  The field of digital libraries (DLs) coalesced in 1994: the first digital
library conferences were held that year, awareness of the World Wide Web was
accelerating, and the National Science Foundation awarded $24 Million (U.S.)
for the Digital Library Initiative (DLI). In this paper we examine the state of
the DL domain after a decade of activity by applying social network analysis to
the co-authorship network of the past ACM, IEEE, and joint ACM/IEEE digital
library conferences. We base our analysis on a common binary undirectional
network model to represent the co-authorship network, and from it we extract
several established network measures. We also introduce a weighted directional
network model to represent the co-authorship network, for which we define
$AuthorRank$ as an indicator of the impact of an individual author in the
network. The results are validated against conference program committee members
in the same period. The results show clear advantages of PageRank and
AuthorRank over degree, closeness and betweenness centrality metrics. We also
investigate the amount and nature of international participation in Joint
Conference on Digital Libraries (JCDL).
