The core of the reference model is a generic architecture for
IMMPSs. Following standard architectural models, the building
blocks of the architecture are layers,
components, and connectors.
Layers serve as abstract locations for tasks, processes, or likewise
(system) components.
A component is an objectification of a task, function or computing
process in a real or abstract system. Components are essentially
characterized by their particular input/output behavior. An internal
structure of a component may be given by means of a set of
subcomponents together with input/output relations between these
subcomponents. A connector between two entities enables (directed)
interchange of information between them.
Fig. 3 outlines the IMMPS reference architecture. Its conceptual design reflects a modularization of the generation process into five layers which stand for particular subtasks, and a separation of shared knowledge sources (called experts) from the layers. The layers are named Control, Content, Design, Realization and Presentation Display layer respectively. In addition to their private knowledge, these layers may exploit explicitly encoded knowledge provided by a knowledge server which is composed of four shared knowledge sources: the Application Expert, Context Expert, User Expert and Design Expert.
The following conventions underly Fig. 3 as well as all subsequent figures: Rectangular boxes denote either layers or components which form the internal parts of an IMMPS. Opposed to that, ellipses indicate external entities with which an IMMPS may interact. The interchange of information between components is reflected by arrows. Double arrows indicate bidirectional information flow. Dashed arrows indicate optional interaction channels to external parts. To indicate exchange of information between some internal components of a layer and another entity outside the layer, we use arrows which only point to the interior of the layer but not specifically to one of the subcomponents. Throughout the rest of the paper we adopt ``RM'' as an abbreviation for ``reference architecture/model for IMMPSs'', and we treat references to the RM's layers and components as proper names starting with capital letters.