A System Administrator has to maintain a federation of repositories: one for streaming media, another repository for textual objects, and one for large-scale numerical data sets. Each repository runs on dedicated hardware systems with differing architectures. All repositories are utilized by the same group of researchers. Data objects of researchers are often stored in more than one of those repositories. The System Administrator needs to ensure consistent users, roles, and access rights across all repositories. Thus, she requires a single point of administration for user and access management for the distributed repository infrastructure. Any change at this single point of administration should (immediately/near real-time) be reflected in all repositories under her control.