Development in rural European areas face many barriers. The Collaboration@Rural (C@R) EU project aims to remove these barriers through Collaborative Technologies adopted among Rural Living Labs across Europe, and to substantially contribute to the definition of a user-centric Open Collaborative Architecture. The paper presents the threefold C@R Open Service Oriented Architecture approach in System, Software Architecture and Practical Implementation levels. We show that collaborative functions can be orchestrated and instantiated in a tailored process using a service broker that can register and manage them. By introducing control and data planes and a domain concept, the C@R architecture easily addresses different business models in a more natural way compared to other software platforms or service architectures. We also illustrate how the Software Architecture principles and specific components discussed are instantiated in the Spanish and South African Rural Living Labs.