TROPOS

Derived from the Greek  tropé , which means easily changeable , also  easily

adaptable.

Presented By:

Varun Rao Bhamidimarri

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

IntroductionThe 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

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 becausetheir architecture includes goals along with a planning capability for meeting them.

key features (Tropos) Notion of agent and it’s mentalist notion

used in all the phases

Early requirement analysis, precedes prescriptive requirement specification

Based on the Eric Yu’s i* model

Phases Early requirement analysis

- understanding the problem. Late requirement analysis

- describes the system-to-be( functions and qualities).

Architectural design- defines the system’s global architecture in terms of subsystems.

Detailed design- defines the behavior of each component in

detail.

Example Media Shop Case Study

store for selling and shipping media items like books, magazines, CD’s 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

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

Early requirements analysis

Stakeholder Goal (dependum)

Depender

Dependee

depender -> dependum -> dependee

Strategic dependency model

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.

softgoal

goal

task

resource

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.

Strategic rationale model 4 types of nodes:goal, task, resource, softgoal

2 types of links:means-ends, decomposition.

Strategic rationale model (cont..)

Means-end link

Decomposition link

Architectural design Constitutes a model of system

structure, which describes how system components work together.

use “organizational styles” to describe the system architecture.

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.

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.

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.

Formal Tropos – Outer layer

mode

attribute

Formal Tropos – Inner layer

Cardinality constrain

actor constrain

Instance creationTask is performed

Formal Tropos verificationT-Tool Can be verified in order to identify:

Errors Ambiguities Under-specifications

Uses the T-Tool to support the verification process.

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.

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.

Formal Tropos verificationT-Tool (Cont ...) Assertion properties: Verify weather the requirements are

under-specified and allowing for invalid senarios.

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

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.

Organizational Structure :(Structure – in – 5 )

Proposed by Minztberg5 sub-structures: Operational Code – carries out the basic

tasks and procedures. Strategic Apex – makes all executive

decisions and defines overall strategy.

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

Structure – in – 5 (Cont..) Support – provides specialized services

E.g. cafeteria, R&D, legal counsel

Structure – in – 5 (Cont..)

Operational Core

Strategic apex

Support

Middle Line

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.

Strategic Alliances (Cont..) E.g. Joint Venture Style:

Involves agreement between two or more partners to obtain benefits of larger scale.

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.

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

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.

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”.

Goal Models Traditional goals consists of AND/OR

decomposition.

Unfortunately these well defined relationships cannot be applied for many domains:

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 don’t guarantee the satisfaction of the goal.

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

Goal Model ExampleA partial goal model for GM

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.

Comparison with MASE

TROPOS MASEEmphasis 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

Questions? OR Comments?

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