Browsing by Author "de Lara, Eyal"
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ItemComponent-based adaptation for mobile computing(2002) de Lara, Eyal; Zwaenepoel, WillyComponent-based adaptation is a novel approach for adapting applications to the limited availability of resources such as bandwidth and power in mobile environments. Component-based adaptation works by calling on the run-time APIs that modern component-based applications export. Because source code modification is not necessary, even proprietary applications such as productivity tools from Microsoft's Office suite can be adapted. Moreover, new adaptive behavior can be added to applications long after they have been deployed. Even if source code is available, development time for implementing adaptation is much reduced. In addition, the ease with which adaptations can be implemented in this framework has enabled me to explore new avenues in adaptation. First, I have developed the first adaptive system to support document editing and collaboration over bandwidth limited links. The key insight gathered from this work is that support for adaptation is orthogonal to concurrency and consistency mechanisms, and therefore can be integrated easily in existing systems. Second, I have developed a hierarchical adaptive transmission scheduler to support coordinated multi-application adaptation. I have demonstrated the effectiveness of component-based adaptation by implementing a system called Puppeteer, which has allowed me to adapt widely deployed applications, such as productivity tools from Microsoft's Office suite and Sun Microsystems' OpenOffice suite. Although the APIs of these applications impose some limitations, I have been able to implement a wide range of adaptation policies for reading, editing, and collaboration, with modest implementation effort and good performance results. ItemPuppeteer: Component-based Adaptation for Mobile Computing(2000-03-20) de Lara, Eyal; Wallach, Dan S.; Zwaenepoel, Willy; Center for Multimedia Communications (http://cmc.rice.edu/)Puppeteer is a system for adapting component-based applications in mobile environments. Puppeteer takes advantage of the exported interfaces of these applications to perform adaptation without modifying the applications. The system is structured in a modular fashion, allowing easy addition of new applications and adaptation policies. Our initial prototype focuses on adaptation to limited bandwidth. It runs on Windows NT and includes support for a variety of adaptation policies for Microsoft PowerPoint and Internet Explorer 5. We demonstrate that Pupeteer can support complex policies without any modification to the application and with little overhead. To the best of our knowledge, previous implementations of adaptations of this nature have relied on modifying the application. ItemThe effect of contention on the scalability of page-based software shared memory systems(1999) de Lara, Eyal; Zwaenepoel, WillyWe demonstrate the profound effects of contention on the performance of page-based software distributed shared memory systems, as such systems are scaled to a larger number of nodes. Programs whose performance scales will experience only minor increases in memory latency, do not suffer from contention, and show a balanced communication load. In contrast, programs that scaled poorly suffered from large memory latency increases due to contention and communication imbalance. We use two existing protocols, Princeton's home-based protocol and the TreadMarks protocol, and a third novel protocol, Adaptive Striping. For most of our programs, all three protocols were equally affected by latency increases and achieved similar performance. Where they differ significantly, the communication load imbalance, which is caused by the read accesses to pages that have multiple readers following one or more writers, is the largest factor accounting for the difference.