TABLE OF CONTENTS This chapter describes how allocation relationships are used to map from one model element to other model elements to support behavioral, structural, and other forms of allocation.
Beginning early in systems development, the modeler may need to associate various elements in the system model in abstract, preliminary, and sometimes tentative ways. It may be inappropriate to impose detailed constraints on the solution too early in the development of a system's architecture. Allocation is a mechanism to relate model elements that is typically a prelude to more rigorous relationships that are established through follow-on model refinement. Additional user-defined constraints can augment the allocation relationship to add the necessary rigor as the design progresses. For example, an allocation of functions (e.g., activities) to components may be done early in the design. As the design progresses, additional constraints are defined to ensure that the activity inputs, outputs, and controls are explicitly allocated to component interfaces. With appropriate user-defined constraints, allocation can be used to help enforce specific system development methods to ensure the model's integrity.
Allocation may be appropriate when modeling a system of systems (SoS), knowing that detailed system development and model refinement may be conducted by different teams, and perhaps even different companies. It also provides a mechanism for dealing with legacy system elements that have not been developed using rigorous modeling techniques. In both cases, allocation can be used to formalize constraints, expectations, or assumptions about that particular system element within the context of a broader system...
