Mediators stand as a core architectural paradigm for today's and future systems that increasingly need to be connected. The mediator concept has been used to cope with many heterogeneity dimensions. Still, a key challenge for today's systems architectures is to embed the necessary support for automated mediation, i.e., the connector concept needs to evolve towards the one of mediating connector. In this paper, we introduce a framework to formalize mediating connectors. The proposed characterization paves the way for automated reasoning about protocol matching and mapping, and thus for the dynamic synthesis of mediating connectors to enable eternal networked systems, which we investigate as part of the CONNECT European project