The paper describes the design and the Java implementation of a coordination architecture for mobile agents, based on an object-oriented Linda-like tuple space model, compliant with the Sun's JavaSpaces specifications. Moreover, unlike Linda and JavaSpaces, the proposed architecture integrates a reactive model: the behaviour of the tuple spaces can be programmed by installing reactions which are triggered by the accesses of mobile agents to the tuple spaces. Reactions can increase the coordination flexibility and ease agent programming, as shown via an application example in the network management area.