Specialization in i* Strategic
Rationale Diagrams
Outline
• Motivation and research question
• Antecedents
• Proposal
 Notion of correctness
 Specialization operations

•...
Motivation
Two types of i* diagrams
Customer

Travel
Agency

Easily Bought

SD diagrams
Travel
Agency

Customer
Buy Travel...
Motivation
Our focus: specialization in i* through is-a
Customer

Easily Bought

Travel
Agency

is-a

Family

The is-a ass...
Motivation

The ultimate effect of is-a is not clear:
• The i* guide does not define it
• i* modelers use it intuitively (...
Motivation

• How are the IEs belonging to Customer
inherited in Family?
• What manipulations are valid over them?
 E.g.,...
Research Question
Given an actor specialization relationship
declared at the SD level, what modeling
operations can be def...
Strategy
Formulate an answer that aligns with:
• the general concept of specialization in
the conceptual modeling communit...
Antecedents: conceptual modeling
Analysis using Meyer’s Taxomania rule: “Every heir
must introduce a feature, redeclare an...
Reported uses

Regularly used but
RQ not answered

10
Community perception: a survey
21 valid responses (July-Sept. 2010; 4th i* wks.)
• 57% use sometimes, often or very often
...
As a result…
From the three different possibilities:
• Extension: a new IE or dependency,
related somehow to inherited
ele...
Notion of correctness
• Algebraic formalization: see paper
 Some simplifications made

b

is-a
a

• Actor specialization ...
Notion of correctness
• IE correctness:
 ie not decomposed: given by user
 ie decomposed: see decomposition
task-decomp...
Definition of operations
• The paper introduces 5 different operations (2
for extension, 3 for refinement)
• For each oper...
Extension operations
• OP1: IE extension with decomposition link:
TA
is-a
UTA
Name a Price

Travels
Contracted
Increased

...
Extension operations
• OP2: Addition of new main IEs
Services
Provider
is-a

Profit Increased

Travel
Services
Provider
Cu...
Refinement operations
• OP3: IE refinement
 the implication given by correctness definition needs
to be preserved

18
Refinement operations
• OP4: contribution link refinement
 always keeping the “polarity” of the value
TA
Assistance
Provi...
Refinement operations
• OP5: dependency refinement
 either dependum (IE) or strength (not in the paper!!)
TA

Customer

N...
Conclusions
Research questions answered:
What modeling operations can be defined at
the SR level? EXTENSION & REFINEMENT
•...
Future work
• Consider also redefinition
• Ontological meaning for specialization
• Apply same strategy for other types of...
Hope you
liked it!
Upcoming SlideShare
Loading in …5
×

Specialization in i* Strategic Rationale Diagrams

1,179 views

Published on

The specialization relationship is offered by the i* modeling language through the is-a construct that applies over actors (a subactor is-a superactor). Although the overall meaning of this construct is highly intuitive, its semantics when it comes to the fine-grained level of strategic rationale (SR) diagrams is not defined, hampering seriously its appropriate use. In this paper we provide a formal definition of the specialization relationship at the level of i* SR diagrams. We root our proposal over existing work in conceptual modeling in general, and object-orientation in particular. Also, we use the results of a survey conducted in the i* community that provides some hints about what i* modelers expect from specialization. As a consequence of this twofold analysis, we identify, define and specify two specialization operations, extension and refinement, that can be applied over SR diagrams. Correctness conditions for them are also clearly stated. The result of our work is a formal proposal of specialization for i* that allows its use in a well-defined manner.

Published in: Technology, Business
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
1,179
On SlideShare
0
From Embeds
0
Number of Embeds
5
Actions
Shares
0
Downloads
3
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Specialization in i* Strategic Rationale Diagrams

  1. 1. Specialization in i* Strategic Rationale Diagrams
  2. 2. Outline • Motivation and research question • Antecedents • Proposal  Notion of correctness  Specialization operations • Conclusions and related work 2
  3. 3. Motivation Two types of i* diagrams Customer Travel Agency Easily Bought SD diagrams Travel Agency Customer Buy Travel SR diagrams Easily Bought Name a Price Travels Bought Easily They need to be synchronized 3
  4. 4. Motivation Our focus: specialization in i* through is-a Customer Easily Bought Travel Agency is-a Family The is-a association represents a generalization, with an actor being a specialized case of another actor (ref. The i* Guide) 4
  5. 5. Motivation The ultimate effect of is-a is not clear: • The i* guide does not define it • i* modelers use it intuitively (and sometimes inconsistently) 5
  6. 6. Motivation • How are the IEs belonging to Customer inherited in Family? • What manipulations are valid over them?  E.g., may Buy Travel have additional subtasks? • Do Customer dependencies apply to Family? 6
  7. 7. Research Question Given an actor specialization relationship declared at the SD level, what modeling operations can be defined at the SR level? • What is the relevant background to make this decision? • What are the effects of these operations? • What are the correctness conditions to be fulfilled for their application? 7
  8. 8. Strategy Formulate an answer that aligns with: • the general concept of specialization in the conceptual modeling community • the reported uses made by i* researchers • the preferences gathered empirically from the community 8
  9. 9. Antecedents: conceptual modeling Analysis using Meyer’s Taxomania rule: “Every heir must introduce a feature, redeclare an inherited feature, or add an invariant clause”. Area Knowledge Representation Approach Strict Defeasible New feature Add Invariant Redeclare feature New Attributes No No No Attribute Cancellation Simula 67 No Smalltalk-80, Delphi, C++, C#, Java OO Languages Visual Basic New Properties & Methods Conceptual Modeling UML Borgida & Mylopoulos Overrides for methods Simulation for properties accessing via methods Overrides and Shadows for properties and methods Adding invariants Eiffel Semantic data models Simulation accessing properties via methods New Attributes & Methods Renaming and Redefinition for routines and procedures using contracts No No No No Attributes No 9
  10. 10. Reported uses Regularly used but RQ not answered 10
  11. 11. Community perception: a survey 21 valid responses (July-Sept. 2010; 4th i* wks.) • 57% use sometimes, often or very often is-a links in their i* models • 84% have doubts about its usage • 85%-90% allow for addition of elements (dependencies / IEs) • 14%-38% allow for modification of elements • 5%-10% do not allow for removals of elements 11
  12. 12. As a result… From the three different possibilities: • Extension: a new IE or dependency, related somehow to inherited elements, is added to the subactor. • Redefinition: an IE or dependency that exists in the superactor is changed in the subactor. • Refinement: the semantics of an inherited IE or dependency is made more specific. 12
  13. 13. Notion of correctness • Algebraic formalization: see paper  Some simplifications made b is-a a • Actor specialization correctness: sat(a, M) sat(b, M) • Actor correctness: sat(ie, M) = ie mainIEs(a): sat(ie, M) 13
  14. 14. Notion of correctness • IE correctness:  ie not decomposed: given by user  ie decomposed: see decomposition task-decomposition: sat(ie, M) sat(iesub, M) means-end: sat(iemeans, M) sat(ie, M)  ie with contributions (softgoal): Horkoff&Yu’s rules  ie with outgoing dependencies: sat(ie, M) sat(iedep, M) 14
  15. 15. Definition of operations • The paper introduces 5 different operations (2 for extension, 3 for refinement) • For each operation:  Definition:  signature  precondition  postcondition (effects)  Theorem: actor specialization correctness is kept  always by induction • I’m not going to do that here!! 15
  16. 16. Extension operations • OP1: IE extension with decomposition link: TA is-a UTA Name a Price Travels Contracted Increased Customers Attracted is-a Sell Travels Assistence Provided Travels Contracted Increased Book Travel Help Get Travels Search Trip by Conference Attractive Products OR Search Trip by Destination Name a Price Good Quality-Price Rate FTA Good Quality-Price Rate Help OR Many Kind of Travels Offered Family Facilities Offered Provide Child Discounts Many Kind of Travels Offered Help Provide Familiar Destinations Remark: please notice the graphical convention 16
  17. 17. Extension operations • OP2: Addition of new main IEs Services Provider is-a Profit Increased Travel Services Provider Customer data sold to 3rd Many Transactions Processed Costs Reduced Hurt Help Travel Services Provided Hurt List Offerings Privacy Kept Encrypt Data Contract Travels Encrypt Data Help 17
  18. 18. Refinement operations • OP3: IE refinement  the implication given by correctness definition needs to be preserved 18
  19. 19. Refinement operations • OP4: contribution link refinement  always keeping the “polarity” of the value TA Assistance Provided Travels Contracted Easily Asynchronous Support is-a Synchronous Support FTA Customer Help Assistance Obtained is-a Help Travels Bought Easily Family Assistance Provided Synchronous Support Make Travels Contracted Easily Provide Hotline [Telephone] Assistance Obtained Make Travels Bought Easily 19
  20. 20. Refinement operations • OP5: dependency refinement  either dependum (IE) or strength (not in the paper!!) TA Customer Name a Price Book Travel Travel Offerings Travel Offerings Customer Info is-a Contract Travel is-a Research er UTA Name a Price Book Travel Conference [Travel Offerings] Unversity&[Cust omer Info] X Conference [Travel Offerings] Contract Travel 20
  21. 21. Conclusions Research questions answered: What modeling operations can be defined at the SR level? EXTENSION & REFINEMENT • What is the relevant background to make this decision? SOTA & SURVEY • What are the effects? FORMAL DEFINITION • What are the correctness conditions to be fulfilled for their application? SATISFACTION NOTION 21
  22. 22. Future work • Consider also redefinition • Ontological meaning for specialization • Apply same strategy for other types of actor links 22
  23. 23. Hope you liked it!

×