Social Structures in Tropos

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Social Structures in Tropos
http//www.cs.toronto.edu/km/tropos

• Manuel Kolp Paolo Giorgini John Mylopoulos
• U Louvain U Trento U
  Toronto

First Tropos Workshop, Trento, 15-16 November 2001
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Motivation

• Narrowing the gap between requirements modeling
  and system design
• Same concepts for both phases Social and
  intentional structures
• Coordinated autonomous with goals social
  dependencies
• Concepts from organization theory, and early
  requirements modeling
• Ontology 3 levels (Macro, micro, atomic)

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Social Ontology

• 3 Levels
• 1 Macrolevel Organizational Styles
  (Organization Theory)
• Vertical Integration, Pyramid, Joint Venture,
  Structure in 5, Bidding, Hierarchical
  Contracting, Co-optation, Takeover
• 2 Micro level Social Patterns (Agent, COOPIS
  Community)
• Broker, Matchmaker, Contract-Net, Mediator,
  Monitor, Embassy, Wrapper, Master-Slave, ...
• 3 Atomic Social and intentional concepts i
• goals, actors, social dependencies,

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Organization Theory

• Mintzberg, Scott, Galbraith,
• Studies alternatives and models for (business)
  organizations
• Model the coordination of business stakeholders
  -- individuals, physical or social systems -- to
  achieve common (business) goals.

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Structure in 5

• Operational core basic operations -- the input,
  processing, output associated with running the
  organization.
• Strategic apex executive, strategic decisions.
• Support Assists the operation core for
  non-operational services outside the basic flow
  of operational procedures.
• Technostructure standardizes the behavior of
  other components, help the system adapt to its
  environment.
• Middle line Actors who join the apex to the
  core.

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Structure in 5 and Joint Venture
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Bidding and Vertical Integration
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Structure in 5 in detail (from Mintzberg)
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Formal Analysis
Dependency StrategicManagement Type
SoftGoal Mode achieve Depender
MiddleAgncy Dependee Apex Attribute constant
objective  MiddleAgencyObjective Creation
condition ??objective.strategy trigger
Pursue(objective) Fulfillment condition for
depender ? ma-strategy
MiddleAgencyStrategy (? org -strategy
OrgStrategy (objective.strategystrategy
consistent(ma-strategy,org-strateg
y)) the StrategicManagement dependency is
created when there is no strategy for a given
middle agency objective, and it is fulfilled when
there exists a middle agency strategy consistent
with all the strategies of the organization
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The Mobile Robot Case Study

• Mobile robot activities
• - Acquiring the input from sensors,
• - Controlling the motion of moveable parts,
• - Planning its future path.
• External Factors
• - Obstacles may block the path,
• - Sensor inputs may be imperfect,
• - The robot may run out of power,
• - Mechanical limitations may restrict accuracy
• - The robot may manipulate hazardous materials,
• - Unpredictable events may leave little time for
  responding.

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Conventional Architectures
Control Loop
Task Trees Hierarchies of tasks. Parent tasks
initiate child tasks. Temporal dependencies
between tasks permit selective concurrency.
Layers
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Organizational Architectures Structure-in-5
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Quality Attributes for Mobile Robots

• Coordinativity. A mobile robot has to coordinate
  the actions it undertakes to achieve its
  objective with the reactions forced on it by the
  environment.
• Predictability. For a mobile robot, never will
  all the circumstances of the operation be fully
  predictable. The architecture must provide the
  framework in which the robot can act even when
  faced with incomplete information.
• Failability-Tolerance. Must prevent the failure
  of the robots operation and its environment.
  Local problems like reduced power supply,
  unexpectedly opening doors should not necessarily
  imply the failure of the mission.
• Adaptability. Application for mobile robots
  frequently requires experimentation and
  reconfiguration. Changes in assignments require
  regular modification.

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Strengths and Weaknesses of Robot Architectures
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Coordinativity

• Control loop Simplicity is a drawback when
  dealing with complex tasks, no leverage for
  decomposing the software into more precise
  components.
• Layers services and requests between adjacent
  layers. Transactions not always straight-forward.
  Need to skip layers to coordinate behavior.
• Task trees clear separation of action and
  reaction. Allows incorporation of concurrent
  agents. Components have little interaction with
  each other.
• Structure-in-5 separates data (sensor control,
  interpreted results, world model) from control
  (motor, navigation, scheduling, planning and
  user-level) hierarchies
• Joint venture Components interact via the joint
  manager for strategic decisions. They indicate
  their interest, the joint manager returns them
  such information or mediates the request to other
  partner component.

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NFR Analysis Selecting Architectures
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Mobile Robot Organizational Environment
With the Bidding Style
Bidder
0. task auctionned
Auctioneer
Bidder
Issuer
Bidder
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Using These Social Structures at All Steps

• Early requirements (organization modeling)
  stakeholders (people, organizations, systems),
  goals and dependencies.
• Late requirements, the system-to-be as one or a
  few social actors (blackbox) participating in the
  organization model.

• Architectural design, the system as an
  organization of actors
• Detailed design, system actors transformed into
  agents by means of social patterns
• Implementation Multi-agent system as societies
  of individuals to achieve particular, possible
  common goals.

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Media Industry Early Requirements
Organization Modeling with the Joint Venture Style
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Media Industry Late Requirements
With the Vertical Integration Style
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Media Industry Architectural Design
E-business styles on web, protocols,
technologies Not on business processes, NFRs No
organization of the architecture, conceptual
high-level perspective
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Social Patterns
Mediator
Embassy
Contract-Net
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Detailed Design with Social Patterns
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Conclusion

• System described with concepts from requirements
  and organization modeling
• ? Narrows the gap requirements / design
• Multi-Agent Architectures as social and
  intentional structures
• Best suited to open, dynamic and distributed
  applications
• Ontology on 3 levels
• Macro Organization Styles
• Micro Social Patterns
• Atomic i - goals, actors, social dependencies,

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Discussion Problems, Suggestions ???

• Organization Theory why not Sociology, Group
  Dynamics,
• Formalization at the metalevel Makes sense, not
  too abstract??
• Formal result ex. sound and complete,
  instantiation ethics
• Convincing real-world size case study
  Organization Modeling, Early (Business)
  Requirements
• Styles vs Patterns Macro level lt-gt Microlevel
• Convincing for organization theorists,
  sociologists, ontologists??
• NFR evaluation intuitive vs formal for
  Requirements/Architectures
• WRT Conventional Architectures pros cons,
  reevaluation
• Methodology Social Structures at all steps
  makes sense?