Scope
Compared
- How each represents entities, relationships and keys
- Storage structure versus operating model
- What each is fundamentally for
Not compared
- Specific database engines or SQL/DDL dialects
- Normalization and denormalization choices
- Physical storage and indexing
Terminology mapping
| OCOM | Data Model | Equivalent |
|---|---|---|
| Object | Entity / Table | Partial |
| Identity | Primary key | Similar |
| Relationship | Foreign key / Association | Similar |
| Reference | Foreign key | Similar |
| Metadata | Column / Attribute | Similar |
| Classification | Type / Subtype table | Partial |
| Constraint | Constraint / Check | Similar |
| Ownership | — | None |
| Lifecycle | — | None |
| Evidence | — | None |
Conceptual differences
| Aspect | OCOM | Data Model |
|---|---|---|
| Purpose | Governs operational objects and their reality | Structures data for storage and query |
| Nature | An operating model with rules and conformance | A schema for a database |
| Level | Implementation-independent | Tied to a storage paradigm |
| Governance | First-class: ownership, policy, contract | Not defined by the model |
| Lifecycle | First-class: objects have states over time | Ad hoc row status at best |
Concept coverage
| Concept | OCOM | Data Model |
|---|---|---|
| Identity | Covered | Covered |
| Relationships | Covered | Covered |
| Metadata | Covered | Covered |
| Constraints | Covered | Covered |
| Persistence | Partial | Covered |
| Lifecycle | Covered | Out of scope |
| Governance | Partial | Out of scope |
| Ownership | Covered | Out of scope |
| Provenance / Evidence | Partial | Out of scope |
Three OCOM cells read Partial rather than Covered (Persistence, Governance, Provenance / Evidence), and the reason for each is recorded in the specification's own register: Persistence is Partial because OCOM defines no storage form; a data model is one storage projection of the objects OCOM governs; Governance is a Core Characteristic of every Object that no document defines as one (AO-023); Evidence has no Meta, Models or Language definition, its Definition being reserved for a future version (AO-021). Workflow and Event are defined normatively at the Models tier and carry no Core Vocabulary term record.
Covered: the model defines the concept explicitly. Partial: the concept appears indirectly or by convention. Out of scope: the model does not set out to describe it; a boundary, not a deficiency.
Interoperability
- An OCOM model may be persisted in a relational or other data model; the data model is one storage projection of the objects OCOM governs.
- A data model may store OCOM objects and relationships, but does not itself provide governance, lifecycle or ownership.
- The recommended composition is to design the governed objects in OCOM and persist them in a data model, not to treat the schema as the operating model.
References
- OCOM Object
- OCOM Identity
- OCOM Relationship
- Entity-relationship and relational data models