2.3.2 An Architecture‐Centric Approach for Systems Design

The most critical requirements for the lifetime value of a system are its non-functional requirements such as reliability, security, maintainability, changeability, etc. These are collectively known as the ‘ilities’ and are typically addressed in system design once the functional architecture has been developed. In this paper we propose the use of architecture-centric design that modifies this standard workflow so that those non-functional requirements, which actually reflect the true business needs, are addressed first. This ensures that the final system better reflects and embodies those architecturally-significant requirements rather than having them addressed secondarily. This is an important change since the ‘ilities’ are systemic properties (properties of the system as a whole) rather than systematic properties (properties of individual components or sub-systems) and are therefore difficult to address once the functional architecture has been determined and the separation of concerns is already somewhat completed. We provide an example of the approach based around a simplified case study of an online, on-board health monitoring system for shipboard gas turbine electricity generators that collects, filters, analyzes, transmits, and mines sensor data from the generators subsystems.