Some organizations create an Enterprise Data Model (EDM) as a stand-alone artifact. In other organizations, it is understood as composed of data models from different perspectives and at different levels of detail, that consistently describe an organization's understanding of data entities, data attributes, and their relationships across the enterprise. An EDM includes both universal (Enterprise-wide Conceptual and Logical Models) and application- or project-specific data models, along with definitions, specifications, mappings and business rules.
Adopting an industry standard model can jumpstart the process of developing an EDM. These models provide a useful guide and references. However, even if an organization starts with a purchased data model, producing enterprise-wide data models requires a significant investment. Work includes defining and documenting an organization's vocabulary, business rules, and business knowledge. Maintaining and enriching an EDM requires an ongoing commitment of time and effort.
An organization that recognizes the need for an EDM must decide how much time and effort it can devote to building and maintaining it. EDMs can be built at different levels of detail, so resource availability will influence initial scope. Over time, as the needs of the enterprise demand, the scope and level of detail captured within an EDM typically expands. Most successful EDMs are built incrementally and iteratively, using layers. This figure shows how different types of models are related and how conceptual models are ultimately linkable to physical application data models. It distinguishes:
A conceptual overview over the enterprise's subject areas
Views of entities and relationships for each subject area
Detailed, partially attributed logical views of these same subject areas
Logical and physical models specific to an application or project
All levels are part of the EDM, and linkages create paths to trace an entity from top to bottom and between models in the same level.
Vertical: Models in each level map to models in other levels. Model lineage is created using these maps. For example, a table or file MobileDevice in a project-specific physical model may link to a MobileDevice entity in the project-specific logical model, a MobileDevice entity in the Product subject area in the Enterprise Logical Model, a Product conceptual entity in the Product Subject Area Model, and to the Product entity in the Enterprise Conceptual Model.
Horizontal: Entities and relationships may appear in multiple models in the same level; entities in logical models centered on one topic may relate to entities in other topics, marked or noted as external to the subject area on the model images. A Product Part entity may appear in the Product subject area models and in the Sales Order, Inventory, and Marketing subject areas, related as external links.
An enterprise data model at all levels is developed suing data modeling techniques.
DAMA Data Management Body of Knowledge 2nd Edition, 2017, Print.