The diversity of today's networking environments, such as wired, wireless, cell-based, or multi-hop, is matched by an equally large amount and heterogeneity of specialized protocols, e.g., overlays, Wi-Fi positioning, MANET routing, cross-layer signaling. However, communication is typically performed with a static set of protocols selected at design time based on simplified assumptions ignoring the environment's heterogeneity. In this paper, we argue that protocols can be orchestrated as software components driven purely by their functionality and the demands of the execution environment. Our end-system protocol framework Adapt bases on extensible ontological models that semantically describe protocol and environment properties. At runtime, each connection receives a custom-tailored protocol stack that Adapt orchestrates from the requirements derived from the application, user, and environment. With this approach, end-systems can reason about the functionality and quality of automatically composed and adapted protocol compounds while remaining open to existing and future protocols.