Profiling SLAs for cloud system infrastructures and user interactions

Cloud computing has emerged as a cutting-edge technology which is widely used by both private and public institutions, since it eliminates the capital expense of buying, maintaining, and setting up both hardware and software. Clients pay for the services they use, under the so-called Service Level Agreements (SLAs), which are the contracts that establish the terms and costs of the services. In this paper, we propose the CloudCost UML profile, which allows the modeling of cloud architectures and the users’ behavior when they interact with the cloud to request resources. We then investigate how to increase the profits of cloud infrastructures by using price schemes. For this purpose, we distinguish between two types of users in the SLAs: regular and high-priority users. Regular users do not require a continuous service, so they can wait to be attended to. In contrast, high-priority users require a constant and immediate service, so they pay a greater price for their services. In addition, a computer-aided design tool, called MSCC (Modeling SLAs Cost Cloud), has been implemented to support the CloudCost profile, which enables the creation of specific cloud scenarios, as well as their edition and validation. Finally, we present a complete case study to illustrate the applicability of the CloudCost profile, thus making it possible to draw conclusions about how to increase the profits of the cloud infrastructures studied by adjusting the different cloud parameters and the resource configuration.This work was supported by the Spanish Ministry of Science and Innovation (co-financed by European Union FEDER funds) project “FAME (Formal modeling and advanced testing methods. Applications to medicine and computing systems) and MASSIVE (Engineering adaptive software by and for the people in a highly connected world)”, references RTI2018-093608-B-C32 and RTI2018-095255-B-I00. There was also support from the Junta de Comunidades de Castilla-La Mancha project SBPLY/17/180501/000276/ 01 (cofunded with FEDER funds, EU), the Region of Madrid (grant number FORTE-CM, S2018/TCS-4314), and the Madrid Government (Comunidad de Madrid-Spain) under the Multiannual Agreement with the Complutense University as part of the Program to Stimulate Research for Young Doctors in the context of the V PRICIT (Regional Programme of Research and Technological Innovation) under grant PR65/19-2245

Timed Automata Semantics for Visual e-Contracts

C-O Diagrams have been introduced as a means to have a more visual representation of electronic contracts, where it is possible to represent the obligations, permissions and prohibitions of the different signatories, as well as what are the penalties in case of not fulfillment of their obligations and prohibitions. In such diagrams we are also able to represent absolute and relative timing constraints. In this paper we present a formal semantics for C-O Diagrams based on timed automata extended with an ordering of states and edges in order to represent different deontic modalities.Comment: In Proceedings FLACOS 2011, arXiv:1109.239

Una experiencia para fomentar la presencia de la Mujer en Informática a través del 11 de Febrero: Aprendiendo igualdad en la ciencia

La baja presencia de mujeres en carreras de ingeniería en general, y en informática en particular, ha sido reconocida por diferentes estudios internacionales. Esto está ocasionando un sesgo tanto en la industria como en la universidad hacia una visión única de la Informática, perdiendo la riqueza que ofrece siempre la diversidad. Así, nuestro centro, en el contexto de la iniciativa del 11 de Febrero Día Internacional de la Mujer y la Niña en la Ciencia, ha propuesto durante los últimos dos cursos una serie de actividades dirigidas a estudiantes de Secundaria con el fin de hacer visibles a las mujeres en el ámbito de la Ciencia, en general, y en el de la Informática, en particular. Con ello se pretende crear roles femeninos, fuera de estereotipos, y promover prácticas que favorezcan la igualdad de género. Los objetivos últimos son animar a las nuevas generaciones de alumnas a estudiar Ingeniería Informática a fin de romper la brecha de género, y desterrar falsos estereotipos entre los estudiantes sobre las capacidades o competencias de la mujer.The small number of women in engineering studies in general, and in computer science in particular, has been recognized by different international studies. This is causing a bias in both the industry and the university towards a single vision of computing, losing the wealth that diversity always offers. Thus, our Engineering School, in the context of the initiative 11 February, International Day of Women and Girls in Science, has proposed, during the last two academic courses, different activities aimed at high school students to highlight the role of women in the field of Science, in general, and Computer Science, in particular. The main aim is to foster female roles, outside all the stereotypes, and promote practices that favour gender equality. The ultimate goals are to encourage new generations of female students to study Computer Science in order to break the gender gap, and banish false stereotypes among students about the skills or competencies of women

Simcan2Cloud : a discrete-event-based simulator for modelling and simulating cloud computing infrastructures

This work was supported by the Spanish MINECO/FEDER project under grants PID2021-122270OB-I00, TED2021-129381B-C21 and PID2019-108528RB-C22, the Comunidad de Madrid project FORTE-CM under grant S2018/TCS-4314, project S2018/TCS- 4339 (BLOQUES-CM) co-funded by EIE Funds of the European Union and Comunidad de Madrid, Madrid Government (Comunidad de Madrid-Spain) under the Multiannual Agreement with the Complutense University as part of the Program to Stimulate Research for Young Doctors in the context of the V PRICIT (Regional Programme of Research and Technological Innovation) under grant PR65/19-22452, and the University of Castilla-La Mancha (cofunded with FSE funds, EU) under the announcement 2018/12504 published in the DOCM.Cloud computing is an evolving paradigm whose adoption has been increasing over the last few years. This fact has led to the growth of the cloud computing market, together with fierce competition for the leading market share, with an increase in the number of cloud service providers. Novel techniques are continuously being proposed to increase the cloud service provider’s profitability. However, only those techniques that are proven not to hinder the service agreements are considered for production clouds. Analysing the expected behaviour and performance of the cloud infrastructure is challenging, as the repeatability and reproducibility of experiments on these systems are made difficult by the large number of users concurrently accessing the infrastructure. To this, must be added the complications of using different provisioning policies, managing several workloads, and applying different resource configurations. Therefore, in order to alleviate these issues, we present Simcan2Cloud, a discrete-event-based simulator for modelling and simulating cloud computing environments. Simcan2Cloud focuses on modelling and simulating the behaviour of the cloud provider with a high level of detail, where both the cloud infrastructure and the interactions of the users with the cloud are integrated in the simulated scenarios. For this purpose, Simcan2Cloud supports different resource allocation policies, service level agreements (SLAs), and an intuitive and complete API for including new management policies. Finally, a thorough experimental study to measure the suitability and applicability of Simcan2Cloud, using both real-world traces and synthetic workloads, is presented.Publisher PDFPeer reviewe

Using UPPAAL to analyze an MPEG−2 algorithm ⋆

Abstract The performance of a parallel algorithm for an MPEG−2 encoding is analyzed using timed automata models in the UppAal tool. We have constructed both a sequential model of MPEG-2, and a parallel model of MPEG-2 and then, a comparison of the results obtained for both models is made. We show how a model checking tool for timed automata is used to find exact bounds on the performance. Finally, we outline a correctness proof for the parallelization of the algoritm using an untimed bisiumulation relation.