  This paper introduces the write-once/read-many XMLtape/ARC storage approach
for Digital Objects and their constituent datastreams. The approach combines
two interconnected file-based storage mechanisms that are made accessible in a
protocol-based manner. First, XML-based representations of multiple Digital
Objects are concatenated into a single file named an XMLtape. An XMLtape is a
valid XML file; its format definition is independent of the choice of the
XML-based complex object format by which Digital Objects are represented. The
creation of indexes for both the identifier and the creation datetime of the
XML-based representation of the Digital Objects facilitates OAI-PMH-based
access to Digital Objects stored in an XMLtape. Second, ARC files, as
introduced by the Internet Archive, are used to contain the constituent
datastreams of the Digital Objects in a concatenated manner. An index for the
identifier of the datastream facilitates OpenURL-based access to an ARC file.
The interconnection between XMLtapes and ARC files is provided by conveying the
identifiers of ARC files associated with an XMLtape as administrative
information in the XMLtape, and by including OpenURL references to constituent
datastreams of a Digital Object in the XML-based representation of that Digital
Object.
