The Structure of Concern Project compares many theoretical models from many disciplines to the Adizes PAEI model, arguing that they must all be reflecting the same underlying phenomenon. One concern structure model is described below.
In large computer networks, it is hard to balance processing resources for the many tasks that are concurrently being run. Constraints and priorities change constantly. Somehow the different parts of the system must understand the implications of those changes for their own processes, plus change their own interactions with other processes in real time to fit system conditions.
Bose and Matthews (2000) argue that any self-adaptive software system that responds to changing preferences and constraints must exercise four major capabilities: detecting changes, knowing the adaptive degrees of freedom, reasoning towards adaptive decisions and integrating changes. These are described below in PAEI order:
P - Knowing the space of adaptations: The system must know what self-changes it can choose from to reduce deviations. It needs to know the dimensions of this task, the favored tactics and preferred values for key variables. These are things the adaptive system can do.
A - Reasoning for adaptation decision: Explicit planning may be needed. The system should be able to reason and make commitments on the self-changes and revised goals.
E - Detecting change in context or needs: The system must monitor its behavior and detect deviations from its commitments or the presence of new opportunities. It should be able to accept new needs from external sources and evaluate for deviations with respect to current commitments.
I – Integrating the change: Coordination changes may have to be packaged, assembled and configured to insert them dependably into the current system without excessively disrupting ongoing behaviors.
Bose and Mattews then describe a three-layer multi-agent architecture to tackle this problem. Their model covers the P, E and I elements of the Adizes model, with A-style agents playing important supporting roles within the P and E layers.
