Data processing of today (like communication networks, multiagent systems, swarm intelligence, ubiquitous, wearable and mobile computing) is often distributed and comprises various components that run partially independent of each other, but may access and update the same information structures, communicate with each other and interact in various ways. These components may cooperate to reach a common goal or may compete with each other to achieve their individual aims. Typical examples of this kind are logistic processes and systems like transport and production networks where many actors from different companies come together and cooperate to a certain degree. But they are usually still competitors who are not willing to transfer their control to others or to a central entity. This presentation introduces the notion of a community of autonomous units as a rule-based and graph-transformational device to model processes that run interactively but independently of each other in a common environment. The emphasis of the approach is laid on the study of the formal semantics of a community as a whole and of each of its member units separately.