aDORe Projects

The aDORe Federation is a federated repository framework and reference implementation which aims to address many of the scalability issues experienced by large scale digital object repositories. The goal of the aDORe federation architecture is to facilitate a uniform manner for client applications to discover and access content objects available in a group of distributed repositories. This is achieved by means of a 3-Tier architecture, which identifies the core service interfaces necessary to develop a stackable repository framework. The aDORe Archive is provided as a Tier-1 reference implementation.

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The aDORe Archive is a write-once/read-many 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, valid XML file named an XMLtape. 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. 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. The interconnection between an XMLtape and its associated ARC file(s) is provided by conveying the identifiers of these ARC files 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 stored in the XMLtape.

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DIDLTools is a Java toolkit for the construction, validation, serialization and de-serialization for MPEG-21 DIDL data model. DIDL, the MPEG-21 Digital Item Declaration Language, provides a hierarchical structure which allows each digital item to be modeled in the most appropriate fashion. The DID API allows for the construction of customized DID models, as well as provides flexible and extensible serialization methods.

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The aDORe OAI Resource Harvester is a framework that facilitates collecting resources described by metadata records exposed by OAI-PMH repositories. Metadata records are harvested using the OAI-PMH, and written to write-once/read-many XML wrappers for a collection of XML documents, named XMLTapes. Plug-in based dereferencing implementations that are typically repository-dependent then collect the digital resources described by the harvested records. Collected datastreams are then written to Internet Archive ARC files. The results of these actions are written to control files indicating processing status and the relationship between harvested records and collected digital resources.

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