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Ch. 9 of the CommonKADS textbook
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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
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
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
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 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 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"
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"
Announce E xpressP references
B id
Assess
Award
S chedule
Implement
Monitor Monitor
COMMUNICATE
Utility C us tomer
Communication Model 17
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
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
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 21
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
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
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
Communication Model 24
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.
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
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 "
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
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