There is little empirical evidence of sustainable open innovation collaboration between SMEs and educational institutions under a Living Lab as an ecosystem. Consequently, there is scarce knowledge on how to engage SMEs, universities, and end users into a value creation based on sustainable open innovation collaboration. A social process model is used to describe the relationships between key actors within the Living Lab. The resulting model depicts in a concise way how the relationships have evolved over time. In this model, major encounters between the actors are those which have at least the potential to change the relationship state between the parties. The relatively stable passages between consecutive encounters are labelled episodes. By perceiving systems development in the open innovation ecosystem as a series of encounters and episodes in IT business development, it is possible to identify the critical milestones of development work and to display the dynamics of a use-case development trajectory.