Digital Library Implementation, Architectural Principles

1. Complex information resources are best represented by networks of related data objects, each of which instantiates a component of the content that is appropriate to the medium and context of that component, and records its relationship to other objects. It quickly becomes clear that data design schemes for digital libraries that include all kinds of data must account for human conceptions of information resources that appear to be singular but are made up of many components of data in different media for which different management schemes and different delivery behaviors are required.

2.Every data object will be tied directly or indirectly to a primary collection object. Every object that is added to the UVA digital library must be part of a primary collection. These primary collections have their own objects that describe the collection as a whole and, if applicable, have a full-text index of XML files related to the collection associated with them. These primary collection objects should be thought of as the root nodes for networks of related objects, ensuring that every object in the digital library is a part of some network. Whenever some new type of collection is being added, a new primary collection object would be created. These top-level collection objects are implicitly child nodes of the digital library itself.

3. Each data object will always have three metadata datastreams: one for descriptive metadata, where the intellectual content of the object as a whole is described; one for administrative metadatadata that describes the history of the digital object, policies associated with the use of the data and technical information about the data object; and one for kinship metadata that organizes the relationship information, containing the PIDs of related objects and information about the nature of the relationship. This standardization of metadata ensures that there is a set of protocols that are globally applicable to the digital library. Both users and managers of the digital library will always have one predictable way to discover and investigate an object regardless of content type or the medium through which it is expressed.

4. Disseminators will be used to standardize access to objects wherever possible. A key feature of the UVA digital library architecture is that disseminators on all objects will fall into one of three categories: default behavior definitions to which every object in the digital library must subscribe; collection-specific behavior definitions to which every object of a certain primary collection must subscribe; and special behavior definitions that provide specialized access to a subset of objects in a given collection.