Key takeaways
- Modeling = technique; Architecture Model = representation of a subject of interest.
- Abstraction = summarized or generalized descriptions of complex content.
- Metamodel = entity types and relationships; Metadata = data describing an entity.
- A viewpoint references model kinds; a view incorporates models.
- The Viewpoint Library sits in the Reference Library.
Modeling and abstracting
Modeling is a technique: building models to represent a subject in a form that supports reasoning, insight, and clarity about its essence. Its result, the Architecture Model, is a representation of a subject of interest, usually smaller, simplified, or more abstract than reality.
Abstraction is a related but different technique: it produces summarized or generalized descriptions of detailed, complex content. Speaking of a 'level of abstraction' also means working at a consistent level of detail, which helps communication and decisions, and lets important issues surface before going into detail.
Metamodel, metadata, and Model Kind
The Metamodel is a model describing the entities used to build an Architecture Description, their characteristics, and their main relationships. It ensures that all architects describe 'Application' or 'Data Entity' in the same way. Metadata are something else: data about data, describing the characteristics of an entity, such as its author or version.
In practice, the metamodel also serves as a reference for modeling tools: for example, it states that an Application can read or update a Data Entity, and which attributes each entity type must carry.
A Model Kind gathers the conventions for one type of modeling. It provides the link with views: a viewpoint references one or more model kinds, and a view incorporates one or more models.
Views and viewpoints
An Architecture View represents a system from the perspective of a set of related concerns. The Architecture Viewpoint is its specification: it sets the conventions for constructing, interpreting, and using that kind of view to address certain concerns. It can be seen as the schema or definition of the view.
Example: for auditors, a team writes a 'compliance' viewpoint stating the concerns addressed, the notation, and the reading rules. The diagrams later produced for the payment system under these rules are views; each incorporates one or more models built according to the referenced model kinds.
- Taxonomy of Architecture Views: the organized collection of all the views relevant to an architecture.
- Viewpoint Library: the viewpoint specifications kept in the Reference Library of the Architecture Repository.
TERMS TO KNOW
The terms, in context.
- Modeling
- Technique of building models to reason about a subject and clarify its essence.
- Architecture Model
- Representation of a subject of interest, often smaller, simplified, or abstract.
- Abstraction
- Technique providing summarized or generalized descriptions of complex content.
- Metamodel
- Model of the entities used to build an Architecture Description, their characteristics, and relationships.
- Metadata
- Data about data, describing the characteristics of an entity.
- Model Kind
- Conventions for one type of modeling.
- Architecture View
- Representation of a system from the perspective of related concerns.
- Architecture Viewpoint
- Specification of the conventions for one kind of view.
- Taxonomy of Architecture Views
- Organized collection of the views relevant to an architecture.
- Viewpoint Library
- Viewpoint specifications kept in the Reference Library.