Purpose of the Catalog System

Arboreal's catalog system allows for abstract URIs in a document to be mapped to real URIs. The abstract URI functions as a permanent identifier for an object. This strategy offers two benefits:

1. It allows for stable references to objects.

2. It allows a user to switch between several instantiations of the same object.

Since the locators used in the Archimedes project are valid URIs, they may function as abstract URIs.

Example 1: A user creates a terminology file that contains hundreds of links to the primary source document with locator 036.xml. The catalog system allows for the links in the terminology file to be interpreted properly whether the text is instantiated on the user's machine as

file:///Users/mjschief/monte_mecha_01_la_1577.xml

or on the network as

http://archimedes.fas.harvard.edu/texts/monte.xml

Example 2: The user wishes to switch between a series of page images on her local machine and an equivalent series stored on a Digilib Image Server. She can accomplish the switch by loading a new catalog file that remaps the abstract URIs for the page images.