Communication Model

The Communication Plan

Specifying agent-agent transactions

Transaction patterns

Communication Model 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

Communication Model 3

Relation to other models

organization modeltask model

agent model

knowledge-intensive

task

communicationmodel

knowledgemodel

designmodel

requirementsspecification

for interaction functions

requirementsspecification

for reasoning functions

task selected in feasibility studyand further detailed in

Task and Agent Models

Communication Model 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.

Communication Model 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

Communication Model 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?

Communication Model 7

Communication model:overview

Task Model

Task

I/O info objects.....

Agent Model

Agent

capabilities.....

Transaction

identifier/nameI/O info objectsagents involved

communication planconstraints

info exchange spec

InformationExchange

Specification

CommunicationPlan

Knowledge Model

Task structure

transfer functions.....

involved-in involved-in

involved-in

part-of part-of

dialogue diagramtransaction control

communication typemessage contentmessage controlinfo form/medium

Focuses on modeling the dialogue between agents

Structured, semi-formal approach

Communication Model 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

Communication Model 9

Sample application

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

utilityutility customercustomer utilityutility customercustomerkWh

&

kWh

info

Communication Model 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

Communication Model 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

Communication Model 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

Communication Model 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

Communication Model 14

Dialogue Diagram: general structure

Task A2

Task A3

Task A4

Task B2

Task A5

Agent A(e.g. user)

Task B3

Agent B(e.g. system)

Task B4

Task A1

Dialogue

TransactionTr. 1

TransactionTr. 2

TransactionTr. 3

Task B1

TransactionTr. 4

Note: agent's (leaf) tasks are key entry to dialogue diagram construction

Communication Model 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

Communication Model 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

AnnounceExpress

Preferences

Bid

Assess

Award

Schedule

Implement

Monitor Monitor

COMMUNICATE

Utility Customer

Communication Model 17

CP for the housing application

applicationassessment

waiting for case data

application received/order assessment

data needed/ask

data received / reply

assessment finished/report decision

Communication Model 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)

Communication Model 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)

Communication Model 20

Homebots Dialogue Control

Reduction need?

AuctionRunning

Announce & Kick-off

Assess

Interested? N Interested? YOpt out Express Prefs.

Opted OutPreferencesCalculated

Bids received?

Power need?Bid & Submit

BidSubmitted

Convergence? NConvergence? Y

Award & PresentNext Round

Auction Completed/Awards Distributed

AllocationComputed

Communication Model 21

Communication Model:Middle Level

Specification of individual transactions, structured in a number of components:

Simple worksheet techniques are helpful here

TRANS-ACTION

identifier& name

agentsinvolved

communicationplan

informationobjects

information exchangespecification

constraints

Communication Model 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

Communication Model 23

Transaction “Housing” (1)

Transaction name Order application assessment

I nformation object a residence application

Agents involved data entry + knowledge system(+ assigner)

Comm. Plan active when application arrives.

Constraints Prototyping: interact with user

I nformtation exchange ransaction is of the “order”type

Communication Model 24

Transaction “Housing” (2)

Transaction name Obtain application data

I nformation object Attribute-value pairs of an aapplicant and residence

Agents involved database + knowledge system

Comm. Plan transitions connected to the“waiting f or data” state

Constraints Ensure mapping of datarequest onto DB data f ormat

I nformtation exchange transaction is of the ask-replytype.

Communication Model 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!"

Communication Model 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?

Communication Model 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)

Communication Model 28

Communication types

Task delegation Task adoption Informationexchange

Request Propose Ask

Require Offer Reply

Order Agree Report

Reject-td Reject-ta Inform

Communication Model 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.

Communication Model 30

Typed Message Patterns

INFORM

ASK

Communication type patterns

1)

2)

REPLY

3)

ORDER

REPORT

AGREE

REPORT

4)

AGREE

5)

REQUIRE

REJ ECT-ta

ORDER

6)

OFFER

REJ ECT-td

PROPOSE

7)

REQUEST

OFFER REJ ECT-ta

REQUEST

8)

PROPOSE

REQUIRE REJ ECT-td

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

Communication Patterns

Communication Model 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

Communication Model 32

Transaction “submit-the-bid”:message specifications

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

Communication Model 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

Communication Model 34

Control over messages

Refinement of control in communication plan Notations: the same

State diagram Pseudo code

Communication Model 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

Communication Model 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

Communication Model 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 …..

Communication Model 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

Communication 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