1,132 research outputs found

    Book Review

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    Par EntreMundos: A Pedagogy of the AméricasEd. Jennifer Ayala, Julio Cammarota, Margarita I. Berta- Ávila, Melissa Rivera, Louie F. Rodríguez, and María Elena Torre. Peter Lang PublishingPublished: 2018Pages: 259Price: $131.20 (Hardback

    Automating SLA-Driven API Development with SLA4OAI

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    The OpenAPI Specification (OAS) is the de facto standard to describe RESTful APIs from a functional perspective. OAS has been a success due to its simple model and the wide ecosystem of tools supporting the SLA-Driven API development lifecycle. Unfortunately, the current OAS scope ignores crucial information for an API such as its Service Level Agreement (SLA). Therefore, in terms of description and management of non-functional information, the disadvantages of not having a standard include the vendor lock-in and prevent the ecosystem to grow and handle extra functional aspects. In this paper, we present SLA4OAI, pioneering in extending OAS not only allowing the specification of SLAs, but also supporting some stages of the SLA-Driven API lifecycle with an open-source ecosystem. Finally, we validate our proposal having modeled 5488 limitations in 148 plans of 35 real-world APIs and show an initial interest from the industry with 600 and 1900 downloads and installs of the SLA Instrumentation Library and the SLA Engine.Ministerio de Economía y Competitividad TIN2015-70560-RMinisterio de Ciencia, Innovación y Universidades RTI2018-101204-B-C21Ministerio de Educación, Cultura y Deporte FPU15/0298

    Governing the service-chain: Challenges ahead

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    As Information Systems are evolving into an ecosystem of services, organizations face the persistent challenge of IT governance. In such a context, Cloud Computing shift has supported a growing service chain that has transformed the business model from industry. In this position paper we outline the dimensions of this service chain reality and the role of Service Level Agreement as a foundation to support its governance challenge

    Fostering SLA-Driven API Specifications

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    Software architecture tendencies are shifting to a microservice paradigm. In this context, RESTful APIs are being established the standard of integration. API designer often identifies two key issues to be competitive in such growing market. On the one hand, the generation of accurate documentation of the behavior and capabilities of the API to promote its usage; on the other hand, the design of a pricing plan that fits into the potential API user’s needs. Besides the increasing number of API modeling alternatives is emerging, there is a lack of proposals on the definition of flexible pricing plans usually contained in the Service Level Agreements (SLAs). In this paper we propose two different modeling techniques for the description of SLA in a RESTful API context: iAgree and SLA4OAI.Ministerio de Economía y Competitividad TIN2015-70560-RJunta de Andalucía P12-TIC-1867Ministerio de Economía y Competitividad TIN2014-53986-RED

    Study and analysis of state-of-the-art FCS-MPC strategies for thermal regulation of power converters

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    La degradación en los convertidores de potencia basados en silicio, enmarcados en sistemas de tracción eléctrica y fuentes de energías renovables, es un tema de estudio de especial interés para aquellas aplicaciones donde los fallos amenazan la seguridad de personas o donde el mantenimiento es particularmente costoso. Motivado por la influencia de los fallos en IGBTs sobre los fallos habituales en los convertidores de potencia comunes, este trabajo utiliza la herramienta software PLECS como marco de trabajo para la simulación de algoritmos de control predictivo basado en modelo con conjunto finito de acciones de control (FCS-MPC) que pretenden -simultáneamente a conseguir el seguimiento eléctrico- extender directa o indirectamente la vida útil de los IGBTs. El trabajo se enfoca principalmente a la simulación en ordenador de los algoritmos controlando un inversor de dos niveles conectado a una carga RL. Además, pretende también introducir la implementación de éstos sobre un microcontrolador para su estudio controlando el inversor simulado en la plataforma PLECS RT Box 1, con el fin último de poder desarrollar validaciones de los controladores basadas en técnicas Hardware-In-the-Loop.Degradation of silicon-based power electronics converters in traction and renewable energy systems is a topic of interest particularly where module failure supposes a safety threat or where maintenance becomes especially expensive. Motivated by the influence of IGBT aging in usual power converters, this work uses the software tool PLECS as framework to simulate Finite Control Set Model Predictive Control (FCSMPC) algorithms that, simultaneously to achieving a certain current tracking, aim to directly or indirectly extend IGBTs’ lifetime. Whilst the work focuses on offline simulation of the algorithms on PLECS, it also targets to pave the way to implement algorithms in a micro-controller and to study how they control a two-level inverter connected to a RL load simulated on a PLECS RT Box 1 platform. The ultimate goal is to develop validations based on Hardware-In-the-Loop techniques of the control algorithms.Universidad de Sevilla. Máster Universitario en Ingeniería Electrónica, Robótica y Automátic

    Releasing constraints to growth or pushing on a string ? the impact of credit, training, business associations, and taxes on the performance of Mexican micro-firms

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    The authors employ propensity score matching and a traditional control function approach to examine the impact of participation in various societal institutions on microfirm performance in Mexico. They find that firms that participate in credit markets, receive training,pay taxes, and belong to business associations exhibit significantly higher profits, even after controlling for the various factors that drive participation in those institutions. They also find that firms that borrow from formal or informal sources and those that pay taxes are significantly more likely to stay in business, but firms that received credit exhibit lower rates of income growth. Overall, the results suggest that even if the best performing micro-firms are more likely to be selected into participating in societal institutions, causality also runs in the opposite direction. In particular, increases in strictly or broadly defined formality have the potential for increasing profits and survival rates, and appear to bring micro-firms closer to their optimal sizes.Economic Theory&Research,Science Education,Scientific Research&Science Parks,Investment and Investment Climate,Educational Sciences

    Does Formality Improve Micro-Firm Performance? Quasi-Experimental Evidence from the Brazilian SIMPLES Program

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    This paper employs regression discontinuity methods to identify the effect of formality on Brazilian micro-firm performance. The SIMPLES program introduced in November 1996 consolidated multiple taxes and social security contributions into a single payment and reduced taxes for eligible small firms. This provides a quasi-natural experiment that allows us to eliminate many of the endogeneity issues surrounding the impact of formality, measured across several dimensions, on firm performance. We find that SIMPLES had a significant effect on the proportion of firms that have a license to operate, are registered as a legal entity, pay taxes and make social security contributions. Moreover, newly created firms that opt for operating formally achieve higher levels of revenue and profits, employ more workers and are more capital intensive (only for those firms that have employees). The channel through which this occurs is not access to credit or contracts with larger firms. Rather, it appears that the lower cost of contracting labor leads to adopting production techniques that involve greater permanence and a larger paid labor force.micro-firms, self-employment, informality

    ELeCTRA: Induced Usage Limitations Calculation in RESTful APIs

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    As software architecture design is evolving to microservice paradigms, RESTful APIs become the building blocks of applications. In such a scenario, a growing market of APIs is proliferating and developers face the challenges to take advantage of this reality. For example, third-party APIs typically define different usage limitations depending on the purchased Service Level Agreement (SLA) and, consequently, performing a manual analysis of external APIs and their impact in a microservice architecture is a complex and tedious task. In this demonstration paper, we present ELeCTRA, a tool to automate the analysis of induced usage limitations in an API, derived from its usage of external APIs. This tool takes the structural, conversational and SLA specifications of the API, generates a visual dependency graph and translates the problem into a constraint satisfaction optimization problem (CSOP) to obtain the optimal usage limitations.Ministerio de Economía y Competitividad TIN2015-70560-RJunta de Andalucía P12–TIC–1867Ministerio de Economía y Competitividad TIN2014-53986-REDTMinisterio de Educación, Cultura y Deporte FPU15/0298

    Temporal-Awareness in SLAS. Why Should We Be Concerned?

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    Traditionally, Service Level Agreements have been decomposed in two sets of properties: functionals (what) and non-functionals (how). However, in our opinion, there has been a third key element that has had a minor attention from academy: temporal awareness (when). We believe temporality is a main concern that should be addressed in realistic scenarios. in doing so, this position paper discuss our experience in extending the specification WS-Agreement with a temporal Domain Specific Language; importantly, main aim of the paper is to provoke a debate about the importance of temporality in SLAs
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