Patrick Hochstenbach

The UPS Prototype: An Experimental End-User Service across E-Print Archives

A meeting was held in Santa Fe, New Mexico, October 21--22, 1999, to generate discussion and consensus about interoperability of publicly available scholarly information archives. The invitees represented several well known e-print and report archive initiatives, as well as organizations with interests in digital libraries and the transformation of scholarly communication. The central goal of the meeting was to agree on recommendations that would make the creation of end-user services--such as scientific search engines and linking systems--for data originating from distributed and dissimilar archives easier. The Universal Preprint Service (UPS) Prototype was developed in preparation for this meeting. As a proof-of-concept of a multi-discipline digital library of publicly available scholarly material, the Prototype harvested nearly 200,000 records from several different archives and created an attractive end-user environment. This paper describes the results of the project. This is done in two ways. On the one hand, the experimental end-user service that was created during the project is illustrated. On the other hand, the lessons that the project team drew from the experience of creating the Prototype are presented.

The aDORe federation architecture: digital repositories at scale

The need to federate repositories emerges in two distinctive scenarios. In one scenario, scalability-related problems in the operation of a repository reach a point beyond which continued service requires parallelization and hence federation of the repository infrastructure. In the other scenario, multiple distributed repositories manage collections of interest to certain communities or applications, and federation is an approach to present a unified perspective across these repositories. The high-level, 3-Tier aDORe federation architecture can be used as a guideline to federate repositories in both cases. This paper describes the architecture, consisting of core interfaces for federated repositories in Tier-1, two shared infrastructure components in Tier-2, and a single-point of access to the federation in Tier-3. The paper also illustrates two large-scale deployments of the aDORe federation architecture: the aDORe Archive repository (over 100,000,000 digital objects) at the Los Alamos National Laboratory and the Ghent University Image Repository federation (multiple terabytes of image files).

Using MPEG-21 DIP and NISO OpenURL for the dynamic dissemination of complex digital objects in the Los Alamos National Laboratory digital library

This paper focuses on the use of NISO OpenURL and MPEG-21 Digital Item Processing (DIP) to disseminate complex objects and their contained assets, in a repository architecture designed for the Research Library of the Los Alamos National Laboratory. In the architecture, the MPEG-21 Digital Item Declaration Language (DIDL) is used as the XML-based format to represent complex digital objects. Through an ingestion process, these objects are stored in a multitude of autonomous OAI-PMH repositories. An OAI-PMH compliant Repository Index keeps track of the creation and location of all those repositories, whereas an Identifier Resolver keeps track of the location of individual complex objects and contained assets. An MPEG-21 DIP Engine and an OpenURL Resolver facilitate the delivery of various disseminations of the stored objects. While these aspects of the architecture are described in the context of the LANL library, the paper will also briefly touch on their more general applicability.

Emerging standards for enhanced publications and repository technology: survey on technology

This book consists of two main parts: New Technologies and Communities, and Interoperability. The New Technologies and Communities part contains the following three chapters: one on the Grid, i.e. network, computing community, one on long-term preservation (LTP) strategies and projects, and one on the European CRIS community (Computer Research Information Systems). CRIS-systems are based in research institutions and national administrations, and should evolve into a European-wide e-infrastructure. Of course, there are differences between the repository (publications) and CRIS (research information) communities, but just like Grid computing and LTP, the CRIS community is a related, pan-European community, which deserves a place alongside the other chapters in this publication. The other part of the book, Interoperability, deals with the new standards, formats and evolutions in the repository world and beyond, all related to the dissemination and interoperability of Enhanced Publications. Forthcoming D-NET developments will need to be interoperable with many of these emerging standards because they are being used to disseminate Enhanced Publications. Every chapter of this part describes an emerging standard, a relevant community or platform, and follows a three-tiered approach: theory, case studies and opportunities for DRIVER. The introduction and theoretical framework explains and defines the technology or community in a DRIVER II context, which is followed by case studies and projects that have implemented these standards or technologies, in order to evaluate the relevance and quality for DRIVER. The last part of every chapter always contains the outcomes for DRIVER II, and serves as input for the technical team for the development of D-NET.

File-Based storage of digital objects and constituent datastreams: XMLtapes and internet archive ARC files

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.

Toward sustainable publishing and querying of distributed Linked Data archives

Purpose The purpose of this paper is to detail a low-cost, low-maintenance publishing strategy aimed at unlocking the value of Linked Data collections held by libraries, archives and museums (LAMs). Design/methodology/approach The shortcomings of commonly used Linked Data publishing approaches are identified, and the current lack of substantial collections of Linked Data exposed by LAMs is considered. To improve on the discussed status quo, a novel approach for publishing Linked Data is proposed and demonstrated by means of an archive of DBpedia versions, which is queried in combination with other Linked Data sources. Findings The authors show that the approach makes publishing Linked Data archives easy and affordable, and supports distributed querying without causing untenable load on the Linked Data sources. Research limitations/implications The proposed approach significantly lowers the barrier for publishing, maintaining, and making Linked Data collections queryable. As such, it offers the potential to substantially grow the distributed network of queryable Linked Data sources. Because the approach supports querying without causing unacceptable load on the sources, the queryable interfaces are expected to be more reliable, allowing them to become integral building blocks of robust applications that leverage distributed Linked Data sources. Originality/value The novel publishing strategy significantly lowers the technical and financial barriers that LAMs face when attempting to publish Linked Data collections. The proposed approach yields Linked Data sources that can reliably be queried, paving the way for applications that leverage distributed Linked Data sources through federated querying.