Mechanisms for environments in multi-agent systems: Survey and opportunities <s> Notification of contextual events <s> Multi-agent systems can benefit from the possibility of broadcasting messages to a wide audience. The audience may include overhearing agents which, unknown to senders, observe conversations and, among other things, pro-actively send suggestions. Current mainstream agent communication languages however lack adequate support for broadcasting. This paper defines the requirements for a form of broadcast that we call channeled multicast, whose distinguishing features include the ability to distinguish streams of messages by their theme, and to address agents by their characteristics. We present an implementation based on multicast IP, called LoudVoice. We show how channeled multicast could be used in alternative to matchmaking, and present in some detail a broadcast-based version of the English Auction Interaction Protocol. Finally, we discuss how we use the ability to overhear conversations in order to build innovative applications and we present a case study which is a testbed for various types of agents and multi-agent systems. <s> BIB001 </s> Mechanisms for environments in multi-agent systems: Survey and opportunities <s> Notification of contextual events <s> This paper presents a new model of agency, called the KGP (Knowledge, Goals and Plan) model. This draws from the classic BDI model and proposes a hierarchical agent architecture with a highly modular structure that synthesises various reasoning and sensing capabilities of the agent in an open and dynamic environment. The novel features of the model include: its innovative use of Computational Logic (CL) in a way that facilitates both the formal analysis of the model and its computational realisability directly from the high-level specification of the agents (a first prototype for the development of KGP agents exists, based upon a correct computational counterpart of the model), the modular separation of concerns and flexibility afforded by the model in designing heterogeneous agents and in developing independently the various components of an agent, and the declarative agent control provided through a context-sensitive cycle CL theory component that regulates the agent's operational behaviour, according to the current circumstances of operation, thus breaking away from the conventional one-size-fits-all control of operation. <s> BIB002
Name: Notification of contextual events. Motivations: Need for the production and delivery of event notifications to create dynamic agent contexts. Constituent atoms: Event dispatcher repositories. Creation and maintenance: Protocols to let new agents subscribe to event sources and be notified upon event happening. Usage: Agents trigger reaction on the basis of the events received. Examples: Interaction filters  , LoudVoice BIB001 , Tag interactions  The notification of contextual events is a mechanism that provides agents spontaneously with information about surrounding events in the environment. Events (from other agents or resources) trigger information flows generated by the environment to inform agents about the evolution of their local context. The constituent atoms of the mechanisms are the event dispatcher repository. Creation and maintenance are supported by algorithms to subscribe to specific event sources, to generate the events, and to deliver the events to suitable recipients. Finally, agents use the mechanism depending on application needs, e.g. to revise their knowledge about the surrounding world BIB002 . The 'Environment to Support Active Communications' (ESAC) is an example of context notification in MAS  . The environment has the architecture of an extensible mail server. Extensions are 'filters' placed by agents in the environment with a configuration rule to process messages that flow in the system. Rules allow agents to define the types of messages they want to receive, in addition to the ones addressed to them (filters model an instance of publish-subscribe patterns). ESAC was applied to a bus fleet management system where, for example, bus agents configure filters to receive all messages about traffic congestion between their current positions and the terminal stop. Complex event notifications can be defined with a language that specifies the filters placed in the environment.