The paper discusses basic abstractions underlying the development of complex software systems in multiagent systems terminology, and also presents a new methodology to guide developers in the design of software systems built according to the multiagent systems paradigm. In particular, this paper presents a methodology called "Gaia" as a means to develop software systems according to a new so-called "organizational metaphor," which seems suited to a variety of modern complex software systems.

Modern software systems are becoming increasingly complex. Their components are widely distributed and can belong to different stakeholders. They can vary in number during the execution of the system, interact with each other according to very dynamic patterns, and are situated in operational environments exhibiting unpredictable dynamics. This challenges the traditional approaches to software development, and calls for brand new paradigms and methodologies. This paper proposes the use of multiagent systems as the new paradigm, and the "Gaia" methodology which, when followed, reasonably answers the needs of modern software development.

This paper is the result of an international collaboration. It brings together the diverse expertise of three research groups of excellence: the "Agents and Pervasive Computing Group" at the University of Modena and Reggio Emilia, the "Agents and Multimedia Group" at the University of Southampton, and the "Agent ART Group" at the University of Liverpool. As so often happens, the sharing of different—sometimes even contrasting—opinions and perspectives promoted the reaching of a novel understanding which led to the new synthesis contained in this paper.