SUPPORTING DATABASE APPLICATIONS AS A SERVICE

Master'sMASTER OF SCIENC

Arquitecturas para sistemas de informação baseados em cloud computing

Mestrado em Engenharia dos Computadores e TelemáticaEste trabalho faz um apanhado do panorama actual no que diz respeito a Cloud computing. Começa por analisar a definição proposta pelo NIST e cate-gorizar vários serviços comerciais de acordo com as categorias propostas nes-sa definição. De seguida, são analisadas as implementações grátis disponíveis em licenças Open Source e chega-se à conclusão que para Clouds do tipo IaaS já existem várias implementações, algumas com boa qualidade, mas que na área de PaaS ainda existe muito trabalho a ser feito antes de se chegar a uma imple-mentação com funcionalidade comparável à dos serviços comerciais existen-tes. Após uma breve análise sobre a integração de SOA com as facilidades do Cloud computing, chegou-se à conclusão que PaaS se apresenta como o modelo de serviço mais adequando para desenvolver aplicações SOA. Visto que não existe ainda nenhum PaaS livre, e que os existentes apresentam problemas sérios de vendor lock in, é especificada uma framework completa, portátil e aberta que permitirá implementar um serviço do tipo PaaS em infra-estrutura privada ou sobre algum dos IaaS existentes. O PaaS especificado baseia-se, sempre que possível, em tecnologias existen-tes, concluindo-se que apenas a tecnologia de armazenamento de dados estruturados está aquém do necessário para a implementação. Deixa-se para o futuro a implementação dos vários módulos que permitirão a integração dos vários componentes da PaaS, no entanto sempre que possível, são sugeridas tecnologias a utilizar de forma a manter a implementação aberta e portátil.This work sums up the current situation of Cloud computing. It starts by per-forming an analysis of the NIST definition draft, and categorizing some com-mercial services into the categories proposed by the referred definition. Next, the free implementations distributed under an Open Source license are analyzed, and the conclusion is that there are some high quality IaaS cloud implementations, but the PaaS area still needs a lot of work before the functio-nality of a free implementation is comparable to that of the commercial services available. After a brief analysis of the integration of SOA and Cloud computing, the con-clusion is that PaaS presents the most adequate service model for the devel-opment of SOA applications. Given that, up to the moment, there is no free PaaS, and that the existing ones present serious vendor lock in problems, a complete, portable, and open framework that allows the deployment of a PaaS type service on private or on IaaS infrastructure is specified. The specified PaaS is based on current technology whenever possible, with exception of the storage of structured data that is not up to the requirements yet. The implementation of the modules required to integrate the various PaaS components is left as future work. Yet, whenever possible, suggestions are made about usable technologies that will allow the PaaS to remain portable and open

HIL: designing an exokernel for the data center

We propose a new Exokernel-like layer to allow mutually untrusting physically deployed services to efficiently share the resources of a data center. We believe that such a layer offers not only efficiency gains, but may also enable new economic models, new applications, and new security-sensitive uses. A prototype (currently in active use) demonstrates that the proposed layer is viable, and can support a variety of existing provisioning tools and use cases.Partial support for this work was provided by the MassTech Collaborative Research Matching Grant Program, National Science Foundation awards 1347525 and 1149232 as well as the several commercial partners of the Massachusetts Open Cloud who may be found at http://www.massopencloud.or

Priority-Driven Differentiated Performance for NoSQL Database-As-a-Service

Designing data stores for native Cloud Computing services brings a number of challenges, especially if the Cloud Provider wants to offer database services capable of controlling the response time for specific customers. These requests may come from heterogeneous data-driven applications with conflicting responsiveness requirements. For instance, a batch processing workload does not require the same level of responsiveness as a time-sensitive one. Their coexistence may interfere with the responsiveness of the time-sensitive workload, such as online video gaming, virtual reality, and cloud-based machine learning. This paper presents a modification to the popular MongoDB NoSQL database to enable differentiated per-user/request performance on a priority basis by leveraging CPU scheduling and synchronization mechanisms available within the Operating System. This is achieved with minimally invasive changes to the source code and without affecting the performance and behavior of the database when the new feature is not in use. The proposed extension has been integrated with the access-control model of MongoDB for secure and controlled access to the new capability. Extensive experimentation with realistic workloads demonstrates how the proposed solution is able to reduce the response times for high-priority users/requests, with respect to lower-priority ones, in scenarios with mixed-priority clients accessing the data store