An Ensemble represents an Event, Person, Thing, Place or other concept in a Data Vault model. The Ensemble is the general equivalent of the Entity in traditional relational modeling modeling (such as 3rd normal form - 3NF), and also similar to the Concept on conceptual modeling and can also be recognized, in general, as a Dimension in dimensional modeling.
An Ensemble is based on a Core Business Concept (CBC) meaning an event, person, thing, place or other concept that is commonly used and understood by business users. This is specifically not a technical construct nor is it a generalized or abstracted concept.
The Ensemble Constructs
While Ensembles are designed to reflect specific instances of CBCs in the business, they are modeled using the Unified Decomposition approach. This means that the single instance is represented by more than one table in the model.
Instance of the CBC
As with all concepts, entities, dimensions, tables (logical and physical), one common requirement is the need to uniquely identify a specific instance. In modeling and in technical terms this is a form of key (as with a primary key - PK), identifier (ID), or other. In Data Vault modeling, this is an Ensemble Identifier. The Hub is the wrapper around this identifier; a table that contains and is defined solely by this unique identifier.
Natural Business Relationship
Any business map, conceptual model, logical model, data model, graph model, etc. is based on concepts and relationships. In all ensemble methods, these relationships reflect the natural business relationship (NBR) between a set of CBCs (2 or more). The Link construct captures and communicates unique, specific NBRs. They do not contain any context and do not have their own identity.
Context & History of the CBC
A set of one to many Satellites captures the context, the descriptive information, of the CBC. Satellites are temporal constructs that capture all of the history concerning a specific CBC. Satellites are designed by logical groupings of context attributes. A satellite does not have it's own identity; it is attached to one (and only one) Hub in order to describe it. Satellites do not maintain any relationships to other concepts in the model.
Working with Ensembles
Ensembles are based on the Core Business Concepts of the organization. To identify these CBCs, modelers and architects need to turn to the business representatives within the organization. A recommended approach to perform this function is to leverage an Ensemble Business Mapping workshop. These workshops will result in a business-driven Ensemble Logical Model (ELM).