Exactly the information your subcontractor needs: DeSyRe - Decomposing system requirements

In software systems development, the increasing size and complexity of systems is handled by decomposition. Companies additionally sign up different subcontractors for subsystems. For distributed development and smooth integration, a major challenge is to deduce subsystem specifications from system specifications in order to deliver them to the subcontractors. Missing information within the subsystem requirements is the pitfall for successful distributed development, so that either the subsystem requirements do not fulfill the overall system requirements completely, or there is a mismatch between subsystems during integration due to inconsistencies between the specifications for the respective subsystems. The objective is to find a good way for the requirements engineer to deduce subsystem requirements from system requirements. The contribution of this paper is an approach to systematically derive subsystem requirements from system requirements by use of assumption / guarantee reasoning and decomposition patterns. Thereby, the approach ensures completeness of the subsystem requirements with respect to the given system requirements. The approach is evaluated by means of case studies concerning applicability and usefulness. Keywords-Requirements, Subsystem, Decomposition, Refinement, Subcontractor