Browsing by Author "Lara, Eyal de"
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Item A Characterization of Compound Documents on the Web(1999-11-29) Lara, Eyal de; Wallach, Dan S.; Zwaenepoel, WillyRecent developments in office productivity suites make it easier for users to publish rich {\em compound documents\/} on the Web. Compound documents appear as a single unit of information but may contain data generated by different applications, such as text, images, and spreadsheets. Given the popularity enjoyed by these office suites and the pervasiveness of the Web as a publication medium, we expect that in the near future these compound documents will become an increasing proportion of the Web's content. As a result, the content handled by servers, proxies, and browsers may change considerably from what is currently observed. Furthermore, these compound documents are currently treated as opaque byte streams, but future Web infrastructure may wish to understand their internal structure to provide higher-quality service. In order to guide the design of this future Web infrastructure, we characterize compound documents currently found on the Web. Previous studies of Web content either ignored these document types altogether or did not consider their internal structure. We study compound documents originated by the three most popular applications from the Microsoft Office suite: Word, Excel, and PowerPoint. Our study encompasses over 12,500 documents retrieved from 935different Web sites. Our main conclusions are: Compound documents are in general much larger than current HTML documents. For large documents, embedded objects and images make up a large part of the documents' size. For small documents, XML format produces much larger documents than OLE. For large documents, there is little difference. Compression considerably reduces the size of documents in both formats.Item Component-Based Adaptation for Mobile Computing(2003-01-25) Lara, Eyal deComponent-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.Item Puppeteer: Component-based Adaptation for Mobile Computing(2000-07-06) Lara, Eyal de; Wallach, Dan S.; Zwaenepoel, WillyPuppeteer is a system for adapting component-based applications in mobile environments. Puppeteer takes advantage of the component-based nature of the applications to perform adaptation without modifying the applications. We illustrate the power of Puppeteer by demonstrating adaptations that would otherwise require significant modifications to the application. Our initial prototype supports Microsoft PowerPoint and Internet Explorer~5 without requiring any changes to the applications. It supports delayed data and image transmission as well as progressive image refinement. We measure our system's effectiveness with a large number of PowerPoint documents and Web pages. We measure user-perceived latencies for a variety of adaptation policies and over a variety of different network bandwidths. Our results show that Puppeteer can achieve average reductions in user latency of up to 84.22% for PowerPoint documents loaded over a 384~Kb/sec link and 76.42% for HTML documents loaded over 56~Kb/sec link.