Scenario T1 - A requirement is elaborated

Motivation

This scenario addresses the progressive development of requirements and design artefacts, and can be considered to represent the ‘left leg of the V'. This process is seldom completed in one iteration, so there is a need to support the process of development as well as representing the end state.

Pre-conditions

A requirement exists that is to be elaborated. This requirement is referred to as the 'root requirement'.

Scenario

1. Alternative elaboration strategies are considered and (optionally) recorded. If recorded, this may be:
   1. as a separate argument artefact that is linked to the root requirement, or
   2. as a property of the root requirement.
2. Existing lower level requirements are reviewed to identify candidates that could potentially satisfy the root requirement.
3. Any issues (missing information, risks, etc) are identified, recorded, and linked to the root requirement (or argument artefact, if it exists).
4. Any supporting evidence for the elaboration strategy (reference documents, models, etc) is identified, recorded, and linked to the root requirement (or argument artefact, if it exists).
5. A final elaboration strategy is chosen and (optionally) recorded in the argument.
6. Existing lower level requirements that support the chosen elaboration strategy are linked to the root requirement.
7. New requirements needed to support the chosen elaboration strategy are created and linked to the root requirement.
8. Outstanding issues are 'worked' until they are closed.
   1. Closure of issues may require changes to any artefact (requirements, arguments, supporting evidence), creation or deletion of artefacts, or changes to traceability.
   2. Issue artefacts should include a status property.

Post-conditions

The root requirement is supported by a collection of linked lower-level requirements. Rationale for the elaboration is (optionally) recorded, and supported by relevant evidence. Issues affecting completion of the elaboration are closed.

Notes

This scenario describes a variety of artefacts (requirements, arguments, supporting evidence, issues) that are linked in some way. The nature of these links differs depending upon the artefacts that are linked together (e.g. requirements are linked to other requirements via 'satisifies' relationships, issues are linked to requirements via 'impacts' relationships). This scenario would therefore benefit from explicit typing of links.

-- SimonWills - 05 Feb 2010