the next and high strophe sharing occurred for males within the same group of houses or hamlets (81%) in contrast to only limited sharing between different hamlets (15%). However, subtle differences exist between the renditions of the same strophe sung by neighbouring males and these differences equally show an inter-annual stability, providing an acoustic basis for long-term discrimination abilities. Playback tests showed the existence of a strong dear-enemy effect: males reacted less aggressively to the familiar, often shared song of a neighbour than to a stranger unshared song and this pattern was maintained when birds returned from migration one year later. We discuss on one side the possible mechanisms leading to the observed patterns of song sharing and on the other side the significance of stable vocal signatures for neighbour recognition.
This article describes the six-year development process and the undergirding philosophy of the Evangelical Dictionary of World Missions (EDWM). One of a series of reference works published by Baker Book House, the EDWM presents in irenic fashion a broad-based evangelical orientation toward the missionary enterprise. The roughly 1,440 entries (760,000 assigned words) provide comprehensive coverage of the field (including theology, social sciences, history, religions, theory, practice, people, and geography). The writing style enables accessibility for the lay reader, and the additional helps (bibliographies, an outline of the articles, indices, and cross-references) make the EDWM usable for the scholar or student of mission who needs to survey a missiological discipline.
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