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Compact and Efficient Agent MessagingKai Jander and Winfried LamersdorfDistributed Systems and Information SystemsComputer Science Department, University of Hamburg{jander | lamersd}@informatik.uni-hamburg.deAbstract. Messages are considered to be a primary means of communicationbetween agents in multi-agent systems. Since multi-agent systemsare used for a wide variety of applications, this also includes applicationslike simulation and calculation of computer generated graphics whichneed to employ a large number of messages or very large messages toexchange data. In addition, other applications target hardware whichis resource constrained by either bandwidth or processing capacity. Asa result, these applications have different requirements regarding theirmessages. This paper proposes a number of useful properties for agentmessages and evaluates them with regard to various types of applications.Based on this evaluation a message format for Jadex called Jadex Binaryis proposed, which emphasizes properties that are not traditionally thefocus of agent message formats and compared them to some well-knownformats based on those properties.1 IntroductionMulti-agent systems enable the development of scalable and highly dynamicapplications, facilitating their deployment on infrastructure such as structurallyor spatially distributed systems, and the integration of mobile devices in suchsystems. An important means for agents to coordinate within an multi-agentapplication are messages passed between them. This mechanism is one of theenabling factors for autonomous behavior of agents, which enables them to beprotected from direct influence by the rest of the system and establish a measureof robustness.Nevertheless, certain classes of applications deployed on such systems havespecial requirements which appear to be in conflict with the focus of traditionalagent message formats. Examples of this type of applications include real-timeaudio and video communication, distributed simulation and real-time distributedcomputer generated image (CGI) animation.Traditionally, these requirements have not been the focus of agent messaging,which tends to target other useful properties that can also be important in multiagentapplications. As a result, it would broaden the application scope of agentsystems if they specifically supported the requirements of such applications byproviding an alternative message format.101
In the following section we will attempt to identify typical requirements foragent messages and distill some that are especially important to the aforementionedclasses of applications. We will then introduce some typical message formatsused in agent systems and attempt to identify which application requirementsthey attempt to fulfill. Finally, we will present a compact message formatthat caters to the special class of application with real-time and bandwidthrestrictedsets of requirements and compare it to traditional agent message formats,demonstrating key advantages for this special set of applications.2 Features of Agent Message FormatsSince multi-agent applications cover a large spectrum of potential applications,there is an equally large number of features associated with agent messageswhich are potentially useful for different classes of applications. In addition todifferent application classes, different points in the development cycle may alsoemphasize the importance of certain features over others. While there is a largenumber of arguably useful features, we propose the following six features whichare commonly mentioned and requested for multi-agent applications:– Human Readability allows humans to read messages with standard tools liketext viewers without the help of decoders or other special tools.– Standard Conformance requires messages to conform to a published messageformat standard or language standard, allowing interaction between systemsconforming to those standards.– A Well-formed Structure defines a valid form for messages, allowing thesystem to distinguish between valid and invalid messages.– Editability goes beyond human readability by allowing users to edit andrestructure messages using standard tools such as text editors.– Performance describes the computational requirements to encode and decodemessages.– Compactness evaluates the size of encoded messages.In order to evaluate these features, we propose an example set of four commonclasses of applications. While there are many more potential applications,these applications are very common and would benefit from the use of agenttechnology. The first type of applications are real-time applications, where latencyis a primary concern. Examples of this type of application can be foundin any real-time communication application such as voice or video conferencesystems. High latency is generally unacceptable in such applications and mayseverely inhibit their functionality.The second type of applications are cross-platform applications. For example,Agentcities[1] allows the use of multiple agent platforms and multiple types ofagents, requiring precise definitions and standards among them. Correct interpretationof messages from other agents or platforms is key for such applications.Another common type of applications involve enterprise backend applications.These applications often run on application servers on high-performance102
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Proceedings of the Tenth Internatio
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OrganisationOrganising CommitteeMeh
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Table of ContentseJason: an impleme
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in Sect. 3 the translation of the J
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init_count(0).max_count(2000).(a)(b
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For instance, a failure in the ERES
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{plan, fun start_count_trigger/1,fu
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single parameter, an Erlang record
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1. Belief annotations. Even though
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decisions taken during the design a
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Conceptual Integration of Agents wi
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Fig. 2. Active component structurep
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the service provider component. As
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Fig. 4. Web Service Invocationretri
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01: public interface IBankingServic
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tate them in the same way as in the
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01: public interface IChartService
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implementations being available for
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deliberative behavior in BDI archit
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layer modules (i.e. nodes) can be d
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different methods to choose the cur
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also a single scheduler module, imp
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andom choice (OR), conditional choi
Page 52 and 53: - Dealing with conflicts based on p
Page 54 and 55: 5. Brooks, R. A. (1991) Intelligenc
Page 56 and 57: An Agent-Based Cognitive Robot Arch
Page 58 and 59: It has been argued that building ro
Page 60 and 61: EnvironmentHardwareLocal SoftwareC+
Page 62 and 63: a cognitive layer can connect as a
Page 64 and 65: can reliably be differentiated and
Page 66 and 67: 4 ExperimentTo evaluate the feasibi
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Page 70 and 71: A Programming Framework for Multi-A
Page 72 and 73: exchange and storage of tuples (key
Page 74 and 75: Although some success [13] [14] hav
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Page 80 and 81: A in the example) can evaluate all
Page 83 and 84: 1. robot-1 issues a Localization(ro
Page 85 and 86: ACKNOWLEDGMENTThis work has been su
Page 87 and 88: The code was analysed both objectiv
Page 89 and 90: a conversation is following. Additi
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Page 93 and 94: Table 1. Core Agent ProtocolsAgent
Page 95 and 96: statistically significant using an
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Page 99 and 100: principal reasons. Firstly, it is a
Page 101: 2. Muldoon, C., O’Hare, G.M.P., C
Page 105 and 106: DevelopmentProductionHuman Readabil
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Page 115 and 116: Java serialization and Jadex Binary
Page 117 and 118: 10. P. Hoffman and F. Yergeau, “U
Page 119 and 120: Caching the results of previous que
Page 121 and 122: querying an agent’s beliefs and g
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Page 127 and 128: Size N K n p c qry U c upd Update c
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Page 131 and 132: 6 ConclusionWe presented an abstrac
Page 133 and 134: Typing Multi-Agent Programs in simp
Page 135 and 136: 1 // agent ag02 iterations (" zero
Page 137 and 138: 3.1 simpAL OverviewThe main inspira
Page 139 and 140: 3.2 Typing Agents with Tasks and Ro
Page 141 and 142: Defining Agent Scripts in simpAL (F
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Page 149 and 150: Learning to Improve Agent Behaviour
Page 151 and 152: 2.1 Agent Programming LanguagesAgen
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choosing actions is to find a good
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1 init module {2 knowledge{3 block(
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of a module. For example, to change
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if bel(on(X,Y), clear(X)), a-goal(c
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mance. Figure 2d shows the same A f
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the current percepts of the agent.
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Author IndexAbdel-Naby, S., 69Alelc
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