Schema Mappings and Automated Services for Data Integration and Exchange

这个项目主要是在数据库理论领域，在数据交换和数据集成的上下文中处理模式映射。数据交换是将一个或多个源模式下结构化的数据插入到不同结构(可能具有完整性约束)的目标模式中，同时尽可能准确地反映源数据的问题。数据集成是回答在目标模式上提出的查询的问题，该目标模式集成了一个或多个源模式上的多个数据源提供的信息。为了取得重大进展，我们将研究这两个问题变得容易处理和可行的模式映射类。我们不会局限于研究一个源模式和一个目标模式之间的单一模式映射，我们还将考虑更一般的设置，其中几个模式通过不同的模式映射及其组合连接在一起。我们将从框架开始，在该框架中，对模式映射和数据库的完整性约束由任意嵌入的依赖项给出。这种设置过于笼统，需要加以限制以获得可操纵性。因此，在全面复杂性分析的背景下，我们将确定关键参数，分析限制(例如，对某些参数施加限制)，并调查易于处理的设置。基于这些结果，我们将设计新的数据交换和集成算法。我们将研究如何通过Web服务最好地执行数据交换和集成，并开发一个模型。最后，我们将在本文中实现和测试我们的新算法。该项目分为四个主要工作包。WP1主要通过Chase过程的新变体来研究数据交换问题解的有效计算。WP2专注于简洁解的有效计算，即所谓的核，以及对模式映射的代数性质的研究。WP3由一项全面的复杂性研究组成，该研究基于各种参数跟踪数据交换问题的可处理性边界。在WP3中。我们还将开发启发式算法来处理计算困难的问题。在WP4中，我们将阐述一个使用Web服务技术进行数据集成和交换的新模型，并在该模型中实现和测试我们的新算法和方法，并测试总体方法的可行性。预计两名学生将密切合作，其中一名学生将做更多以理论为导向的工作，而另一名学生将花费更多时间开发用于数据集成和交换的Web服务模型。我们计划在顶级数据库期刊和领先的国际会议上发布结果。Web服务将向公众开放。

This project, which is predominantly in the area of database theory, deals with schema mappings in the context of data exchange and data integration. Data Exchange is the problem of inserting data structured under one or more source schemas into a target schema of different structure (possibly with integrity constraints) while reflecting the source data as accurate as possible. Data Integration is the problem of answering queries formulated over a target schema that integrates the information provided by several data sources over one or more source schemas. In order to achieve significant progress, we will study classes of schema mappings for which these two problems become tractable and practicable. Rather than restricting ourselves to the study of single schema mappings between one source and one target schema, we will also consider more general settings, where several schemas are connected by various schema mappings and their compositions. We will start from the framework where the integrity constraints on schema mappings and databases are given by arbitrary embedded dependencies. This setting is far too general and needs to be restricted in order to obtain tractability. In the context of a comprehensive complexity analysis, we will therefore identify critical parameters, analyze restrictions (e.g. imposing bounds to some parameters) and investigate tractable settings. Based on these results, we will then design new algorithms for data exchange and integration. We will study how data exchange and integration can be best performed via Web services and develop a model. Finally, we will implement and test our new algorithm sin this context.The project is organised into four main work packages. WP1 studies the efficient computations of solutions to data exchange problems, mainly through new variants of the Chase procedure. WP2 focuses on the efficient computation of succinct solutions, so called cores and of the study of algebraic properties of schema mappings. WP3 consists of a comprehensive complexity study tracing the tractability frontier for data exchange problems based on various parameters. In WP3. we will also develop heuristics for dealing with computationally hard problems. In WP4, we will elaborate a new model for using Web service technology for data integration and exchange, and we will implement and test our new algorithms and methods in that model, and test the feasibility of the overall approach.The scientific project staff will consist of the applicant (part time), one post-doc, and two doctoral students. While both students are expected to intensively co-operate with each other, one will do more theory-oriented work, while the other student will spend more time on developing the Web-service model for data integration and exchange.We plan to publish the results in top database journals and at leading international conferences. The Web services will be made accessible to the public.