CommonKADS communication model

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


Relation to other models

organiz a tion modeltas k modelagent model

knowledge-‐intens ive

ta s k

communicationmodel

knowledgemodel

des ignmodel

requirementss pec ifica tion

for intera ction functions

requirementss pec ifica tion

for rea s oning functions

tas k s elec ted in feas ib ility s tudyand further detailed in Tas k and Agent Models


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.


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 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: overview

Task Model

Tas k

I/O info objec ts.....

Agent Model

Agent

capabilitie s.....

T rans ac tion

identifie r/nameI/O info objec tsa g ents involved

communica tion plancons tra ints

info exchange s pec

InformationE xchang e

S pec ific ation

C ommunic ationP lan

K nowledge Model

Tas k s truc ture

trans fer functions.....

involved-‐in involved-‐in

involved-‐in

part-‐of part-‐of

dia logue dia g ramtrans a ction control

communica tion typemes s age contentmes s age controlinfo form/medium

Focuses on modeling the dialogue between agents"""Structured, semi-formal approach"


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


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


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


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 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 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


Dialogue Diagram: general structure

Task A2

Task A3

Task A4

Task B 2

Task A5

Ag ent A(e.g . us er)

Task B 3

Ag ent B(e.g . s ys tem)

Task B 4

Task A1

Dialog ue

Transac tionTr. 1

Transac tionTr. 2

Transac tionTr. 3

Task B 1

Transac tionTr. 4

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


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


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"

Announce E xpressP references

B id

Assess

Award

S chedule

Implement

Monitor Monitor

COMMUNICATE

Utility C us tomer


CP for the housing application

applicationas s es sment

waiting for cas e data

application received/order as s es sment

data needed/as k

data received / reply

as s es sment finis hed/report dec is ion


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)


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)


Homebots Dialogue Control

R eduction need?

Auc tionRunning

Announce & Kick-‐off

As s es s

Interes ted? N Interes ted? YOpt out E xpres s P re fs .

Opted Out P referencesC alc ulated

B ids rece ived?

P ower need?B id & S ubmit

B idS ubmitted

Converg ence? N C onverg ence? YAwa rd & P res ent

Next R ound

Auc tion C ompleted/Awards D is tributed

Alloc ationC omputed


Communication Model: Middle Level

Specification of individual transactions, structured in a number of components:"""Simple worksheet techniques are helpful here"

TR ANS -‐AC T ION

identifier& name

agentsinvolved

communic ationplan

informationobjec ts

information exchangespec ific ation

constraints


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


Transaction “Housing” (1)

Transaction name Order application assessment

Information object a residence application

Agents involved data entry + knowledge system(+ assigner)

Comm. Plan active when application arrives.

Constraints Prototyping: interact with user

Informtation exchange ransaction is of the “order”type


Transaction “Housing” (2)

Transaction name Obtain application data

Information object Attribute-value pairs of an aapplicant and residence

Agents involved database + knowledge system

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

Constraints Ensure mapping of datarequest onto DB data format

Informtation exchange transaction is of the ask-replytype.


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!"


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: 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 types

Task delegation Task adoption Informationexchange

Request Propose Ask

Require Offer Reply

Order Agree Report

Reject-td Reject-ta Inform


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.


Typed Message Patterns

INFORM

AS K

C ommunic ation type patterns

1)

2)

RE P LY

3)

ORDE R

RE PORT

AGRE E

RE PORT

4)

AGRE E

5)

RE QUIRE

RE J E C T-‐ta

ORDE R

6)

OF F E R

RE J E C T-‐td

P ROPOS E

7)

RE QUE S T

OF F E R RE J E C T-‐ta

RE QUE S T

8)

P ROPOS E

RE QUIRE RE J E C T-‐td

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

Communication Patterns "


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


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


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


Control over messages

■  Refinement of control in communication plan ■  Notations: the same

➤  State diagram ➤  Pseudo code


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


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


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 ■  …..


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 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

CommonKADS communication model

Technology

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