TROPOS

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TROPOS

• Derived from the Greek  tropé , which means
  easily changeable , also  easily adaptable.

Presented By Varun Rao Bhamidimarri
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Overview

• Introduction
• Key Features of TROPOS.
• Phases.
• Organizational Structure.
• Strategic Alliances.
• Social Patterns.
• Goal Model.
• Conclusion.

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Introduction

• The explosive growth of application areas such as
  electronic commerce, enterprise resource
  planning, and peer-to-peer computing has deeply
  and irreversibly changed our views on software
  and Software Engineering.
• Softwares now need to be
• based on open architectures
• continuously change and evolve
• operate on different platforms
• Robust, autonomous, capable of serving end users
  with a minimum of overhead and interference

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Introduction (cont..)

• For these reasons and more agent-oriented
  software development is gaining popularity over
  traditional software development techniques
• provide for an open, evolving architecture that
  can change at run-time to exploit the services of
  new agents, or replace under-performing ones.
• Can cope with unforeseen circumstances because
• their architecture includes goals along with a
  planning capability for meeting them.

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key features (Tropos)

• Notion of agent and its mentalist notion used in
  all the phases
• Early requirement analysis, precedes prescriptive
  requirement specification
• Based on the Eric Yus i model

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Phases

• Early requirement analysis
• - understanding the problem.
• Late requirement analysis
• - describes the system-to-be( functions and
  qualities).
• Architectural design
• - defines the systems global architecture in
  terms
• of subsystems.
• Detailed design
• - defines the behavior of each component in
• detail.

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Example

• Media Shop Case Study
• store for selling and shipping media items like
  books, magazines, CDs etc.
• 4 actors
• Media shop B2C internet site.
• Media shop customers use the catalogue provided
  to fill their orders.
• Media supplier supplies the in-catalogue items
• Media producer supplies latest releases

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Requirement Analysis

• Early requirements
• why the system is being developed
• capture the intentions of the stakeholders and
  model them as goals
• uses the strategic dependency model

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Early requirements analysis
Strategic dependency model
Stakeholder Goal (dependum)
Dependee
Depender
depender -gt dependum -gt dependee
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Early requirements (cont..)

• 4 types of dependencies
• goal delegation of responsibility
• softgoal similar to goals, but cannot be
  defined precisely.
• task dependee is required to perform certain
  activity.
• Resource provide resource to the depender.

goal
softgoal
task
resource
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Late Requirements analysis

• Describes functional and non-functional
  requirements of the system-to-be.
• Represented as one or more actors who contribute
  to the fulfillment of stakeholders goals.
• Uses the Strategic Rational Model.

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Strategic rationale model

• 4 types of nodes
• goal, task, resource, softgoal
• 2 types of links
• means-ends, decomposition.

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Strategic rationale model (cont..)
Means-end link
Decomposition link
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Architectural design

• Constitutes a model of system structure, which
  describes how system components work together.
• use organizational styles to describe the
  system architecture.

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Detailed Design

• Has details of each architectural component of a
  system.
• determines how the goals assigned to each actor
  are fulfilled by agents in terms of design
  patterns.
• describes agent communication and behavior.

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Formal Tropos

• Verification of requirements specifications.
• Focuses not only on the intentional elements but
  also the conditions in which they arise.
• describes actors, goals, dependencies of the
  domain and their relationship.

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Formal Tropos (Cont..)

• Two layers
• Outer layer similar to a class declaration.
• Associates attributes to elements.
• Inner layer
• expresses constrains on the lifetime of the
  objects.

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Formal Tropos Outer layer
attribute
mode
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Formal Tropos Inner layer
actor constrain
Cardinality constrain
Instance creation
Task is performed
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Formal Tropos verificationT-Tool

• Can be verified in order to identify
• Errors
• Ambiguities
• Under-specifications
• Uses the T-Tool to support the verification
  process.

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Formal Tropos verificationT-Tool (Cont ...)

• Provides several verification functionalities
• Animation allows for an immediate feedback on
  the effects of constraints and for an early
  identification of trivial bugs and missing
  requirements.

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Formal Tropos verificationT-Tool (Cont ...)

• Consistency checks checks to see if the
  constrains are not self contradictory.
• Possibility checks verifies whether we have
  ruled out scenarios expected by the stakeholders.

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Formal Tropos verificationT-Tool (Cont ...)

• Assertion properties
• Verify weather the requirements are
  under-specified and allowing for invalid
  senarios.

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Socially based MAS Architectures

• Since the fundamental concept of MAS (multi
  agent system) is intentional and social, tropos
  uses the following
• Organizational Theory
• Strategic Alliances

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Organizational Theory(architectural design)

• Describes how practical organizations are
  structured.
• How new ones can be structured
• How old ones can be changed to improve
  effectiveness.
• E.g. pyramid style, chain of values, matrix,
  bidding style etc.

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Organizational Structure (Structure in 5 )

• Proposed by Minztberg
• 5 sub-structures
• Operational Code carries out the basic tasks
  and procedures.
• Strategic Apex makes all executive decisions
  and defines overall strategy.

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Structure in 5 (Cont..)

• Middle Line establishes hierarchy of authority
  between the strategic apex and the operational
  core.
• Consists of managers.
• Technostructure makes others work effective by
  standardizing
• Processes, outputs and skills

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Structure in 5 (Cont..)

• Support provides specialized services
• E.g. cafeteria, RD, legal counsel

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Structure in 5 (Cont..)
Strategic apex
Middle Line
Support
Operational Core
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Strategic Alliances

• Links specific facets of two or more
  organizations.
• Enhances the effectiveness of participant
  organizations, by mutually beneficial trade of
  technologies, skills or products.

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Strategic Alliances (Cont..)

• E.g. Joint Venture Style
• Involves agreement between two or more partners
  to obtain benefits of larger scale.

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Social patterns (detailed design)

• Specifies how the goals delegated to each actor
  are fulfilled.
• Is guided by a catalogue of multi-agent patterns,
  which offer a set of standard solutions.
• Social patterns focus on the social aspects in
  multi-agent systems.

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Social patterns (Cont..)

• 2 categories
• The pair pattern describes direct interaction
  between the agents. Such as
• Booking, call-for-proposal, subscription etc.
• E.g. Bidding pattern involves initiator and no of
  participants. He organizes and leads the bidding
  process

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Social patterns (Cont..)

• Mediation pattern
• Features a intermediary agent that helps other
  agents to reach an agreement on exchanging
  services such as
• Monitor, broker, matchmaker, mediator, embassy
  etc.
• E.g. Broker pattern intermediary between the
  provider and the consumer.

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Social patterns (Cont..)

• In our example of Media Store
• Shopping cart booking pattern (reserves
  available items).
• Information broker (broker pattern) between the
  Shopping cart and the Product Database.

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Goal Models

• Traditional goals consists of AND/OR
  decomposition.
• Unfortunately these well defined relationships
  cannot be applied for many domains

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Goal Models (Cont..)

• E.g. Highly Reliable System
• Cannot be defined formally
• thoroughly debugged system and thoroughly
  tested system contribute to the satisfaction,
  but it is only partial.
• They dont guarantee the satisfaction of the
  goal.

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Goal Models (Cont..)

• Tropos proposes a formal model for the goal
  graph.
• Objectives are represented as goals and analyzed
  using goal relationships like
• AND, OR
• -/ (partial) denial/satisfaction
• --/ (sufficient) - denial/satisfaction

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Goal Model Example
A partial goal model for GM
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Conclusion

• Distinguishing feature
• Emphasis on requirement analysis.
• Lacks tool support for transition between phases.
• Has been applied only to modest size case
  studies, not to full fledged multi agent
  systems.

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Comparison with MASE
TROPOS MASE
Emphasis on early requirement analysis. Uses goal hierarchy to capture requirements.
Tropos provides Formal Tropos to verify requirements. No formal language support
No proper tool support Provides tool support (agentMom)
Tropos uses Organization Theory and Social Patterns for to capture system interactions. Uses role model and the concurrent task diagram.
Not been applied to full fledged multi agent systems Has been applied to many graduate and research level projects with very good results
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Questions? OR Comments?

• ..