NCore: Architecture and Implementation of a Flexible, Collaborative   Digital Library
  NCore is an open source architecture and software platform for creating flexible, collaborative digital libraries. NCore was developed by the National Science Digital Library (NSDL) project, and it serves as the central technical infrastructure for NSDL. NCore consists of a central Fedora-based digital repository, a specific data model, an API, and a set of backend services and frontend tools that create a new model for collaborative, contributory digital libraries. This paper describes NCore, presents and analyzes its architecture, tools and services; and reports on the experience of NSDL in building and operating a major digital library on it over the past year and the experience of the Digital Library for Earth Systems Education in porting their existing digital library and tools to the NCore platform. 
Dean B. Krafft, Aaron Birkland, Ellen J. Cramer