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This section sets out the justification behind the choice of standards for component or “white-box” use case descriptions.

What is a Component Level Use Case 

A use case defines a contract between an actor and system by describing their dynamic interaction.

By manipulating what is understood by the scope of the system, different actors may be described. This is what differentiates Component Use Cases to black-box use cases (henceforth called UCs). In the former, the scope of the system is a component (or part of an enterprise), in the latter it is the entire enterprise.

Figure 1: showing relationship of system scope to choice of actors

This can be aided by explicitly showing the system boundary “box” in the Use Case model (UCM) – however Rose does not directly support this, so the note should be used.

Who is interested in it

The clue is in the actor of the UCM – which is directly driven by the scope of the system:

Where the scope is GCS, the actor reflects the stakeholders of the system, and are often end users, therefore the main audience of this artefact is for requirements validation. Additionally since the use case describes something end-to-end, enterprise architects, planners and integrator will be also reviewing the document.

Where the scope is a component, the actor is usually another component –– then the stakeholders are really the individuals involved in building the component or interfacing with the component. However this does not mean that the vocabulary should be technical, since these still need to be validated by a broader community.

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[1] Although in the case of security these goals can often be the mitigation of key, named risks.

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This paper has been prepared by Codel Services Ltd to illustrate how structured business modelling can help your organisation. Codel Services Ltd is an IT Consultancy specialising in business modelling. If you would like further information, please contact us at: Deryck Brailsford, Codel Services Ltd, Dale Hill Cottage, Kirby-Le-Soken, Essex CO13 0EN,United Kingdom. Telephone: +44 (0)1255 862354/Mobile: + 44 (0)7710 435227/e-mail: info@codel-services.com