We present MinervaDL, a digital library architecture that supports approximate information retrieval and filtering functionality under a single unifying framework. The architecture of MinervaDL is based on the peer-to-peer search engine Minerva, and is able to handle huge amounts of data provided by digital libraries in a distributed and self-organizing way. The two-tier architecture and the use of the distributed hash table as the routing substrate provides an infrastructure for creating large networks of digital libraries with minimal administration costs. We discuss the main components of this architecture, present the protocols that regulate node interactions, and experimentally evaluate our approach.