Composition

To capture modularity in design we compose a framework (C-FBS) out of several FBS frameworks. We consider the design of the models M, M¹, and M², where the latter two are models for components of model M. All models have their own design process, FBS, FBS¹, and FBS², each of which can be described by the function-behaviour-structure framework for design.

The three design processes can be integrated, so that the processes that play a role in the composition become clear and immediate feedback can take place between the frameworks. The figure below shows the integration of the three design processes.

Composition in the FBS framework

Below we describe the changes in processes because of this integration.

Decomposition

Once an acceptable structure S is determined, the design for several of the components can be done separately. For the design of the components, the functions for each of the components have to be determined.

function decomposition ({F, D} → Fⁱ): As the structure S consists of the components and their interaction for model M, the description D contains the functionality for the components. Furthermore, F may contain functionality not contained in D, but that is to be taken into account in the design of the components.

Reformulation

Each FBS framework contains the normal reformulation processes. However, reformulations in the frameworks FBS¹ and FBS² have to be such that the elements stay in accordance with the function F and description D of the FBS framework. When that is not possible anymore, the design for the component has to be rejected and one of the following reformulation processes has to take place.

structure reformulation (Sⁱ → S): When reformulation of Sⁱ is not possible anymore to obtain an acceptable structure for the component, reformulation of S has to take place.
function reformulation (Fⁱ → F): When a reformulation of the part of Fⁱ that originates from F is necessary, this has to be done through reformulation of F directly in order to keep a consistent description of the functionality throughout the C-FBS framework.

Integration

Once the design of a component is complete it has to be integrated with the overall design. The following processes describe the integration of designs.

documentation integration ({Dⁱ} → D): The description for each of the components is integrated with the description for the whole object.