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Tropos Research
Overview:
RWTH Aachen
M. Jarke and G. Lakemeyer
RWTH Aachen
RWTH Aachen
Computer Science V
TROPOS Workshop, Trento, November 15-16, 2001
History of Aachen’s Approach
DAIDA : Metadata linking IS development phases,
development of Telos, first ConceptBase
prototype (1988)
COMPULOG : logical foundations of meta
modeling, meta formula handling by partial
evaluation (Jeusfeld 1992)
NATURE/CREWS : application to perspective
resolution in requirements engineering and
business modeling (Nissen 1997, Peters 1997),
extension to business cooperation (Kethers
2001) and warehoues/e-commerce (Quix 2002)
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TROPOS : dynamic modeling of social networks in
coooperation with sociologists and entrepreneurs
TROPOS Workshop, Trento, November 15-16, 2001
Multi-Perspective Cooperative Modeling :
Metamodels as Goals
common
meta model
entity
relationship
notation
data
flow
notation
viewpoint 1
viewpoint 2
For small processes [Nissen et al.; IEEE SW 96]:
i
--> metaplan + repository formalization
Fornlarge processes [Rose, CACM 12/98]:
--> layout generation + synchronization
analysis
common reality
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TROPOS Workshop, Trento, November 15-16, 2001
Regional Networks in the US
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Emilio J. Castilla, Hokyu Hwang, Ellen Granovetter, and
Mark
Granovetter
(2000):
TROPOS
Workshop,
Trento, November
15-16, 2001
Network of Silicon Valley Entrepreneurs
Network Theory Approaches
• Cluster Theory (M. Porter)
• Innovation and productivity by Coopetition
• Social Capital (Bourdieu, Putnam)
• Reputation mechanisms (individual / organisation)
• central role of trust
• our TCD approach (Trust-Confidence-Distrust)
• networks not a hybrid
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• distrust is not negation of trust
• successful combination high trustTROPOS
- high
distrust !
Workshop, Trento, November 15-16, 2001
Entrepreneurship Network Route 128,
dependencies according to 40 interviews
Investment
Banker
Strategic
investor
Limited
Venture
Partners
Capitalist
Angel
Group Angel
Entrepreneur
lawyer
customer
Local Cluster Information Technology
Supply/
Service
Consultant/
Mediator
Team
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50kE-Center
Competition
E-Lab
Faculty
Alumni
Licensing
Office
TROPOS Workshop, Trento, November 15-16, 2001
Modeling Organisation
Networks with Tropos:
A Trust-Centered Approach
M. Jarke and G. Lakemeyer
Aachen University of Technology
other contributors:
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L. Ellrich, C. Funken, M. Meister, Freiburg
G. Gans, S. Kethers, R.Klamma, T. Vits, Aachen
V. Wulf, Fraunhofer FITTROPOS Workshop, Trento, November 15-16, 2001
Goal- and Scenario-Based
Continuous Requirements Management
observation focus/
goal discovery
scenario generation
for validation/
refinement
goal/requirement
refinement/negotiation
initial
model
change
specification
animate
reverse
analysis
current
scenario
change
envisionment
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future
scenario
change
implementation
capture
existing
system
new
model
legacy
integration
new
system
... extended to Social Networks
TROPOS Workshop, Trento, November 15-16, 2001
Social Networks
• an autonomous form of coordination that
combines advantages of two traditional mechanisms
• markets: flexibility, adaptive to competition
• hierarchies: long duration cooperation
• trusting cooperation of autonomous, but
interdependent agents (here: organizations)
• small-business B2B commerce, virtual org‘s
• entrepreneurship networks
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TROPOS Workshop, Trento, November 15-16, 2001
Overview
1. Role of Trust/Distrust in Agent Networks
2. A Multi-Perspective Modeling Approach
3. The Tropos(AC) Prototype
4. Conclusions
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TROPOS Workshop, Trento, November 15-16, 2001
Trust
risky investment
•
•
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expectation of
reciprocity
individual trust : likelihood of reciprocity violation
– Coleman: p G > (1-p) L (similar: DAI community)
– game theory: iterated prisoner‘s dilemma
– eBusiness: reputation mechanisms
network confidence : strategic vulnerabilities, balanced
inter-dependency networks
TROPOS Workshop, Trento, November 15-16, 2001
An Example: Seminar Organization
Eric Yu‘s i*,here: the strategic rational model
Distrust
• Distrust is not just negation or absence of
trust
– Luhmann 1988: functional equivalence + distrust spiral
– Kern 1997: inject controlled amount of distrust
– Lewicki et al. 1998: high-trust / high-distrust networks
can be highly successful
• Implications for RE
– disparity between motive and action (latency)
– positive function in networks (watchful trust)
– tendency for distrust aggregation must be contained,
e.g. by network rules and traceability (institutionalized
distrust)
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• A Basis for IT-supported continuous RE !
TROPOS Workshop, Trento, November 15-16, 2001
The TCD Model :
a delicate balance for network success
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TROPOS Workshop, Trento, November 15-16, 2001
Overview
1. Role of Trust/Distrust in Agent Networks
2. A Multi-Perspective Modeling Approach
3. The Tropos(AC) Prototype
4. Conclusions
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TROPOS Workshop, Trento, November 15-16, 2001
Enhance Viewpoint Resolution Methods:
But which Viewpoints are needed?
Expectations
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+
Reality
... communicated in
negotiations among
agents
Reaching goals
requires certain actions
Speech
Acts
Plans
depend on (and influence) Trust, Confidence, Distrust
TROPOS Workshop, Trento, November 15-16, 2001
Multi-Perspective Agent Model:
The TCD Kernel
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TROPOS Workshop, Trento, November 15-16, 2001
Multi-Perspective Agent Model:
Structural Perspectives
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TROPOS Workshop, Trento, November 15-16, 2001
Multi-Perspective Agent Model:
Action Perspectives
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TROPOS Workshop, Trento, November 15-16, 2001
Speech Act Perspektive
Action Workflow [Medina-Mora et al. 1992, Schäl 96]
Delegation within Speech Acts
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TROPOS Workshop, Trento, November 15-16, 2001
Speech Act Modeling:
TCD influences delegation structure
No trust:
Pro‘s:
no risk
Con‘s:
narrow
competence
Speech Act Modeling:
TCD influences delegation structure
Trust:
Pro‘s:
broader
competence
Con‘s:
delayed
reaction
Speech Act Modeling:
TCD influences delegation structure
Confidence:
Pro‘s:
improved
competence
and efficiency
Con‘s:
higher risk
Speech Act Modeling:
TCD influences delegation structure
Confidence plus Distrust:
Pro‘s:
focused risk
management
Con‘s:
monitoring effort
Extending i* for a Trust-Based Approach
• Task preconditions and postcondition
– synchronization of interdependent agent-plans
• Trust, confidence, and distrust as subj. probabilities
– as part of preconditions they control task selection
• A simple (linear) model of time
– monitoring expectations (distrust, network rules)
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 Facilitates the mapping into an
executable plan language
TROPOS Workshop, Trento, November 15-16, 2001
Organizer´s Plan with Confidence
Client
Organizer
Speaker
Watchful Confidence
Overview
1. Role of Trust/Distrust in Agent Networks
2. A Multi-Perspective Modeling Approach
3. The Tropos(AC) Prototype
4. Conclusions
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TROPOS Workshop, Trento, November 15-16, 2001
From Extended i* to Congolog programs
Congolog: A logic-based plan language
• offers control constructs like sequences, if-then-else,
while, recursion, and concurrency
• allows reasoning about actions with a solution to the
frame problem (Reiter 1991)
• comes equipped with an interpreter for simulation
Example:
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proc sem_org
<c,l,t.request(c,l,t) 
/* client c requests seminar l to be held at time t */
if nettrust(c)  NWThreshold
then (commit(c,l,t); organize(c,l,t))
else /* call a proc. to find speaker first and then commit */
end proc
TROPOS Workshop, Trento, November 15-16, 2001
The System Architecture
OME
ext. i*
static model
Telos file
Golog prog.
.pl file
Eclipse
Golog Int.
Java Interf.
TCP/IP
CBase
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History
Simulator
(Java)
TROPOS Workshop, Trento, November 15-16, 2001
A Restaurant Domain
everything_
ok
rate_
meal
eating_
finished
something_
not_ok
exogenous
rate_ bad
bad_rating
go_to_
restaurant
ready
trust_high_
enough
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good_rating
meal
eat
start
rate_
good
guest
choose_
meal
serve_
meal
work
meal_
chosen
accept_
order
waiter
meal
cook
order_
received
chef
TROPOS Workshop, Trento, November 15-16, 2001
The Extended i* Editor OME
exogenous
guest
waiter
chef
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TROPOS Workshop, Trento, November 15-16, 2001
Congolog Code generated from ext. i*
/*Agent procedures */
proc(agent_guest,
conc( interrupt(eating_finished=true , decomp_rate_meal),
interrupt(ready=true , decomp_go_to_restaurant))).
proc(agent_chef,interrupt(order_received=true , cook)).
proc(agent_waiter, interrupt(meal_chosen=true , decomp_work)).
/*Decomposition of complex Tasks*/
proc(decomp_work ,[ conc(accept_order , serve_meal), work]).
proc(decomp_go_to_restaurant ,[ conc(choose_meal , eat),
go_to_restaurant]).
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proc(decomp_ rate_meal ,[ conc([rate_bad , rate_meal] ,
[rate_good , rate_meal])]).
TROPOS Workshop, Trento, November 15-16, 2001
Simulator 1
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TROPOS Workshop, Trento, November 15-16, 2001
Simulator 2
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Simulator 3
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TROPOS Workshop, Trento, November 15-16, 2001
Conclusions
• worked with sociologists to look into the dynamics of
how dependencies and strategic rationals change due
to the evolution of trust and distrust in a social
network
• Introduced methodology based on i*, ConGolog, and
speech acts to model and simulate trust-based interactions in agent networks. Have first prototype.
• To evaluate our model, we are studying networks of
start-up companies, in Germany and the US (MIT).
Also look at b2b applications (M. Schoop, T. List).
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• Interested in understanding relationships to other
formalizations (model-checking) and applications.
TROPOS Workshop, Trento, November 15-16, 2001