Elements of an Ontology
An ontology captures individual entities, the relationship between that entity with other entities, and the behaviour of the entity. An entity can have characteristics (attributes) and states. For instance, a car (an entity) can be driven (the relationship) by a driver (another entity). The speed at which the car travels can be increased by the accelarator, and reduced by the brakes (the behaviour). The car can be at rest (a state) or in motion (another state). The car has a color (an attribute) and a height (an attribute), width (another attribute), and length (another attribute), which make up its dimensions (a set of attributes consisting of length, width, and height). This section provides some guidelines on creating ontologies.
1. Entities and the Business System
The operational focus of a business system means that some entities are of greater interest than others. In Section ?, the ontological depth of 2 microworlds, the Furniture Store and the Warehouse, identified the relevant perspectives in each business organization, and then confined the ontologies to a sufficiently applicable level. The effectiveness of an ontology for a business system must identify the entities that are of interest in business domain, and the amount of detail that must be understood about the entity for the system to function effectively.
2. Tangible and Intangible Entities
Some of the entities that are used by business systems are easy to identify, as they physically exist in the real world. Other entities, such as Business Services, Orders, Mandates, Transactions, Requests, etc. do not exist physically in the real world. Despite their questionable level of existence, intangible entities sometimes form the foundations of business systems. Orders, for instance, are an intangible entity. There can be physical entities that represent the Order, such as a Purchase Order document, but the Order itself is an intangible entity. The Order is used as the primary interface between a Customer and a Business, and it is used as an instrument to initiate, fulfill, and maintain the provision of goods from the Business to the Customer.
