This document is a description of the requirements engineering and the design of a common system architecture for the RESONANCE Framework. The RESONANCE Framework is a software framework that provides means for developing Resource Managers (RMs), Customer Energy Managers (CEMs) and their aggregation solutions in a plug-and-play manner. It consists of independent catalogues for RMs, CEMs, and aggregation services and provides Data and Service Marketplaces with Configuration and Deployment Tools that enable the distribution and tailoring of Demand-Side Flexibility Management (DSFM) solutions.