Part I of this book is general, drawing examples from the panoply of digital library innovation and implementation around the globe. But this is a practical book about how to build a digital library. Rather than attempting a high-level survey of the many different software products that are available, Part II focuses on a particular system for building digital libraries: the Greenstone Digital Library software from the New Zealand Digital Library Project at the University of Waikato. Almost all of what is presented in Part I can be implemented using the Greenstone toolkit.
Table 1.2 summarizes key features of the Greenstone software. A library can include multiple information collections, each individually designed to meet the needs of users and to take advantage of whatever organizational information is available (or can be provided). A collection comprises several (typically several thousand, or several million) documents. Documents are the fundamental unit from which collections are built; they may have internal structure, alternative representations, and associated files. Documents may contain text, images, sound, or video; collections may include a mixture of document types. Metadata is bibliographic information associated with individual documents.
Each collection provides a uniform interface through which its documents can be accessed, an interface that is designed by the librarian responsible for the collection. Prior to presentation, collections undergo a building process that, once established by the librarian, is completely automatic. This creates all the structures that are used to access the collection. Searching is based on indexes of full text and metadata. Browsing is based on structures built from metadata. When new material appears, it can be fully incorporated into the collection by rebuilding.
To address the exceptionally broad requirements of digital libraries, the Greenstone system is public and extensible. It is issued as free open-source software under the GNU General Public License. It is widely used throughout the developed and developing worlds. Further details, and many examples, can be obtained from www.nzdl.org. Part II of the book describes how to use the software to build digital library collections, customize them to particular requirements, and use Greenstone’s many interoperability features.
