Wrapping Architectures for Long-Term Sustainability

The long-term sustainability of any system depends essentially on one phenomenon: the ability of the original architecture to support system changes that reflect the changes in its operational environment over the long-term, including changes in that architecture. These long-term changes must respond to both new requirements imposed from above, and new or improved technologies provided from below. In this paper, we show how our wrapping infrastructure provides a mechanism by which a constructed complex system can track relevant environmental changes and plan the necessary software adjustments. We expect such a system to examine models of its environment, and its behavior in the environment, to check them continually against the specifications that define the designers' assumptions about the use of the system, so it can call for help when they are violated. We offer our wrapping approach to infrastructure as a mechanism that has been shown to have the necessary flexibility in some contexts. In a wrapping-based system, most of the design decisions are visible in the resource definitions and their meta-knowledge descriptions, with the associated context and usage assumptions. That explicit knowledge is available to the system and the maintainers, which makes it much easier for the system to decide that changes are needed, and much easier for the developers to change it