B.1.5:4.4 - Expose The Composite Method Interface

The candidate Method’s reusable action includes a boundary decision for each interaction:

• exposed: a caller system may rely on the interaction as part of the whole Method;
• forwarded: a caller system may address an internal submethod interaction through a declared designation or adapter;
• encapsulated: the interaction is internal and cannot be relied on from outside the whole Method.

An exposure decision contributes to Method identity whenever changing it changes the reusable action or its admissible boundary. That identity consequence does not wait for an outside party to rely on the Method. A named caller, planner, auditor, substituting-method selection use, or assurance use instead determines when the decision must be stated explicitly or published for reuse. Name the interaction, precondition, result or preserved condition, failure route, and any adapter needed for each exposed or forwarded case.