Task: Gather Subsystem Specification Data |
|
Purpose
The purpose of this task is to colocate all the data being passed to the subsystem teams to ensure that the subsystem
have a clear understanding of what they need to produce, the logical interfaces they must support, the functionality
they must provide, the requirements they must meet, and the qualities of service that they must sustain.
|
Relationships
Roles | Primary Performer:
| Additional Performers:
|
Inputs | Mandatory:
| Optional:
|
Outputs |
|
Main Description
It is expected that the organization of the model(s) used by the system engineering staff will naturally colocate much
of the necessary data. However, there is usually other data - which might be stored in non-model files and tool formats
- that must be provided to the subsystem teams to ensure they build the right thing. This information includes
-
Requirements allocated to the subsystem with links to requirements repositories
-
Use case, scenario, and state data defining subsystem functionality
-
Constraints and quality of service information, including parameters such as heat, weight, power, speed, and so on
-
(Logical) operational contracts including
-
-
function or service name
-
data pass in or out
-
pre- and post-conditions
-
quality of service constraints
-
Algorithmic and computational functionality
-
(Logical) interfaces among subsystems and between subsystems and system actors
-
Architectural structure into which the subsystem must fit
In general, if SysML or UML is used as the primary method for capturing information, it is recommended that the system
engineering model contain all this information in one package per subsystem and hand off a package to each relevant
subsystem (there may be nested packages). If there is significant data external to the model, then a conformance list
should provide a list of all data to be passed.
|
Steps
Create new subsystem model package within systems model
Collect relevant pieces of the systems model
Move the relevant specification information into the subsystem package. This typically includes:
-
(Logical) operation contracts and service specifications
-
State machines
-
Subsystem level use cases
-
Activity diagrams
-
Sequence diagrams
-
Requirements traceability links
|
Review Handoff Specification Data
Examine the specification data handed off from systems engineering to ensure that it is complete, accurate, adequate, and
clear. Ensure that it meets the needs of the subsystem team as a basis on which to perform downstream Engineering
and construction. |
|
Key Considerations
Key considerations include:
-
Completeness
-
Accuracy
-
Ease of access by the subsystem teams
-
Clarity
If relevant, be sure to include quality of service and dependability expectations as well.
It is also important not to overspecify the internal structure of the subsystem, a common error. The external behavior,
performance and dependability should be specified by the handoff system data but the internal structure and
internal-only interfaces should not.
|
Licensed Materials - Property of IBM
© Copyright IBM Corp. 1987, 2012. All Rights Reserved.
|
|