This paper aims at promoting the application of self-organising techniques to software service coordination in the context of highly dynamic and mobile environments, such as those of pervasive computing. We describe a framework where a network of shared tuple spaces handles services provided by situated agents, enabling their composition and competition in a fully distributed, self-organised way. This is achieved by a set of coordination laws structured as chemical-resembling reactions, designed so as to enact feedback loops that regulate and balance the “activity level” of (atomic or composite) services.