The New Zealand Digital Library

74 Computer A s the capabilities of distributed digital libraries increase, managing organizational and software complexity becomes a key issue. How can collections and indexes be updated without impacting queries currently in progress? When users can communicate with the system in different natural languages, how can software cope with the display of various versions of text? With multimedia collections, how can a uniform, extensible software framework accommodate different kinds of search engines required to search various media types? How can the system handle several user-interface clients for the same collections? How do these clients learn about new collections created in different physical locations? We have developed a software structure that successfully manages this complexity in our own digital library. It dynamically handles additions of new collections in different locations without requiring a centralized list. Its novel, flexible macro language manages interfaces to many collections in many languages, and the structure allows development of experimental user interfaces. It accommodates radically different search engines within a uniform structure and communication protocol. The architecture has met our goal of minimizing maintenance while allowing our digital library to easily expand its offerings.