Archival storage for digital libraries

We propose an architecture for Digital Library Repositories that assures long-term archival storage of digital objects. The architecture is formed by a federation of independent but collaborating sites, each managing a collection of digital objects. The architecture is based on the following key components: use of signatures as object handles, no deletions of digital objects, functional layering of services, the presence of an awareness service in all layers, and use of disposable auxiliary structures. Long-term persistence of digital objects is achieved by creating replicas at several sites