Domain Model

• The domain model consists of concepts and concept relationships

Concepts (or Concept Components) were discussed on the previous slide, but what are concept relationships?

• A Concept Relationship is an object
• The concept relationship consists of a unique identifier and attribute/value pairs
• The attribute/value pairs relate two concepts in some way

Some Concept Relationships

• Hypertext link
• Prerequisite
• Inhibitor

Hypertext Link

• The hypertext link is the most common type of relationship. An example of such a link is the next and previous links at the top of this page.

Prerequisite

• The prerequisite relationship means if one concept is prerequisite to another, then the system should somehow discourage the visitation of the second concept before the user visits the first. The actual implementation of how this is accomplished is left up to the developer.
• The prerequisite relationship does not mean that there must be a link from the first concept to the second concept. This relationship simply means that the user should have visited the first concept before visiting the second concept.

Inhibitor

• The inhibitor is a type of relationship in which once a concept has been visited, then the system should discourage it's revisitation. Again, the implementation of this is left up to the developer.

Some approaches to enforcing these relationships were discussed in the previous hypermedia presentation. (e.g. Link hiding, link annotations, link disabling, and link removal)

A Concept Relationship Example