Artifact: Implementation
Subsystem
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| An Implementation Subsystem is a set of Implementation Elements. Implementation Subsystems structure the Implementation Model by dividing it into smaller parts that can be separately integrated and tested. | |
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Part Of Implementation Model
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| Role: | Implementer | |
| Optionality/Occurrence: | Recommended. Elaboration phase. | |
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| Examples: |
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| UML Representation: | Package in the implementation model, either its top-level package, or stereotyped as <<implementation subsystem>>. | |
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| Input to Activities:
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Purpose
The following people will use the implementation subsystem:
- Software architects use it to structure the implementation model into parts that can be separately integrated and tested.
- Those who design the next version of the system use it to understand the structure of the implementation model.
- Implementers of other parts of the system use it to understand how their functionality can be used.
- Those who test the subsystem use it to plan testing activities.
- The project manager uses it as a basis for allocating the implementation work.
The implementation subsystem is the physical analogue of the design package. The implementation model and the implementation subsystems are initially defined in the implementation view, and so are of primary importance at development time.
Properties
Property Name | Brief Description | UML Representation |
|---|---|---|
| Name | The name of the subsystem | The attribute "Name" on model element |
| Brief Description | A brief description of the role and purpose of the subsystem | Tagged value, of type "short text" |
| Implementation Elements | The Implementation Elements directly contained in the subsystem, including files and directories. | Owned via the meta-aggregation "owns" |
| Relationships | The relationships directly contained in the subsystem | - " - |
| Diagrams | The diagrams directly contained in the subsystem | - " - |
| Implementation Subsystems | The subsystems directly contained in the subsystem | - " - |
| Import Dependencies | The import dependencies from the subsystem to other subsystems | Owned by an enclosing subsystem, via the meta-aggregation "owns" |
Timing
The software architect defines the subsystems during Elaboration, and allocates them to individuals or teams. This is done before class implementation is started, and thus enables parallel development of subsystems.
Responsibility
An implementer is responsible for the subsystem, and ensures that:
- The subsystem fulfills the requirements made on it.
- The import dependencies originating from the subsystem are described so that the effect of future changes can be estimated.
- The contents of the subsystem, including files, directories, and nested implementation subsystems, form a cohesive part of the implementation suitable for separate integration and test.
- That the subsystem is kept consistent with the corresponding part of the design model.
The implementer responsible for an implementation subsystem is also responsible for the public (visible) elements of the subsystem.
It is recommended that the implementer responsible for an implementation subsystem is also responsible for all its contained elements; for more information see Artifact: Implementation Element.
If a team of implementers develops an implementation subsystem, one of the team members should be responsible for the subsystem.
Tailoring
It is recommended that you use implementation subsystems. You have to decide how to map packages in design to subsystems and directories in implementation. You have to decide how many levels of subsystems you need.
