LIQUID: Logic-based Integration and Querying of Unindexed Internet Data

Deep Web由存储在网页之外的数据构成，通常存储在数据库或文件中，并可通过Web表单进行查询来访问。Deep Web数据源除了对其施加本地完整性限制外，还具有由于表单的输入要求而造成的所谓访问限制的特点，而这种限制限制了查询可以“到达”的范围。此外，一般而言，递归查询计划需要提供最大的信息作为对查询的回答。在LIQUID(基于逻辑的无索引互联网数据集成)项目中，我们解决了集成Deep Web源并使其可通过一个全局模式进行查询的问题，该模式代表了所有底层数据。全局模式使用约束来对感兴趣领域的属性进行建模，这些属性不一定由存储在异类源处的数据反映。在这个项目中，我们计划研究表示Deep Web集成系统的形式化方法，并为这些系统设计可扩展的查询处理技术。我们计划研究静态和动态技术，通过使用基于逻辑的约束和访问限制推理技术来降低查询处理成本。我们计划建立一个原型来实现我们的发现。由于形式主义和各种问题的影响，LIQUID将面临雄心勃勃的挑战。

The Deep Web is constituted by data that are stored outside web pages, normallyin databases or files, and are accessible by querying them through web forms.Deep Web data sources, apart from having local integrity constraints enforcedon them, are characterised by so-called access limitations, due to the inputrequirements of the forms, and such limitations restrict the set of that thatcan be ``reached'' by queries. Moreover, in general, recursive query plans areneeded to provide the maximum information as answer to a query. In the projectLIQUID (Logic-based Integration of Unindexed Internet Data), we address theproblem of integrating Deep Web sources and making them queryable through aglobal schema, representing all underlying data. The global schema employsconstraints to model properties of the domain of interest, which are notnecessarily reflected by the data stored at the heterogeneous sources. In thisproject we plan to study formalisms to represent Deep Web integration systems,and to devise scalable query processing techniques for such systems. We planto study static and dynamic techniques to reduce the query processing cost, byemploying logic-based reasoning techniques on constraints and accesslimitations. We plan to build a prototype implementing our findings. LIQUIDwill face ambitious challenges, due to the variety of formalisms and problemsinto play.