Task: Decompose Activity Diagrams
This task refines the black-box activity diagram that describes the use case functional flow.
Disciplines: System Engineering Requirements
Purpose
To group functional requirements into actions and show how these actions are logically linked together by decomposing the black-box activity diagram.
Relationships
Main Description

There are two general rules to follow when you perform this task:

  • Don't go too deep with the decomposition: the recommendation is no more than two levels below the top level.
  • Homogeneously decompose across all activities.
Steps
Perform a functional decomposition of the coarse-grained system functions
For each high-level system function identified, determine what the system must do to provide the required functions.  Replace the top-level action nodes with actions representing each of the leaf functions.
Determine the sequencing of functions required
Create control flows to sequence the system functions (actions) to generate the required behavior.
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