Ramsés Morales

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This paper proposes a new execution model for confidentiality and privacy in cloud computing, called the HybrEx (Hybrid Execution) model. The HybrEx model provides a seamless way for an organization to utilize their own infrastructure for sensitive, private data and computation, while integrating public clouds for non-sensitive, public data and computation.(More)
—This paper proposes to build overlays that help in the monitoring of long-term availability histories of hosts, with a focus on large-scale distributed settings where hosts may be selfish or colluding (but not malicious). Concretely, we focus on the important problems of selection and discovery of such an availability monitoring overlay. We motivate six(More)
— While peer-to-peer overlays allow distributed applications to scale and tolerate failures, most structured and unstructured overlays in literature today are inflexible from the application viewpoint. The application thus has no first-class control on the overlay structure. This paper proposes the concept of an application-malleable overlay, and the design(More)
Peer-to-peer overlays allow distributed applications to work in a wide-area, scalable, and fault-tolerant manner. However, most structured and unstructured overlays present in literature today are inflexible from the application viewpoint. In other words, the application has no control over the structure of the overlay itself. This paper proposes the(More)
Monitoring and management operations that query nodes based on their availability can be extremely useful in a variety of large-scale distributed systems containing hundreds to thousands of hosts, e.g., p2p systems, Grids, and PlanetLab. This paper presents decentralized and scalable solutions to a subset of such availability-based management tasks.(More)
Distributed systems are typically designed for scale and performance first, which makes it difficult to add security later without affecting the original properties. This paper proposes the design of the Folklore persistent distributed storage system, which adopts an alternative design methodology. Folklore's design relies on a single core protocol for(More)
Aggregation of system-wide information in large-scale distributed systems, such as p2p systems and Grids, can be unfairly influenced by nodes that are selfish, colluding with each other, or are offline most of the time. We present AVCOL, which uses probabilistic and gossip style techniques to provide availability-aware aggregation. Concretely, AVCOL is the(More)
Distributed computations, dealing with large amounts of data, are scheduled in Grid clusters today using either a task-centric mechanism, or a worker-centric mechanism. Because of the large data sets, the execution time is bounded by the cost of data transfer. In this paper, we introduce new worker-centric scheduling strategies that are novel in that they(More)
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