The aim of this phase consists in modeling the lifecycle of each agent, looking at the roles it can play, the collaboration it needs, and the communications in which it participates.
In the R.D. diagram we introduce all the rules of the society (organizational rules, [7]), laws of the society and the domain in which the agent operates (e.g. trade laws) and the behavioral laws considered by Newell in his “social level” [27]; these rules could be expressed in plain text or OCL in order to have a more precise, formal description.
The Role Description diagram (Figure 17) is a class diagram where roles are classes grouped in packages representing agents. Roles can be connected by relationships representing changes of role, by dependencies for a service or the availability of a resource and by communications. Each role is obtained composing several tasks for this reason we specify the tasks involved in the role using the operation compartment of each class.
We consider the following kinds of dependency:
We can introduce external actors (representing external or not agent-based applications) in order to represent the agents interactions with other systems. In this case interactions can occur using communications (this is the case of agent-based external systems) or several different ways (remote call procedure, web services invocation …).
In the next figure we can see a portion of RD diagram representing the roles, agents and communications involved in the scenario already presented in sub-section Domain Ontology Description; the Agent_Society agent (User_Interaction role) requires the COD_Compilation service from the COD agent (Automatic_Compilation role) with the Start_Compostition communication. In this last agent the Compose_Diagram task receives the communication as prescribed by the T.Sp. diagram; then the agent asks for the list of interactions among agents to the Agent_Society agent. Once the Automatic_Compilation role of the COD agent has completed its duty, then a change of role occurs and the agent starts to play the User_Interaction role. During this phase, the agent waits for user inputs (clicks on communications reported in the diagram) and then shows the form that the designer uses to introduce some communication parameters.
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