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Communication Model

The Communication Plan
Specifying agent-agent transactions
Transaction patterns

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 2

Relation to other models

task selected in feasibility study communica tion
requirements
and further detailed in mode l
specification
Task and Agent Models for interaction functions

orga niz a tion mode l
ta s k mode l knowledge- de s ign
a ge nt mode l intensive mode l
task

requirements
specification
knowle dge
for reasoning functions
mode l


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 Agent Model

Tas k Agent
Focuses on I/O info objects capabilities
..... .....
modeling the involved-in involved-in

dialogue between
Information
agents Communication
Plan
part-of
Trans action

identifier/name
part-of
Exchange
Specification
I/O info objects
agents involved communication type
dialogue diagram communication plan message content
transaction control constraints message control
info exchange spec info form/medium

involved-in
Structured, semi-
formal approach Tas k s tructure

transfer functions
.....

Knowledge Model


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

kWh kWh
utility
utility customer
customer utility
utility & customer
customer
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
Agent A Dialogue Agent B
(e.g. us er) (e.g. s ys tem)
Note: agent's Task A1 Task B1
(leaf) tasks Transaction
Tr. 1
are key entry Task B2

to dialogue Task A2 Transaction
Tr. 2
diagram
Task A3
construction Transaction
Tr. 3
Task A4
Task B3
Transaction
Tr. 4

Task A5 Task B4


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
Utility Cus tomer

Task and Announce
Express
Preferences
transaction links in
power auction are C Bid
O
graphically Assess M
sketched in the M
U
dialogue diagram: Award
N
I
C
A
Gives overview of Schedule T
E
the system's Implement
communication
plan
Monitor Monitor


CP for the housing application

assessment finished/
report decision

application data needed/ask
assessment
application received/
order assessment
waiting for
case data
data received / reply


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

Reduction need?
Announce & Kick-off

Auction Auction Completed/
Running Awards Distributed
Next Round
Award & Present
Interested? N Interested? Y Convergence? N
Convergence? Y
Opt out Express Prefs.

Preferences Allocation
Opted Out
Calculated Computed

Power need? Assess
Bid & Submit
Bids received?

Bid
Submitted


Middle Level

identifier
& name
agents communication
involved plan
Specification of individual
transactions, structured in
a number of components:
TRANS-
ACTION

Simple worksheet
techniques are helpful
here constraints information
objects
information exchange
specification


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 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.


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?


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 Information
exchange
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

Not only typing of single messages possible.
Also, natural chains of message types can be formed (cf. COSY):
Communication type patterns
Communication Patterns
INFORM ORDER REQUIRE REQUEST

1) REPORT AGREE REJECT-ta PROPOSE OFFER REJECT-ta

3) 5) 7)

ASK AGREE OFFER PROPOSE

REPLY REPORT ORDER REJECT-td REQUEST REQUIRE REJECT-td

2) 4) 6) 8)


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 Auction-data-message
type:PROPOSE type: INFORM
content: bid content: market data
from: customer agent from: auctioneer
to: auctioneer to: customer agent
Opt-out-message Next-round-message
type: REJECT-TA type: REQUEST
content: no part content: trigger next round
from: customer agent from: auctioneer
to: 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


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07 communication

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