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This paper presents Rubah, the first <i>dynamic software updating</i> system for Java that: is <i>portable</i>, implemented via libraries and bytecode rewriting on top of a standard JVM; is <i>efficient</i>, imposing essentially no overhead on normal, steady-state execution; is <i>flexible</i>, allowing nearly arbitrary changes to classes between updates;(More)
There have been a few proposals aiming at bridging the gap between institutional grid infrastructures (e.g., Globus-based), popular cycle-sharing applications (e.g., SETIQhome), and massively used decentralized P2P file-sharing applications. Nonetheless, no such infrastructure was ever successful in allowing, in a large-scale, home users to run popular(More)
Data replication is a very relevant technique for improving performance, availability, and scalability. These are requirements of many applications such as multiplayer distributed games, cooperative software tools, etc. However, consistency of the replicated shared state is hard to ensure. Current consistency models and middleware systems lack the required(More)
Volunteer Computing systems (VC) harness computing resources of machines from around the world to perform distributed independent tasks. Existing infrastructures follow a master/worker model, with a centralized architecture. This limits the scalability of the solution due to its dependence on the server. Our goal is to create a fault-tolerant VC platform(More)
Optimistic replication is a fundamental technique for supporting concurrent work practices in mobile environments. However, due to sudden and frequent transitions to weakly connected situations, user experience when accessing replicated data is poor and discourages users from using the replication service. While most research on optimistic replication(More)
Cloud SLAs compensate customers with credits when average availability drops below certain levels. This is too inflexible because consumers lose non-measurable amounts of performance being only compensated later, in next charging cycles. We propose to schedule virtual machines (VMs), driven by range-based non-linear reductions of utility, different for(More)
The use of utility on-demand computing infrastructures, such as Amazon's Elastic Clouds [1], is a viable solution to speed lengthy parallel computing problems to those without access to other cluster or grid infrastructures. With a suitable middleware, bag-of-tasks problems could be easily deployed over a pool of virtual computers created on such(More)
Most distributed garbage collection (DGC) algorithms are not complete as they fail to reclaim distributed cycles of garbage. Those that achieve such a level of completeness are very costly as they require either some kind of synchronization or consensus between processes. Others use mechanisms such as backtracking, global counters, a central server,(More)
Replication of web content, through mirroring of web sites or browsing off-line content, is one of the most used techniques to increase content availability, reduce network bandwidth usage and minimize browsing delays in the world-wide-web.The world-wide-web does not support referential integrity, i.e., broken links do exist. This has been considered, for(More)