The goal of EII systems is to provide uniform access to multiple data sources without having to first load them into a data warehouse. Since the late 1990's, several EII products have appeared in the marketplace and significant experience has been accumulated from fielding such systems. This collection of articles, by individuals who were involved in this industry in various ways, describes some of these experiences and points to the challenges ahead.

For better or for worse, XML has emerged as a de facto standard for data interchange. This consensus is likely to lead to increased demand for technology that allows users to integrate data from a variety of applications, repositories, and partners, which are located across the corporate intranet or on the Internet. Nimble Technology has spent two years developing a product to service this market. Originally conceived after decades of person-years of research on data integration, the product is now being deployed at several Fortune-500 beta-customer sites. The article reports on the key challenges faced in the design of our product and highlights some issues which require more attention from the research community. In particular we address architectural issues arising from designing a product to support XML as its core representation, choices in the design of the underlying algebra, on-the-fly data cleaning and caching and materialization policies.

The consensus that XML has become the de facto standard for data interchange will spur demand for technology that allows users to integrate data from a variety of applications, repositories, and legacy systems which are located across the corporate intranet or at partner companies on the Internet. In the past two years, Nimble Technology has developed a product for this market. Spawned from over a persondecade of data integration research, the product has been deployed at several Fortune-500 beta-customer sites. This abstract reports on the key challenges we faced in the design of our product and highlights some issues we think require more attention from the research community. 1.