Hypertext Conceptual Design
ER not suitable for modeling hypertext
- no directed paths (links)
- hypertext access paths not modeled (web page hierarchies)
- no way to group related entities into a singe “macroentity”
Navigational Conceptual Model (NCM) describes these conceptual properties of hypertext
- macroentities (groups of related ER entites) model hypertext nodes
- associated with simple (atomic) or complex (structured) attributes, either mono- or multi-valued
- directed relationships model links (may be bidirectional)
- union nodes model link targets that can be of different types
- aggregations model hierarchical access paths
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