The paper presents the TuCSoN coordination model for Internet applications based on network-aware (possibly mobile) agents. The model is based on the notion of tuple centre, an enhanced tuple space whose behaviour can be extended according to the application needs. Every node of a TuCSoN environment provides its local communication space, made up of a multiplicity of independently-programmable tuple centres. This makes it possible to embed global system properties into the space of components' interaction, thus enabling flexible cooperation over space and time between agents, and permitting to easily face many issues critical to Internet applications, such as heterogeneity and dynamicity of the execution environments.