'Collection' Template Overview

Introduction

The collection template provides a mechinism for grouping, or collecting elements together. The collections are represented by arcs, or relations, that link two elements. Figure 1 shows a simple illustration of two collections.

Collections are distinguished by the following properties :

• Represented by a set of arcs, or relations
• Each arc relates two entities - a 'left' and a 'right' entity.
• The entities at either end of a relation can be either a contact record, a catalogue item or a catalogue node
• Each arc belongs to one of a number of classes of arc - named by the application
• There can be at most one arc of a specific class linking two distinct elements
• Data can be stored on each arc. This allows an application to record 'why' two entities are related rather than just that they are related (person X is related to book J because he is the author. Person Y is related to the same book because she is the editor)
• Applications can traverse arcs in either direction (left->right andleft<-right)

Operations provided by the rb.collection object allow classes of arc to be created, deleted and modified. A a class, or type, must be created before arcs of that type can be created.