Dataspaces: Co-existence with Heterogeneity

Most information management scenarios today rarely have a situation in which all the data that needs to be man-aged can t nicely into a single management system, such as a relational database or a knowledge base. Instead, we need to manage a set of loosely connected data sources, and typically face the following recurring challenges: Users want be able to search the entire collection without having knowledge of individual sources. In some cases, they merely want to know where the information exists as a starting point to further exploration. An organization may want to enforce certain rules, in-tegrity constraints, or conventions (e.g., on naming enti-ties) across the entire collection, or track ow and lineage between systems. Furthermore, the organization needs to create a coherent external view of the data