Integration of System Requirements and MultiAgent Software Architecture

1
Integration of System Requirements and
Multi-Agent Software Architecture

• Lúcia Rosangela David Bastos
• Jaelson Freire Brelaz de Castro

August, 2005
2
Contents

• Motivation
• Organizational Theory in MAS
• The Tropos Project
• The Bank Example
• The SIRA Framework
• Final Considerations

3
Motivation

• Semantic Gap among Requirements and Architecture
• Requirements are derived from concepts and
  relationships in the problem domain (for example,
  e-commerce, bank accounting) and architecture
  models are solution for the problem described in
  the requirements
• This conceptual differences between what to do
  (requirements) versus how to do (architecture)
  is one of the challenging problem in software
  engineering
• Goal-based Organizational Models
• Goals can be related to functional abilities,
  business and system qualities
• Goals can be used as starting point to construct
  the architectural description

Index
4
Organizational Concepts

• Organizations are social groups that are
  goal-directed and have a set of structured
  activities to achieve their goals.
• A social group is an organization unit with a set
  of organized members being involved in social
  relationships, pursuing common goals for some
  period of time with an identifiable domain
• Actor is a individual with intentional
  properties, such as, goals, beliefs, abilities
  and compromises. Actors may be people, agents
  (software) or organizations.
• Agents may become members of such an
  organizational group, if they succeed to
  undertake one or more roles that contribute
  towards the collective objectives.
• Role is an abstract representation of the
  behavior of actor(s) that perform similar
  functions in a group

5
Organizational Concepts
Index

• SIRA Framework uses Organizational concepts
• Organizational group consist of a set of
  sub-groups.
• A sub-group represents a context of a role.
• A organizational domain can define the roles of
  various actors.
• Responsibilities are defined in terms of goals
  and tasks

Multi-agent system organization of members to
achieve particular, possible common goals.
6
Tropos Project
Index
Ontology
Actors, social dependencies, goals, resources,...
Application area
(Requirements-driven) Software development
TROPOS
i
SIRA Framework
Detailed design
Early requirements
Architectural design
Late requirements
Tropos, in Greek, means manner (as in manner
of doing things)
7
The Bank Example
Index

• Organizational chat of a bank example, which
  describes a strict partially set of named
  positions and roles.
• Bank is an organization that holds money
  belonging to others, investing and lending it to
  get more money.

8
Systematic Integration between Requirements and
Architecture - SIRA Framework
Index
NFR Framework
Architectural catalogue
Organisational Model Specification
Assignment Model Definition
Architectural Configuration
Requirements models
Organisational Model Architectural Style
Assignment Model
Architectural Configuration
Sequence
9
i an Organizational Modeling Framework

• Early requirements (organization modeling)
• these concepts are used to model external
  stakeholders (people, organizations, existing
  systems), their relevant goals and
  inter-dependencies.
• Late requirements
• Resource, task and softgoal dependencies
  correspond naturally to functional and
  non-functional requirements.
• Functional Goals are generally operationalized
  during Late Requirements

SIRA
10
The Bank Example in i notation
Index
SIRA
11
The Bank Example in i

• Banks act as intermediaries between the people
  who have money to hold and those who depend on
  money for business transactions.
• Bank Actor depends on the Customer's money
  (represented as resource Money) for investment,
  and depends on Customer to request loans
  (represented as goal Get Loan) and to earn more
  money (represented as softgoal Profitability).
• Customer depends on Bank to hold his money in
  deposit or savings account (represented as goal
  Deposit Money), and to earn a certain amount of
  money called interest for depositing his money in
  a bank (represented as softgoal Deposit
  Profitability). He lets the bank use the money
  for new investments.

12
Architectural Catalogue

• Multi-Agent Architecture as Social Structures
• Global Architecture in terms of interconnected
  social components.
• Concepts from organization theory (Mintzberg,
  Scott, Galbraith, )
• 3 levels
• 1 Macro level Organizational Styles
  (Organization Theory)
• Vertical Integration, Pyramid, Joint Venture,
  Structure in 5, Bidding, Hierarchical
  Contracting, Co-optation, Takeover
• 2 Micro level Patterns (Broker, Matchmaker,
  Contract-Net, Mediator, Monitor, Embassy,
  Wrapper, Master-Slave, )
• 3 Atomic Social and intentional concepts

SIRA
13
Structure in-5 Style
Strategic and logistic components found in
organizations.

• 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.
• Coordination standardizes the behavior of other
  components, help the system adapt to its
  environment.
• Middle Agency Actors who join the apex to the
  core.

SIRA
14
Joint Venture Style

• Based on a agreement between two or more
  principal partners.
• Principal Partner Autonomous on a local
  dimension and interacts directly with other
  principal partners to exchange services, data and
  knowledge
• Joint Management actor coordinates tasks and
  manages the sharing of knowledge and resources.
• Secondary Partners Supply services or support
  tasks for the organization core

SIRA
15
Architectural Catalogue and Quality Attributes
Predictability, Security, Adaptability,
Cooperativity, Competitivity, Availability,
Integrity, Modularity, Aggregability
() contributes positively (very positively)
- (--) contributes negatively (very negatively)
SIRA
16
The Organizational Model
Index

• Organisational concepts
• Organisation is a group. It consist of a
  collection of sub-groups. A Sub-group represents
  a context of a role. A organisational structure
  can define the roles of various members (actors).
  
• Roles corresponds to the division of labour
• Members corresponds to a set of agent in the
  group
• Responsibilities are defined in terms of goals
  and tasks
• Multi-Agent System corresponds to a group
• Organizational Meta-model

SIRA-OM
17
The Organizational Meta Model
Index

• Extension of the i Meta-model in Telos

SIRA-OM
18
The Organizational Model Specification
Index
Requirement model
Role Identification
Organizational Model
Goal/Task Refinement
Architectural Selection
Architectural Style
Sequence
NFR Framework
Architectural catalogue
SIRA
19
Organizational Model Goal/Task Refinement

• Bank Group is a Multi-Agent System
• Main Responsibilities (Goals)
• Services and capabilities assigned to a Group.
  Responsibility is extracted from the goals to be
  fulfilled by system actors, like Get Loan or
  Deposit Money

SIRA-OM
20
Goal/Task Refinement - Get Loan

• Means-end analysis - The goal Get Loan is
  achieved through the task Lending Money.
• The task is achieved through the sub-tasks
  Customer Profile Management, Loan Request
  Analysis and Loan Account Management

New Profile
Customer Profile Management
Update Profile
Credit Analysis
Loan Request Analysis
Lending Money
Payment Analysis
Get Loan
New Loan Account
Loan Balance
Loan Account Management
Accounting
Strategic Analysis
SIRA-OM
21
Goal/Task Refinement Deposit Money

• Means-end analysis - The goal Deposit Money is
  achieved through the task Account Management.
• The task is achieved through the sub-tasks
  Customer Profile Management, New Account and
  Account Transaction and Accounting

SIRA-OM
22
Organizational Model Role Identification

• Role Identification involves the distribution of
  tasks to perform a group goal, like Get Loan or
  Deposit Money

SIRA-OM
23
Role Identification Get Loan

• Role Identification involves the distribution of
  tasks to perform a group goal

New Profile
Customer Profile Management
Update Profile
Credit Analysis
Loan Request Analysis
Lending Money
Payment Analysis
Get Loan
New Loan Account
Loan Transactions
Loan Account Management
Accounting
Strategic Analysis
24
Role Descriptions Get Loan

• The Goal Get Loan is performed with a set of six
  roles

25
Role Interactions Get Loan

• Social Graph - Interaction sequence of roles
  played to fulfil a group goal

26
Matrix Representation Get Loan

• Get Loan - Matrix representations
• The sender is the row (out degree)
• The target is the columns (in degree)

27
Role Identification Deposit Money
28
Role Description Deposit Money

• The Goal Deposit Money is performed with a set of
  six roles

29
Role Interaction Deposit Money

• Social Graph - Interaction sequence of roles
  played to fulfil a group goal

30
Matrix Representation Deposit Money

• Deposit Money - Matrix representations
• The sender is the row (out degree)
• The target is the columns (in degree)

31
Organizational Model - Architectural Selection

• Architectural Properties
• Each architecture must conform to the application
  domain qualities
• Each architectural candidate will be analyzed
  based on positive contributions to priority
  qualities (constraints) of the application domain
• NFR Framework
• Each architectural candidate will be analyzed
  based on positive contributions to priority
  qualities (constraints) of the application domain
• Selecting an Architectural Style

SIRA-OM
32
Architectural Alternatives of the Bank Example

• Architectural Properties (NFR Framework)
• Security
• Availability
• Integrity
• Selected Architecture - Structure-in-5 Style

() contributes positively (very positively)
- (--) contributes negatively (very negatively)
SIRA-OM
33
Organizational Elements of the Bank Example

• Roles, Interactions and Architectural Style

SIRA
SIRA-OM
34
The Assignment Model Definition
Index
Sequence
SIRA
35
Assignment Model Centrality Analysis

• The Centrality of Actors
• The extent to which an organization revolves
  around an actor
• The star network
• Two aspects to describe the location of actors in
  terms of how close they are to the center in a
  organizational structure
• Degree Centrality (influence and prominence)
• Closeness Centrality (importance of a position
  near to the center)
• Centrality analysis Bank Example (Get Loan and
  Deposit Money)
• Architecture
  (Structure-in-5 and Joint Venture)

SIRA-AM
36
Centrality Analysis Bank Example - Get Loan

• Degree Centrality
• Influential (out degree)
• Prominent (in degree)
• Closeness Centrality
• The distance of an actor for all other - inverse
  of the geodesic distance (farness) and normalized
  relative to the most center actor ( g-1 )

37
Centrality Analysis Bank Example Deposit
Money

• Degree Centrality
• Influential (out degree)
• Prominent (in degree)
• Closeness Centrality
• The distance of an actor for all other - inverse
  of the geodesic distance (farness) and normalized
  relative to the most center actor ( g-1 )

38
Centrality Analysis Structure-in-5 Style

• Social Graph and Matrix
• Degree Centrality
• Influential (out degree)
• Prominent (in degree)
• Closeness Centrality
• The distance of an actor for all other - inverse
  of the geodesic distance (farness) and normalized
  relative to the most center actor ( g-1 )

39
The Social Graph - Structure-in-5 Style
Social Graph from i model with two more
relations
40
Matrix Representation Structure-in-5 Style
41
Centrality Analysis Joint-Venture Style

• Social Graph and Matrix
• Degree Centrality
• Influential (out degree)
• Prominent (in degree)
• Closeness Centrality
• The distance of an actor for all other - inverse
  of the geodesic distance (farness) and normalized
  relative to the most center actor ( g-1 )

42
The Social Graph - Joint-Venture Style
Social Graph from i model with two more
relations
Contractual activity
43
Matrix Representation Joint-Venture Style
44
Assignment Model Cluster Analysis

• Cluster is a technique to identify natural groups
  within the data set.
• The Cluster analysis is a way to grouping roles
  into sub-group. The roles are analyzed using two
  techniques
• The Centrality Measures
• The centrality analysis indicates the extend to
  which a group is organized around its most
  central actor
• The Degree of Structural Equivalence
• The similarity matrix indicates the extend to
  which two actors have the same profile of
  relations to all other actors in the group.
• Cluster Analysis of the Bank Example

SIRA-AM
45
Cluster Analysis Centrality Measures

• The first step is to measure the overall
  integration of the group
• The degree is measured using by computing the
  difference between the centrality scores of the
  most central point and those of all other point.
• In the Bank Example
• the actors Loan Manager and Profile Manager are
  the most central actors
• They have partial similarity in the centrality
  results
• Similar relations with others actors
• Related degree centrality (out degree 100 and
  88)
• Identical closeness centrality (100)

46
Cluster Analysis Structural Equivalence

• The degree of structural equivalence
• Degree to which two actors have the same profile
  of relations to all other actors in the group.
• The degree is measured using the Pearson
  Correlation (r). Correlation is a technique for
  investigating the relationship between two
  variables.
• Person correlation ranges from 1,00 to 1,00.

47
Cluster Analysis Pearson Correlation (r)

• The Pearson correlation (r) is used to calculate
  each similarity index.
• In the bank example, the Person correlation
  indices is calculated as follow
• Bank Group has n6. Loan Manager is X
  1,0,1,1,1,1 and Profile Manager is
  Y1,0,0,1,1,1.

?
48
Cluster Analysis - Bank Example

• The similarity or distance matrix for all
  pair of actors.The Pearson correlation (r) is
  used to calculate each similarity index
• Taking the score in each cluster that is closest
  to some other cluster, the similarity is
  recalculated and the next most similar pair is
  joined.
• The pair most similar is Loan Manager and
  Profiler Manager. The calculated similarity is
  partial positive (0,6325).

49
Cluster Analysis The New Social Graph
50
Cluster Analysis The New centrality analysis
SIRA-AM
51
Assignment Model Similarity Analysis

• Similarity Analysis examines the correlation
  between two groups.
• The Cluster analysis is a way to grouping roles
  into sub-group. The roles are analyzed using two
  techniques
• The Centrality Correlation
• The first correlation is based on centrality
  measures
• The Similarity Correlation
• The similarity matrix indicates the extend to
  which the sub-group have the same profile of
  relations to the components.

SIRA-AM
52
Similarity Analysis Centrality Correlation

• The degree is measured using by computing the
  difference between the centrality scores of the
  most central point and those of all other point.
• Centrality Bank and Structure-in-5

53
Similarity Analysis Similarity Correlation
Matrix of correlation based on In-degree
(receiving relations)
Matrix of correlation based on Out-degree
(sending relations)
54
Similarity Analysis Correlation Matrix

• Bank graph
  Structure-in-5 graph

strong () or partial () positive correlation,
strong (--) or partial (-) negative correlation
SIRA-AM
55
Assignment Model Group and Architecture

• Bank graph
  Structure-in-5 graph

strong () or partial () positive correlation,
strong (--) or partial (-) negative correlation
SIRA
SIRA-AM
56
The Architectural Configuration
Index
Architectural Mapping
Assignment Model
Architectural Configuration
Sequence
SIRA
57
Architectural Mapping
58
The Bank Architectural Configuration
Index
SIRA
59
Final Considerations - Contributions
Index

• Narrowing the gap among requirements gtlt
  architectures
• Using same concepts for requirements and
  architectures
• Description in i framework
• Organizational concepts
• Mapping requirements into architecture and
  maintaining consistency of interactions
• Refine requirement and derive architecture into a
  systematic process

60
Final Considerations Future Works
Index

• Several Aspects of SIRA Framework requires
  further works
• Validation in a broad range of applications
• Definition of mechanism to deal with norms and
  conflict resolution in the organizational model
• Definition of guidelines to identify roles in the
  problem domain
• Definition of the process to support the
  development of SIRA models
• Tools to support the SIRA Process
• Architectural Catalogue To include social graph
  catalogue

61
Publications (2002 2003)
Index

• Bastos, L.R.D. and Castro, J.F.B.(2002) An
  Event Based Layered Architecture for Bank
  Systems. V Workshop Iberoamericana de
  Ingenieria de Requisitos y Ambientes de Software
  - IDEAS2002.
• Bastos, L.R.D. and Castro, J.F.B.(2002)
  Aplicação da Arquitetura com Modelo de Controle
  Baseado em Eventos no Banco do Brasil S.A. XVI
  Brazilian Symposium on Software Engineering
  SBES2002, p.207-221.
• Bastos, L.R.D. and Castro, J.F.B.(2003)
  Integrating Organizational Requirements and
  Socio-Intentional Architectural Styles. Second
  International Workshop From SofTware Requirements
  to Architectures (STRAW03), 2003. p.114 121.
• Bastos, L.R.D. and Castro, J.F.B.(2003)
  Integration between Organizational Requirements
  and Architecture. WER03 - VI Workshop em
  Engenharia de Requisitos.

SIRA
62
Publications (2004 2005)
Index

• Bastos, L.R.D. and Castro, J.F.B. (2004)
  Systematic Integration between Requirements and
  Architecture. Third International Workshop on
  Software Engineering for Large-Scale Multi-Agent
  Systems SELMAS'04.
• Bastos, L.R.D. and Castro, J.F.B. (2004)
  Enhancing Requirements to derive Multi-Agent
  Architectures. WER04 - VII Workshop em
  Engenharia de Requisitos.
• Bastos, L.R.D. and Castro, J.F.B. (2005)
  Systematic Integration between Requirements and
  Architecture. LNCS 3390 Software Engineering
  for Multi-Agent Systems III, pp. 85-103.R.Choren
  et all. (Eds.), Springer-Verlag, 2005.
• Bastos, L.R.D. and Castro, J.F.B. (2005) From
  Requirements to Multi-Agent Architecture based on
  Organisational Concepts. 4th International
  Workshop on Software Engineering for Large-Scale
  Multi-Agent Systems SELMAS'05.
• Bastos, L. R.D. e Castro, J. F.B. (2005)
  Organizational Model to Derive Multi-Agent
  Architecture from Requirements. CAISE05 Forum.

SIRA