Scientific Data Integration: Wrapping Textual Documents with a Database View Mechanism and an XML Engine

Nowadays scientiic data is inevitably digital and stored in a wide variety of formats in heterogeneous systems. Scientists need to access an integrated view of remote or local heterogeneous data sources with advanced data analyzing and visualization tools. Building a digital library for scientiic data requires accessing and manipulating data extracted from at les or documents retrieved from the Web. We present an approach to querying Flat Files as well as Web datasources through an object database view based a database system and a wrapper. Generally a wrapper has two tasks: it rst sends a query to the source to retrieve data and, secondly builds the expected output with respect to the virtual structure. Scientiic data servers and in particular the ones publicly available on the Web, usually provide information retrieval techniques to access data. Our wrappers are composed of a retrieval component based on an intermediate object view mechanism called search views mapping the source capabilities (including full-text retrieval accesses) to attributes, and a XML engine to perform respectively these two tasks. If the retrieval component is speciic to each datasource, this approach shows that the extraction component, the XML engine, can be common. We describe our system and focus on the retrieval component of the Object-Web Wrapper (OWW) for Web sources. The originality of our approach consists of (1) a common wrapper architecture for at les and Web datasources sharing a XML engine for data extraction, (2) a generic view mechanism to access datasources with limited capabilities, and (3) the representation of hyperlinks as abstract attributes in the object view as well as their use in the search view. Our approach has been developed and demonstrated as part of the multidatabase system supporting queries via uniform Object Protocol Model (OPM) interfaces.