Requirements negotiation for multilayer system components

Current software systems are hybrid in nature. They are built by integrating third party Off-The-Shelf (OTS) components with preexisting legacy and bespoke custom-made software. In such systems, components are usually arranged into layers (e.g., hardware platform, operating systems and database layers, among others) to allow for their operation and interaction. Although several methods have been proposed to support OTS component selection, the truth is that in many cases the process is driven by political and other non-technical aspects, considering components as independent and isolated. Because of this, relevant stakeholder's requirements and concerns, as well as the implications that the selection of a particular component may bring to the system architecture, are simply ignored. In the worst case this may lead to the selection of unsuited or inappropriate components and eventually to miscarried projects, but more often to situations in which projects froze due to lack of stakeholders' agreement in relation to the newly created architectural scenario and some of its emerging requirements. In this paper we address these issues and present a proposal that uses software quality models as framework to support the negotiation of both initial and emerging requirements and the reconciliation of stakeholders' concerns. The approach considers components at different layers of system's architecture. The advantages of the proposal are illustrated with a real case conducted in a banking organization.