Communication Model

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Communication Model

• The Communication Plan
• Specifying agent-agent transactions
• Transaction patterns

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Role of Communication Model

• specifies knowledge/information transfer
  procedures
• top-level control over task execution
• multiple knowledge-intensive tasks
• additional communication tasks
• explanation facilities
• example basic system-user interaction

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Relation to other models
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Input for communication modeling

• Task Model
• list of leaf tasks carried out by the considered
  agents
• Knowledge Model
• transfer functions
• Agent Model
• description of relevant agents capabilities,
  responsibilities constraints.

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Information systemscommunication

• More and more, IS are becoming information
  communication systems
• distributed applications (telematics)
• virtual organizations
• CSCW
• intelligent multi-agent systems
• workflow management
• concurrent engineering
• business chain management and integration

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Communication between actors

• Information modeling must cover
• Organizational/Business analysis
• Task/Workplace analysis
• Actor/Agent analysis (both human and system)
• Usually, several actors cooperate in a business
  process or task, so
• Communication model intends to capture agent
  interactions within a joint task
• Communication Model conceptual specification
  of
• what kind of information objects are exchanged
  between agents in cooperating in and carrying out
  a task, and how?

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Communication modeloverview
Focuses on modeling the dialogue between
agents Structured, semi-formal approach
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Communication Modeloverview

• Layered approach to Communication Modeling
• Three levels
• 1. The overall communication plan, which governs
  the full dialogue between two agents
• 2. The individual transactions that link two
  (leaf) tasks carried out by two different agents
• 3. The information exchange specification that
  details the internal message structure of a
  transaction
• Start to construct the global overview, and fill
  in the details later

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Sample application

• Energy market
• dynamic pricing of energy
• enables companies to do load management
• HOMEBOTS intelligent electrical agents
• requires two-way communication system

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Transaction

• key component of Communication Model
• describes what information objects are exchanged
• indicates agents and tasks involved
• go-between of two tasks carried out by different
  agents
• building blocks for the full dialogue between two
  agents
• transactions have an internal structure
• example obtain

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Other CM concepts

• Communication plan
• governs the full dialogue between the agents
• organization of transactions
• Information exchange specification
• details transaction structure
• consists of messages
• only necessary for complex communications

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Communication Plan

• easiest to begin with the overall communication
  plan
• describes full top-level dialogue
• typical transactions
• data input
• asking or answering questions
• presentation of reasoning results
• explanation of results

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Communication plan activities

• for each agent list all tasks
• for each task identify set of associated
  agent-agent transactions
• results combined in dialogue diagram"
• DD depicts transactions between two agents
• draw a DD for each combination of two agents that
  exchange a reasonable amount of information
• specify control over the transactions

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Dialogue Diagram general structure
Note agent's (leaf) tasks are key entry to
dialogue diagram construction
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New Customer ServicesICT Technology

• Through networked microprocessors, devices can
  'talk to', 'negotiate', 'make decisions', and
  'cooperate' with one another.
• Smart equipment agents we call homebots (inspired
  by Star Trek and Asimow's Robot Stories)
• We use this,e.g., for distributed power load
  management (Further info see separate case)
• Benefits
• handles much larger scale
• higher degree of automation decentralized
  flexible approach
• proactive for the customer

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DD for energy market
Task and transaction links in power auction are
graphically sketched in the dialogue
diagram Gives overview of the system's
communication plan
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CP for the housing application
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Transactions in the Homebots System

• Transaction list
• 1. Kick-off the auction sends a trigger signal
  to the customer agents to commence a load
  management action
• 2. Submit the bids transmits the bids from the
  customer agents to the auctioneer for further
  processing
• 3. Present the awarded power allocation informs
  the customer agents about the results of the
  auction
• 4. Present the associated real-time schedule
  provides the customer agents with the calculated
  schedule that implements the awarded allocation
• 5. Receive the resulting real-time implementation
  data transmits the actual metering data (Needed
  for billing and for assessing the need for
  further load management actions)

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Transaction control notations

• state diagrams
• pseudo-code with special control primitives
• SEND, RECEIVE
• CARRY-OUT (SEND/RECEIVE combination)
• WAIT-until/while
• PROCESS (task)
• (sequence)
• REPEAT-until/while, IF THEN ELSE
• (AND), (choice), V (OR)

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Homebots Dialogue Control
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Communication ModelMiddle Level
Specification of individual transactions,
structured in a number of components Simple
worksheet techniques are helpful here
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Illustration Middle LevelHomebots System (II)

• Submit-the-bid transaction description (Worksheet
  CM-1)
• Identifier/Name Transaction 2 Submit-the-bid
• Information objects linking Bid and Assess
  tasks (1) bid (2) going price or going
  allocation (depending on domain theory)
• Agents involved (1) customer agents (2)
  auctioneer/utility agent
• Communication plan Homebots (base version)
• Constraints (1) decision procedure for bidding
  completeness (2) market convergence
  postcondition
• Information Exchange Spec See Worksheet CM-2
• Note this transaction contains more than one
  message, and so is composite

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Transaction Housing (1)
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Transaction Housing (2)
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Composite Transactions

• "I'm getting cold, so could you please shut the
  door?''
• First part is just information notification
  message
• Second part is request for action by the other
  agent task delegation message
• So, within one transaction two messages
  differring in both content and intent
• Transactions not only transmit content, but also
  an intended relationship between two agents. Both
  these aspects must be explicitly specified.
• Compare "Hey, idiot, shut the door, I'm getting
  cold!"

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Speech Acts

• Agent communication languages often inspired by
  so-called speech act theory
• Makes distinctions between
• Content ('locutionary nature') of a speech act or
  message -- what is actually being said --
• Intended effect ('illocutionary force') on the
  other agent
• Actual effect ('perlocutionary force') on the
  other agent
• N.B. nice communication modeling exercises
• "It's the economy, stupid!''
• Edward Albee's Who's Afraid of Virginia Woolf?

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Communication ModelDetail Level

• Detailed message specification
• 1. Content (locution) by means of a
  propositional statement
• 2. Intention (illocution) by means of typing a
  message
• Predefined types
• Task Delegation Request Require Order
  Reject-td
• Task Adoption Propose Offer Agree Reject-ta
• Pure Information Exchange Ask Reply Report
  Inform
• Note Intention purpose x commitment
• Cf. performatives in KQML (DARPA Knowledge
  Sharing Effort) and esp. COSY (Daimler-Benz)

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Communication types
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Semantics of Communication Types

• Request/Propose potential for cooperation, but
  agent wishes to negotiate on the terms. Loosely
  I have an interest, but not yet a commitment'.
• Require/Offer agent already has made a
  pre-commitment, and intends to prompt the
  receiving agent for its commitment. This type
  thus denotes a conditional commitment.
• Order/Agree agent has made a commitment, and
  thus will act accordingly.
• Reject-td/ta denote that the agent does not want
  to commit or cooperate.
• Ask/Reply have as intent a query for information
  from another agent, and delivery of information
  in return.
• Report types a message sent after an agent has
  acted towards a (previously) agreed task goal,
  with the intention to let the other agent know
  the status of achievement (e.g. success, failure,
  outcome of the action).
• Inform refers to a message type that just
  delivers information objects to another agent.
  Indicates an independent informative action no
  previous request or agreement involved.

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Typed Message Patterns
Not only typing of single messages possible.
Also, natural chains of message types can be
formed (cf. COSY) Communication Patterns
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Worksheet CM-2 Information Exchange Specification

• Only needed for complex communication patterns
• energy market
• Worksheet structure
• Transaction Identifier/Name
• Agents involved sender, receiver
• Information items
• Message specification
• Message control

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Transaction submit-the-bidmessage
specifications

• Bid-message
• typePROPOSE
• content bid
• from customer agent
• to auctioneer
• Opt-out-message
• type REJECT-TA
• content no part
• from customer agent
• to auctioneer

• Auction-data-message
• type INFORM
• content market data
• from auctioneer
• to customer agent
• Next-round-message
• type REQUEST
• content trigger next round
• from auctioneer
• to customer agent

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Information items

• role
• core object
• support item
• explanation texts of domain material
• rock photographs, mineral photographs
• reasoning traces
• WHY/HOW explanations
• syntactic form data string, diagram, ...
• medium pop-up window, command-line interface,
  human intervention,
• cf. Design issues

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Control over messages

• Refinement of control in communication plan
• Notations the same
• State diagram
• Pseudo code

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Transaction submit-the-bid

• REPEAT WHILE ltmarket convergence condition not
  satisfiedgt
• IF ltinterest in load managementgt
• THEN PROCESS(bid-task) SEND(BID-MESSAGE)
• ELSE SEND(OPT-OUT-MESSAGE)
• END-IF
• IF ltbids receivedgt
• THEN PROCESS(assess-task)
• ELSE PROCESS(decision subprocedure e.g.
  WAIT...)
• END-IF
• SEND(AUCTION-DATA-MESSAGE)
• SEND(NEXT-ROUND-MESSAGE)
• END-REPEAT

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Validation techniques

• Communication-plan walk-through
• adequacy transaction structure
• completeness list of information items
• need for help or explanation
• Wizard-of-Oz technique
• experimental technique to validate interaction
• mock-up software

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Nielsen's guidelines for usability engineering

• Present a simple and natural dialogue
• Speak the user's language
• Minimize the user's memory load
• Maintain consistency in terminology
• Give feedback about what is going on
• Show clearly marked exits from unwanted states
• Offer shortcuts for the experienced user
• ..

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Guidelines for balancing the communication model

• Key inputs
• leaf tasks TM
• transfer function KM
• Take agent capabilities into account (see AM)
• syntactic form of media is area of both CM and DM
• guideline in CM if conceptual reason
• Decide here about support information
• not in design model

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Communication model activities

• Identify core information objects to be exchanged
  between agents
• Identify associated transactions
• Draw important dialogue diagrams
• Combine this to a full communication plan
• Specify the individual transactions
• worksheets CM-1 and CM-2
• Validate and balance the model