TROPOS Derived from the Greek trop which means

TROPOS Derived from the Greek tropé , which means easily changeable , also easily adaptable. Presented By: Varun Rao Bhamidimarri

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

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

Introduction (cont. . ) For these reasons and more agent-oriented software development is gaining popularity over traditional software development techniques n n 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.

key features (Tropos) n n n 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 n n 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: n Media shop – B 2 C internet site. n Media shop customers – use the catalogue provided to fill their orders. n Media supplier – supplies the in-catalogue items n Media producer – supplies latest releases n

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

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

Early requirements (cont. . ) n goal 4 types of dependencies n goal – delegation of responsibility n softgoal – similar to goals, but cannot be defined precisely. softgoal n task – dependee is required to perform certain activity. task n Resource – provide resource to the depender. resource

Late Requirements analysis n n n 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 n 4 types of nodes: goal, task, resource, softgoal n 2 types of links: means-ends, decomposition.

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

Architectural design n n Constitutes a model of system structure, which describes how system components work together. use “organizational styles” to describe the system architecture.

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

Formal Tropos n n n 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: n Outer layer – similar to a class declaration. n Associates attributes to elements. n Inner layer n expresses constrains on the lifetime of the objects.

Formal Tropos – Outer layer attribute mode

Formal Tropos – Inner layer actor constrain Task is performed Instance creation Cardinality constrain

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

Formal Tropos verification T-Tool (Cont. . . ) n Provides several verification functionalities: n Animation – allows for an immediate feedback on the effects of constraints and for an early identification of trivial bugs and missing requirements.

Formal Tropos verification T-Tool (Cont. . . ) n n 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 verification T-Tool (Cont. . . ) n n Assertion properties: Verify weather the requirements are underspecified and allowing for invalid senarios.

Socially – based MAS Architectures n Since the fundamental concept of MAS (multi – agent system) is intentional and social, tropos uses the following : n n Organizational Theory Strategic Alliances

Organizational Theory (architectural design) n n 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 Minztberg 5 sub-structures: n Operational Code – carries out the basic tasks and procedures. n Strategic Apex – makes all executive decisions and defines overall strategy.

Structure – in – 5 (Cont. . ) n n Middle Line – establishes hierarchy of authority between the strategic apex and the operational core. n Consists of managers. Technostructure – makes others work effective by standardizing n Processes, outputs and skills

Structure – in – 5 (Cont. . ) n Support – provides specialized services n E. g. cafeteria, R&D, legal counsel

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

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

Strategic Alliances (Cont. . ) n E. g. Joint Venture Style: n Involves agreement between two or more partners to obtain benefits of larger scale.

Social patterns : (detailed design) n n n 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: n The pair pattern : describes direct interaction between the agents. Such as: n Booking, call-for-proposal, subscription etc. n E. g. Bidding pattern involves initiator and no of participants. He organizes and leads the bidding process

Social patterns (Cont. . ) n Mediation pattern: n Features a intermediary agent that helps other agents to reach an agreement on exchanging services such as n Monitor, broker, matchmaker, mediator, embassy etc. n E. g. Broker pattern – intermediary between the provider and the consumer.

Social patterns (Cont. . ) n In our example of Media Store: n n Shopping cart – booking pattern (reserves available items). Information broker (broker pattern) – between the “Shopping cart” and the “Product Database”.

Goal Models n n 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” n Cannot be defined formally n “thoroughly debugged system” and “thoroughly tested system” – contribute to the satisfaction, but it is only partial. n They don’t guarantee the satisfaction of the goal.

Goal Models (Cont. . ) n n Tropos proposes a formal model for the goal graph. Objectives are represented as goals and analyzed using goal relationships like: n AND, OR n -/+ (partial) – denial/satisfaction n --/++ (sufficient) - denial/satisfaction

Goal Model Example A partial goal model for GM

Conclusion n Distinguishing feature: n 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 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 (agent. Mom) 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? n …. .