From Modular to Distributed Open Architectures: A Unified Decision Framework

Abstract

This paper introduces a conceptual, yet quantifiable, architecture framework by extending the notion of system modularity in its broadest sense. Acknowledging that modularity is not a binary feature and comes in various types and levels, the proposed framework introduces higher levels of modularity that naturally incorporate decentralized architecture on the one hand and autonomy in agents and subsystems on the other. This makes the framework suitable for modularity decisions in Systems of Systems and for analyzing the impact of modularity on broader surrounding ecosystems. The stages of modularity in the proposed framework are naturally aligned with the level of variations and uncertainty in the system and its environment, a relationship that is central to the benefits of modularity. The conceptual framework is complemented with a decision layer that makes it suitable to be used as a computational architecture decision tool to determine the appropriate stage and level of modularity of a system, for a given profile of variations and uncertainties in its environment. We further argue that the fundamental systemic driving forces and trade-offs of moving from monolithic to distributed architecture are essentially similar to those for moving from integral to modular architectures. The spectrum, in conjunction with the decision layer, could guide system architects when selecting appropriate parameters and building a system-specific computational tool from a combination of existing tools and techniques.To demonstrate the applicability of the framework, a case for fractionated satellite systems based on a simplified demo of the DARPA F 6 program is presented where the value of transition from a monolithic architecture to a fractionated architecture, as two consecutive levels of modularity in the proposed spectrum, is calculated and ranges of parameters where fractionation increases systems value are determined.

Distributed or Monolithic? A Computational Architecture Decision Framework

“…As a unified framework, we employ a value-based decision making framework developed in our previous work [9]. This framework is based on a systems architecture spectrum that covers a wide range of modularity/distributed architecture in complex systems and classifies the degree of modularity into five stages, as shown in Fig.…”

An Empirical Case Study of Problem Structuring in the Use of Generic Architectures

“…Surrounding the idea that generic or modular architecture can deliver ownership benefits, Broniatowski & Moses (2016) propose metrics to highlight relative pros and cons of decisions regarding a type of generic architecture to implement. Heydari et al (2016) propose a decisionmaking framework to support decisions on the extent of modularity sought in transitioning from monolithic towards modular architecture. Szajnfarber et al (2015) provide model-based insights for implementing technology transitions to in-service military systems, and find that limited capability enhancements delivered quickly can be more beneficial than delaying and implementing a more significant upgrade as part of a more substantial upgrade activity.…”

Distributed Resource Management in Systems of Systems: An Architecture Perspective

“…Several frameworks have been developed for the architecture of SoSs [Morganwalp and Sage ; Maier ; Rhodes, Ross, and Nightingale ]. In this paper, we will focus on using the system's connectivity structure to represent its architecture and will use the framework developed in our previous work [Heydari, Mosleh, and Dalili ; Mosleh, Dalili, and Heydari ]. This framework is capable of describing many levels of system connectedness, from fully integral monolithic systems to distributed, adaptive, and dynamic systems.…”

“…The five levels of modularity in the systems architecture framework, developed in our previous work [Heydari et al., ; Mosleh et al., ], form a spectrum in which increased modularity improves system responsiveness to the operating environment. The level of modularity, together with systems flexibility, increases from M 0 to M 4 .…”