Ch. 9 of the CommonKADS textbook

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

2. 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

3. Communication Model 3
Relation to other models
organiz ation
model
tas k
model
agent
model
knowledge-­‐
intensive
task
communication
model
knowledge
model
des ign
model
requirements
specification
for
interaction
functions
requirements
specification
for
reasoning
functions
task
selected
in
feasibility
study
and
further
detailed
in
Task
and
Agent
Models

4. 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.

5. 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

6. 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?

7. Communication Model 7
Communication model:
overview
Task
Model
Tas k
I/O
info
objects
.....
Agent
Model
Ag ent
capabilities
.....
Trans action
identifier/name
I/O
info
objects
agents
involved
communication
plan
constraints
info
exchange
spec
Information
E xchang e
S pecification
C ommunication
P lan
K nowledge
Model
Tas k
s tructure
transfer
functions
.....
involved-­‐in involved-­‐in
involved-­‐in
part-­‐of part-­‐of
dialogue
diagram
transaction
control
communication
type
message
content
message
control
info
form/medium
Focuses on
modeling the
dialogue between
agents"
"
"
Structured, semi-
formal approach"

8. 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

9. 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 customercustomer
kWh
&
kWh
info

10. 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

11. 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

12. 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

13. 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

14. Communication Model 14
Dialogue Diagram: general
structure
Task
A2
Task
A3
Task
A4
Task
B 2
Task
A5
A g ent
A
(e.g .
us er)
Task
B 3
A g ent
B
(e.g .
s ys tem )
Task
B 4
Task
A1
D ialog ue
Transac tion
Tr.
1
Transac tion
Tr.
2
Transac tion
Tr.
3
Task
B 1
Transac tion
Tr.
4
Note: agent's
(leaf) tasks
are key entry
to dialogue
diagram
construction"

15. 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

16. 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 xpress
P references
B id
Assess
Award
S chedule
Implement
Monitor Monitor
C
O
M
M
U
N
I
C
A
T
E
Utility C us tomer

17. Communication Model 17
CP for the housing application
application
assessment
waiting
for
case
data
application
received/
order
assessment
data
needed/ask
data
received
/
reply
assessment
finished/
report
decision

18. 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)

19. 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)

20. Communication Model 20
Homebots Dialogue Control
R eduction
need?
Auction
Running
Announce
&
Kick-­‐off
Assess
Interested?
N Interested?
Y
Opt
out E xpress
Prefs.
Opted
Out
Preferences
C alculated
Bids
received?
Power
need?
Bid
&
S ubmit
Bid
S ubmitted
Convergence?
N
Convergence?
Y
Award
&
Present
Next
R ound
Auction
C ompleted/
Awards
Distributed
Allocation
C omputed

21. Communication Model 21
Communication Model:
Middle Level
Specification of individual
transactions, structured in
a number of components:"
"
"
Simple worksheet
techniques are helpful
here"
T R ANS -­‐
AC T ION
identifier
&
name
agents
involved
communication
plan
information
objects
information
exchange
specification
constraints

22. 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

23. 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

24. Communication Model 24
Transaction “Housing” (2)
Transaction name Obtain application data
Information object Attribute-value pairs of an a
applicant and residence
Agents involved database + knowledge system
Comm. Plan transitions connected to the
“waiting for data” state
Constraints Ensure mapping of data
request onto DB data format
Informtation exchange transaction is of the ask-reply
type.

25. 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!"

26. 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?

27. 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)

28. Communication Model 28
Communication types
Task delegation Task adoption Information
exchange
Request Propose Ask
Require Offer Reply
Order Agree Report
Reject-td Reject-ta Inform

29. 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.

30. Communication Model 30
Typed Message Patterns
INF ORM
AS K
C ommunic ation
type
patterns
1)
2)
RE P LY
3)
ORDE R
RE P ORT
AGRE E
RE P ORT
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 ROP OS E
7)
RE QUE S T
OF F E R RE J E C T-­‐ta
RE QUE S T
8)
P ROP OS 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 "

31. 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

32. 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

33. 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

34. Communication Model 34
Control over messages
■ Refinement of control in communication plan
■ Notations: the same
➤ State diagram
➤ Pseudo code

35. 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

36. 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

37. 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
■ …..

38. 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

39. 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