Communication Model

1. Communication Model The Communication Plan Specifying agent-agent transactions Transaction patterns

2. 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

3. Relation to other models

4. 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.

5. Information systems:communication 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

6. 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?

7. Communication model:overview Focuses on modeling the dialogue between agents Structured, semi-formal approach

8. Communication Model:overview • 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

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

10. 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

11. 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

12. 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

13. 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

14. Dialogue Diagram: general structure Note: agent's (leaf) tasks are key entry to dialogue diagram construction

15. New Customer Services:ICT 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

16. 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

17. CP for the housing application

18. 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)

19. 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)

20. Homebots Dialogue Control

21. Communication Model:Middle Level Specification of individual transactions, structured in a number of components: Simple worksheet techniques are helpful here

22. Illustration Middle Level:Homebots 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

23. Transaction “Housing” (1)

24. Transaction “Housing” (2)

25. 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!"

26. 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?

27. Communication Model:Detail 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)

28. Communication types

29. 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.

30. Typed Message Patterns Not only typing of single messages possible. Also, natural chains of message types can be formed (cf. COSY): Communication Patterns

31. 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

32. Bid-message type:PROPOSE 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 Transaction “submit-the-bid”:message specifications

33. 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

34. Control over messages • Refinement of control in communication plan • Notations: the same • State diagram • Pseudo code

35. Transaction: submit-the-bid REPEAT WHILE <market convergence condition not satisfied> IF <interest in load management> THEN PROCESS(bid-task); SEND(BID-MESSAGE) ELSE SEND(OPT-OUT-MESSAGE) END-IF IF <bids received> THEN PROCESS(assess-task) ELSE PROCESS(decision subprocedure [e.g. WAIT...]) END-IF SEND(AUCTION-DATA-MESSAGE) & SEND(NEXT-ROUND-MESSAGE) END-REPEAT

36. 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

37. 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 • …..

38. 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

39. 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