  This paper describes the aDORe repository architecture, designed and
implemented for ingesting, storing, and accessing a vast collection of Digital
Objects at the Research Library of the Los Alamos National Laboratory. The
aDORe architecture is highly modular and standards-based. In the architecture,
the MPEG-21 Digital Item Declaration Language is used as the XML-based format
to represent Digital Objects that can consist of multiple datastreams as Open
Archival Information System Archival Information Packages (OAIS AIPs).Through
an ingestion process, these OAIS AIPs are stored in a multitude of autonomous
repositories. A Repository Index keeps track of the creation and location of
all the autonomous repositories, whereas an Identifier Locator registers in
which autonomous repository a given Digital Object or OAIS AIP resides. A
front-end to the complete environment, the OAI-PMH Federator, is introduced for
requesting OAIS Dissemination Information Packages (OAIS DIPs). These OAIS DIPs
can be the stored OAIS AIPs themselves, or transformations thereof. This
front-end allows OAI-PMH harvesters to recurrently and selectively collect
batches of OAIS DIPs from aDORe, and hence to create multiple, parallel
services using the collected objects. Another front-end, the OpenURL Resolver,
is introduced for requesting OAIS Result Sets. An OAIS Result Set is a
dissemination of an individual Digital Object or of its constituent
datastreams. Both front-ends make use of an MPEG-21 Digital Item Processing
Engine to apply services to OAIS AIPs, Digital Objects, or constituent
datastreams that were specified in a dissemination request.
