EU-NSF Working Group on Interoperability between Digital Libraries
by Daniel L. Kiskis and Uwe Röhm
The first joint meeting of the working group on Interoperability
between Digital Library Systems took place 10-11 February 1998 at ETH Zurich,
Switzerland. The purpose of this meeting was to exchange ideas and opinions
between the working group members and to generate a report on future research
directions on interoperability between digital libraries.
The Interoperability working group assembles researchers from digital
library systems and database and information systems. The US part, lead
by William P. Birmingham (University of Michigan), is formed of Barry Leiner
(MCC), Andreas Paepcke (Stanford University), Daniel Kiskis (University
of Michigan), and Steve Ketchpel (Stanford University). The European side
is represented by Vassilis Christophides (FORTH), Sophie Cluet (INRIA),
Panos Constantoupoulos (FORTH), Sverker Janson (SICS), Olle Olsson (SICS),
Fausto Rabitti (CNR), and Carlo Meghini (CNR), and is lead by Hans-Jörg
Schek (ETH Zurich). In addition to the attending members, guest talks were
given by Klemens Böhm (GMD/ETHZ) and Moira Norrie (ETH Zurich).
This working group exists in conjunction with working groups in Metadata,
Intellectual Property Rights and Economics, Resource Indexing and Discovery
in a Globally Distributed Digital Library, and Multilingual Information
Access. Recognizing the interoperability issues inherent in each of these
other groups, our group focussed on the architecture which would integrate
these areas. Drawing from a number of sources, including the ARPA I3 Reference
Architecture, the University of Michigan Digital Library agent architecture,
and the Stanford InfoBus architecture, the group proposes an architecture
which broadly divides the system into clients, mediators, and servers.
Within this architecture, four indicative themes of research were identified:
- Information Model: We will investigate a model of information which
includes structure, semantics, and services. The description language based
on the model should have an ontological basis for maximum flexibility and
inter-operability. Another area of research is the dynamic creation of
documents views on databases to facilitate information retrieval and vice-versa.
- Coordination and Control: As much as possible, the mechanisms for providing
digital library services should be transparent to the user. To achieve
this, mediators must be able to autonomously negotiate for digital library
services and make commitments for query and result manipulation. Because
dependencies will exist between mediators and the information they manage,
transactional execution guarantees should be taken into account. A flexible
way of achieving this is via spheres of atomicity and isolation.
- Query Processing: Rich query mani-pulation and processing mechanisms
must be developed. To understand the why and how of a query result, users
should have the possibility to interact with the query processing. This
includes both controlling query formulation and using relevance feedback
techniques. A promising way seems to be the integration of indexing and
retrieval mechanisms developed for multimedia databases with access methods
for traditional databases.
- Implementation Mechanisms: Different collections and DL services are
accessible using different protocols. They accept different query formats
and return results in different formats. Translation or wrapping of these
service-specific aspects should be done as close to the source as possible.
Between mediators, we should use a single, rich, object-oriented communi-cation
mechanism, such as CORBA. In addition to defining these translators and
wrappers, we must also explore how best to utilize the native CORBA services
in order to provide the other capabilities required by the digital library.
The group is currently working on a research report on the mentioned
topics, which will include the presentations given during the Zurich meeting.
Further information, eg about scheduled meetings, will be available on
the public web page of the working group at http://www.si.umich.edu/UMDL/EU_Grant/interop/interop.htm
Please contact:
William Birmingham University of Michigan
E-mail: wpb@eecs.umich.edu
Hans-Jörg Schek ETH Zurich
E-mail: schek@inf.ethz.ch
