Artifact: Design Subsystem
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A model element which has the semantics of a package (it can contain other model elements) and a class (it has behavior). The behavior of the subsystem is provided by classes or other subsystems it contains. A subsystem realizes one or more interfaces, which define the behavior it can perform. |
| UML representation: | Subsystem |
| Worker: | Designer |
| Optionality: | Optional for simple systems composed only of classes and packages. |
| Reports: | Design-Model Survey, Design Package/Subsystem |
| More information: | Guidelines: Design Subsystem |
Purpose 
The following people use the design subsystem:
- The architect, to encapsulate complex behavior.
- Designers, to encapsulate their design work, and to serve as a logical unit of work.
Design Subsystems are used to encapsulate behavior inside a "package" which is provides explicit and formal interfaces, and which (by convention) does not expose any of its internal contents. It is used as a unit of behavior in the system, which provides the ability to completely encapsulate the interactions of a number of class and/or subsystems. The 'encapsulation' ability of design subsystems is contrasted by that of the Artifact: Design Package, which does not realize interfaces, and may expose contents which are marked 'public'. Packages are used primarily for configuration management and model organization, where subsystems provide additional behavioral semantics.
Properties
Property Name |
Brief Description |
UML Representation |
| name | The name of the subsystem | attribute |
| description | The short description of the role and purpose, or the "theme" of the subsystem. | attribute |
| interfaces | associations to realized interfaces | realization association |
| contents | aggregation associations ton contained model elements | aggregation association |
| dependencies | dependency associations to interfaces or packages on which the subsystem depends | dependency |
Timing
The design subsystem is created during Activity: Architectural Design, and updated during Activity: Subsystem Design.
Responsibility
A Designer is responsible for the integrity of the design subsystem, ensuring that:
- The subsystem encapsulates its contents, only exposing contained behavior through interfaces it realizes.
- The operations of the interfaces the Subsystem realizes are distributed to contained classes or subsystems.
- The subsystem properly implements its interfaces.
