TGFR Consulting LLC The operational risk analysis forms the basis for the use case development. During the operational and functional analysis portion of the risk analysis, use cases have been identified and linked to the failure modes. This analysis needs to be formalized into use cases that can be translated into requirements. In most definitions of a use case (Cockburn, 1998), the following elements are initially identified
Use Case Elements
| Use Case Element | Description |
|---|---|
| Use Case Name | Descriptive name for the use case |
| Scope | What is the scope of the use case. This should relate back to the mission or therapy phase. |
| Level | This should be either Summary, Primary task (phase), Sub-function (a sub-case within the primary task) |
| Priority | Within this context this should be related to the maximum severity of the associated risk |
| Frequency | This should be linked to the α as defined in the risk analysis |
| Trigger | What initiates the use case |
| Main Success Scenario | What is the main path for the use case, often referred to as the “happy path” in that errors and issues are not addressed |
| Extensions | Additions to the use case, usually in the case of issues or failure modes. |
| Sub-Variations | Explicit differentiated changes to the use case |
The operational phase risk analysis links failures to use cases. The following figure illustrates how the elements of the risk analysis integrate with the workflow in the development of use cases
The development of the use cases should consider the following
- Completeness – Main Success Scenarios may link to one or multiple functions, as identified in the risk analysis, depending upon the granularity of the use cases development. Simpler systems may require fewer use cases, but all Main Success Scenarios must address all phases and associated functions.
- Extensions – Each Use Case must include extensions for all of the failure modes associated with the functions included.
- Linkage – Each use case must include information that links the Use Case to the mitigations associated with the failure modes encompassed in the extensions.