With the proliferation of smart embedded devices, Cyber Physical Social Computing and Networking systems (CPSCN) are emerging as a next generation of social networks. Unlike traditional Social Networks that run on cloud-based infrastructure, CPSCN systems usually depend on a large number of distributed, heterogeneous devices such as mobile phones, smart vehicles or network access points. These computing resources, which are often referred to as fog computing systems, provide a gateway to the physical world, and thus offer new possibilities for social applications. Unfortunately, building CPSCN systems that leverage fog computing infrastructure is not straightforward. Significant challenges arise from the large scale distribution of computing resources over a wide area, and the dynamic nature of multiple, possibly mobile, hosts. In this paper, we extend our previous work on a Distributed Dataflow programming model and propose an application platform for realising CPSCN systems. A key aspect of our work is the development of an exogenous coordination model, which exhibits a separation of concern between computation and communication activities, and helps resolve some of the challenges brought about by the dynamic and large scale nature of CPSCN systems.