Dusan G. Lysy

Level of modularity and different levels of system granularity

All complex system development projects involve analysis of the system architecture. Thus far it has been assumed that there is some correct system decomposition that can be used in the architectural analysis without consideration of the sensitivity of the results to the chosen level of decomposition. We represent 88 idealized system architectures and a real complex system as a design structure matrix at two different levels of decomposition. We analyze these architectures for their degree of modularity. We find that the degree of modularity can vary for the same system when the system is represented at the two different levels of granularity. For example, the printing system used in the case study is considered slightly integral at a higher level of decomposition and quite modular at a lower level of decomposition. We further find that even though the overall results can be different depending on the level of decomposition, the direction of change toward more modular or more integral can be calculated the same regardless of the level of decomposition. We conclude that the level of decomposition can distort the results of architectural analysis and care must be taken in defining the system decomposition for any analysis.

Comparative analysis of coupling modularity metrics

Modular design has become a widely accepted developmental strategy to create products and systems that can be easily manufactured, upgraded and maintained. In order to achieve these benefits through improvement of a systems modularity, it must be measured. An ideal measure ought to capture modularity while being independent of other architectural factors such as size, system coupling density or the number of modules. In this work, we review past research on modularity measures. Eight modularity measures are selected for a detailed analysis. We use a design of experiments approach to analyse which metrics best measure the degree of modularity independent of other irrelevant factors. To do this, we conduct a factorial analysis of 24 canonical architectures with idealised modularity, including precisely integral, modular and bus architectures. We find that most measures produce inconsistent results, especially if the system architecture contains a bus or modules with loose internal coupling. We identify the metrics that are able to capture the degree of modularity in the most consistent manner.

Architectural Decomposition: The Role of Granularity and Decomposition Viewpoint

Before any platform development, one must create the representation of the products’ architectures. Typically, one would start by decomposing the existing or proposed systems into smaller subsystems or modules. This is a critical step since the remainder of the platform development will depend on the choices made at the decomposition phase. This chapter will discuss how to decompose a product architecture. Specifically we will address the decomposition choices such as level of granularity and different decomposition viewpoints and how they affect the final resulting architecture.

Level of modularity at different levels of system granularity

All system development projects involve analysis of the system architecture. However, it has been assumed t hus far that there is some correct system decomposition that can be used in the architectural analysis. The sensitivity of the results to the chosen level of decomposition has not been consider ed. We represent forty eight idealized system architecture s and a real complex system as a Design Structure Matrix at two different levels of decomposition. We analyze these architect ures for their degree of modularity. We find that the degree of modularity can vary for the same system when the system is represented at the two different levels of granular ity. For example, the printing system used in the case study is considered slightly integral at a higher level of d ecomposition and quite modular at a lower level of decomposition . We further find that even though the overall results c an be different depending on the level of decomposition, the direct ion of change toward more modular or more integral can be calculated the same regardless of the level of decomposition. Level of decomposition can distort the results of architectu ral analysis and care must be taken in defining the system decomposition for any analysis. OBJECTIVE Architectural decomposition is a key part of comple x system management. Architectural decomposition, division of a complex system into smaller subsystems, is a standa rd first step in most complex system analysis. The terms decomposition, system hierarchy, and level of granularity are used throughout the systems engineering literature, but what is lac king is the analysis of how the decomposition, or level of gran ularity, affects the results and thus the conclusions of the architectural analysis. In fact, there is no literature that show s empirical or theoretical work on how to properly decompose or define the level of granularity for architectural analysis, su ch as determination of level of system modularity. This is especially problematic in complex system development, as opposed to simple product development, since complex systems can have multiple possible levels of granularity. The term l evel of granularity in this paper is used to describe the “ grain size” i.e. the size and the detail of the system elements afte r system decomposition. To better illustrate the concept of granularity, Figure 1 shows a partial hierarchical decomposition of a vehicle system as well as three consecutive levels of granularity. In Figure 1, it is shown that the grai n size of the system elements decreases as the level of granulari ty increases. In other words, the subsystems elements at a lower level of granularity are more detailed individual smaller su bsystems; whereas at a higher level of granularity those same subsystems form a larger more abstract subsystem. The objectiv e of this paper is to explore level of granularity and specif ically if and how the level of modularity of a complex system is affected by the level of granularity chosen for the architectur al analysis. The specific research questions in this paper are a s follows: Research question 1: Is the level of modularity affected by the level of system granularity? Research question 2: Is a system at a lower level of granularity always either more integral or modular than the sam e system at a higher level of granularity?