The objective of this paper is to discuss how to sustain the growth of Web services through the use of communities. A community aims at gathering Web services with the same functionality independently of their origins, locations, and functioning. To make Web services more responsive to the environment in which they run and to be more flexible when managing communities, Web services are associated with software agents enhanced with argumentation capacities. This type of agents persuade and

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... ate with other peers for the sake of letting their respective Web services reach their goals in an efficient way. Associating Web services with this type of agents allows them to select good communities and allow the communities to host the good Web services and to select the best ones for composite scenarios. Furthermore, this provides satisfactory solutions for three open problems: starvation (Web services refuse all the possibilities of joining communities), competition-free (Web services accept joining any community without being selective), and unfairness (always the same Web services members of a community are selected out of many others to participate in composite scenarios). In addition, the paper presents a formal and computational persuasive and negotiation protocol to manage the attraction and retainment of Web services in the communities and their identification for composite services.