Report of the Second Workshop on Very Large Digital Libraries : in conjunction with the European Conference on Digital Libraries Corfu, Greece, 2 October 2009

The mission of the international workshop series on Very Large Digital Libraries (VLDLs) is to provide researchers, practitioners and application developers with a forum fostering a constructive exchange among all key actors in the field of Very Large Digital Libraries. Its long-term and ambitious goal is to discuss the foundations of VLDLs and establish it as a research field on its own, with well-defined areas, models, trends, open problems, and technology. The main outcome of the first VLDL workshop cite{vldl2008} was consolidation of its mission. After several presentations on the papers accepted to the workshop and further demonstrations and long debates by all participants, there was eventual agreement that VLDLs deserve a chapter of their own in computer science research. Experience in the field since the historical beginning of DLs has proven that VLDLs cannot be simply regarded as very large databases storing Digital Library content, as one may be tempted to assess. In fact, as the DELOS Reference Model for Digital Libraries cite{delos} well motivates, DL Systems cannot be approached from the perspective of content management only; the dimensions of user, functionality, policy, quality, and architecture management are equally important. Accordingly, DLs become Very Large DLs (VLDLs) when any one of these aspects reaches a magnitutde that requires specialized technologies. VLDLs are clearly in their early stage of development. For example, interdependencies among the aspects above are still to be identified and studied; the same holds for models and measures for evaluating ``very-largeness'' of given DL systems. In fact, it is not even clear if there are clear enough patterns and best practices that are common in existing DL systems to determine the boundaries of the field or, instead, practical experience is still too much in its infancy. The second VLDL workshop continued such investigations from where the first one left off.