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Creating good adaptation policies is critical to building complex autonomic systems since it is such policies that define the system configuration used in any given situation. While online approaches based on control theory and rule-based expert systems are possible solutions, each has its disadvantages. Here, a hybrid approach is described that uses(More)
Virtualization-based server consolidation is an important technique for cost and energy reductions in data center environments and a key enabler of cloud computing. However, to ensure adequate application isolation and performance, consolidation demands runtime resource re-configuration, especially of multi-tier services that have dynamic, rapidly changing(More)
—Server consolidation based on virtualization is a key ingredient for improving power efficiency and resource utilization in cloud computing infrastructures. However, to provide satisfactory performance in such scenarios under changing application workloads, dynamic management of the consolidated resource pool is critical. Unfortunately, this type of(More)
Virtual machine technology enables agile system deployments in which software components can be cheaply moved, replicated, and allocated hardware resources in a controlled fashion. This paper examines how these facilities can be used to provide enhanced solutions to the classic problem of ensuring high availability while maintaining performance. By(More)
Distributed applications typically interact with a number of heterogeneous and autonomous components that evolve independently. Methodical development of such applications can benefit from approaches based on domain-specific languages (DSLs). However, the evolution and customization of heterogeneous components introduces significant challenges to(More)
IT today is driven by the trend of increasing scale and complexity. Utility and Grid computing models, PlanetLab, and traditional data centers, are reaching the scale of thousands of computers. Installed software consists of dozens of interdependent applications and services. As the complexity and scale of these systems continues to grow, it becomes(More)
The characterization of distributed n-tier application performance is an important and challenging problem due to their complex structure and the significant variations in their workload. Theoretical models have difficulties with such wide range of environmental and workload settings. Experimental approaches using manual scripts are error-prone, time(More)
—Parallelization of big-data analytics services over a federation of heterogeneous clouds has been considered to improve performance. However, contrary to common intuition, there is an inherent tradeoff between the level of parallelism and the performance for big-data analytics principally because of a significant delay for big-data to get transferred over(More)
End-to-end automated application design and deployment poses a significant technical challenge. With increasing scale and complexity of IT systems and the manual handling of existing scripts and configuration files for application deployment that makes them increasingly error-prone and brittle, this problem has become more acute. Even though design tools(More)