Automaton Meets Algebra: Towards an XML-Centric Stream Query System

数据流处理在当今的许多应用中已经变得至关重要。使用可扩展标记语言（XML）来表示数据的示例流应用包括信息的选择性传播，诸如个性化新闻递送、用于企业对企业（B2B）面向消息的中间件服务器的XML消息代理。这个项目探索了一种新的XML流处理范例，它将基于标记的自动机计算和基于元组的代数计算集成到一个统一的框架中。由此产生的雨滴体系结构支持灵活利用自动机和代数计算范式。除了其他优点之外，这使得能够在这个新的上下文中应用成熟的代数优化技术，例如查询计划重写和成本估计。此外，这种方法可以根据数据统计将操作员推入和推出自动机。Raindrop框架包含了额外的高级功能，例如基于模式的优化，多种执行模式和运行时物理计划重新制定。预计在许多以Internet为中心的实际应用程序中会产生深远的影响，因为这些应用程序可以从基于XML的流监控技术中受益。更广泛的影响包括开发和传播通过该项目的网站（http：//davis.wpi.edu/wipdsrg/raindrop）开发的软件系统，以及按照WPI以项目为基础的教育精神，将PI的研究活动与本科生和研究生教学相结合。

Data-stream processing has become critical in numerous present-day applications. Example stream applications that use Extensible Markup Language (XML) for representing the data include selective dissemination of information such as personalized news delivery, XML message brokers for Business to Business (B2B) message-oriented middleware servers. This project explores a novel paradigm for XML stream processing that integrates token-based automata computation and tuple-based algebraic computation into one uniform framework. The resulting Raindrop architecture supports the flexible exploitation of both automata and algebra computation paradigms. This, among other advantages, enables the application of mature algebraic optimization techniques such as query plan rewriting and cost estimation within this new context. Furthermore, this approach enables pushing operators in and out of the automata, based on data statistics. The Raindrop framework incorporates additional advanced features, such as schema-based optimization, multiple execution modes and run-time physical plan reformulation. A long-reaching impact is expected in many real-world applications that are Internet centric, as these can benefit from the resulting XML-based stream monitoring technology. Broader impacts include the development and dissemination of the software systems developed via the project's Web site (http://davis.wpi.edu/~dsrg/raindrop), and the integration of the PIs' research activities with undergraduate and graduate teaching in line with the project-based spirit of education at WPI.