Dynamic recomposition of documents from distributed data sources

Dynamic recomposition of documents refers to the process of on-the-fly creation of documents. A document can be generated from several documents that are stored at distributed data sites. The source can be queried and results obtained in the form of XML. These XML documents can be combined after a series of transformation operations to obtain the target document. The resultant document can be stored statically or in the form of a command, which can be invoked later to recompose this document dynamically. Also, in case a change is made to a document, then only the change can be stored, instead of storing the modified document in its entirety. The purpose of this research was to provide a way to recompose dynamic documents. A solution is proposed at the level of algebra for update and recomposition of documents stored at distributed data sources. The issue of representation of a document by a command, i.e., a composition operator and/or an editing command along with one or more path expressions has also been researched. The construction of a dynamic document has three phases to it. The first one is the information retrieval. Phase two deals with building of real document: this includes the filtering of retrieved data by selecting relevant subset of a document and then applying update operations, and finally the ordering and assembling of the document. The final phase consists of displaying or storing or exchanging it over the web through a convenient means

An algebraic approach for incremental maintenance of materialized XQuery views

Modern data sources, including structural and semi-structural sources, often export XML views over base data, and at times may materialize their views by storing the XML query result to provide faster data access. It is typically more efficient to maintain a view by incrementally propagating the base changes to the view than by re-computing it from scratch. Techniques for the incremental maintenance of relational views have been extensively studied in the literature. However, the maintenance of views created using XQuery is as of now unexplored. In this paper we propose an algebraic approach for incremental XQuery view maintenance. In our approach, an update to the XML source is transformed into a set of well defined update primitives which are propagated through the XML algebra tree. This algebraic update propagation process generates incremental update primitives to be applied to the result view. We briefly discuss our XQuery view maintenance system implementation. Our experiments confirm that incremental view maintenance is indeed faster than re-computation. Categories and Subject Descriptors H.2.3 [Database Management]: Languages—Query languages