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Desktop grids use the free resources in Intranet and Inter-net environments for large-scale computation and storage. While desktop grids offer a high return on investment, one critical issue is the validation of results returned by participating hosts. Several mechanisms for result validation have been previously proposed. However, the characterization of(More)
Web-services and service-oriented architectures are gaining momentum in the area of distributed systems and Internet applications. However, as we increase the abstraction level of the applications we are also increasing the complexity of the underlying middleware. In this paper, we present a dependability benchmarking study to evaluate and compare the(More)
The wide-spread phenomenon of software (running image) aging is known to cause performance degradation, transient failures or even crashes of applications. In this work we describe first a method for monitoring and modeling of performance degradation in SOA applications, particularly application servers. This method works for a large class of the aging(More)
Studies focusing on Unix have shown that the vast majority of workstations and desktop computers remain idle for most of the time. In this paper we quantify the usage of main resources (CPU, main memory, disk space and network bandwidth) of Windows 2000 machines from classroom laboratories. For that purpose, 169 machines of 11 classroom laboratories were(More)
Volunteer Computing harnesses computing resources of machines from around the world to perform distributed independent tasks, following a master/worker model. Despite the recent increase in popularity and power in middleware such as BOINC, there are still several limitations in existing systems. Current research is oriented towards optimizing existing(More)
This paper describes a study of predicting machine availabilities and user presence in a pool of desktop computers. The study is based on historical traces collected from 32 machines, and shows that robust prediction accuracy can be achieved even in this highly volatile environment. The employed methods include a multitude of classification methods known(More)
Performance management and dependability are two of the fundamental issues in business-critical applications. The ability to detect the occurrence of performance failures and anomalies has raised the attention of researchers in the last years. It is in fact a difficult problem, since a visible change in the performance can result from some natural cause(More)