Artifact: Design Model

	The design model is an object model describing the realization of use cases, and serves as an abstraction of the implementation model and its source code. The design model is used as essential input to activities in implementation and test.
Other Relationships:	Contains Protocol Capsule Use-Case Realization Signal Event Design Subsystem Design Package Interface Design Class Testability Class Test Design
Role:	Software Architect
Optionality/Occurrence:	Required. Elaboration and Construction phases.
Templates and Reports:	Design-Model Survey Use-Case Realization Design Package/Subsystem Class Report
Examples:	Examples Design Model CSPS Rose Model
UML Representation:	Model, stereotyped as «designModel».
More Information:	Concept: Component Guideline: Concurrency Checklist: Design Model Guideline: Design Model Report: Design-Model Survey Guideline: Layering Guideline: Representing Interfaces to External Systems
Purpose Properties Timing Responsibility Tailoring

Input to Activities:  Architectural Analysis Class Design Construct Architectural Proof-of-Concept Database Design Define Testability Elements Describe Distribution Describe the Run-time Architecture Identify Design Elements Identify Design Mechanisms Identify Test Ideas Implement Design Elements Implement Developer Test Incorporate Existing Design Elements Manage Dependencies Review the Design Structure the Implementation Model Subsystem Design Use-Case Analysis Use-Case Design

Output from Activities:  Architectural Analysis Class Design Describe the Run-time Architecture Identify Design Elements Identify Design Mechanisms Incorporate Existing Design Elements Subsystem Design Use-Case Design

Purpose

The design model is an abstraction of the implementation of the system. It is used to conceive as well as document the design of the software system. It is a comprehensive, composite artifact encompassing all design classes, subsystems, packages, collaborations, and the relationships between them.

Properties

Timing

The design model primarily sets the architecture, but is also used as a vehicle for analysis during the elaboration phase. It is then refined by detailed design decisions during the construction phase.

Responsibility

A software architect is responsible for the integrity of the design model, ensuring the following:

• The design model as a whole is correct, consistent, and readable. The design model is correct when it realizes the functionality described in the use-case model, and only this behavior.
• The architecture in the design model fulfills its purpose, including the logical, process, and deployment views. These views are collected in a separate artifact, see Artifact: Software Architecture Document.

Note that the software architect is not responsible for the packages, classes, relationships, use-case realizations, and the diagrams themselves; instead, these are under the corresponding designers and use-case designer's responsibilities.

Tailoring

Decide on the following:

• properties to include
• whether or not any extensions to the Unified Modeling Language (UML) are needed; for example, your project may require additional stereotypes
• the level of formality applied to the model
• tailoring applicable to individual sub-artifacts
• how the model is mapped to the analysis model (see Guidelines: Design Model)
• whether a single model or multiple models will be used
• whether the model will be an abstract specification, a detailed specification, a detailed design, or some combination (see Guidelines: Design Model)
• how the model is mapped to the implementation model (this is very much affected by the decision to use reverse-engineering, code generation, or round-trip engineering); see Guidelines: Mapping from Design to Code

Document tailoring decisions in your project's design guidelines (see Artifact: Project-specific Guidelines) .

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