1. درس مهندسی نیازمندی ها استاد دکتر عبداله زاده دانشجو خیرالنسا مرچانت Dealing with NFR : Three Experimental Studies of a Process-Oriented Approach

2. Introduction
In past, relatively little attention has been paid to the process of systematically dealing with NFR and developers have relied mostly on their own intuition in an ad-hoc way.
To remedy the problems inherent in ad-hoc development, a framework has been developed to deal with non-functional requirements.
The purpose of this paper is to give an initial evaluation of a recently proposed framework for dealing with non-functional requirements, by way of three studies of small portions of three information systems such as accuracy, security and performance.
This paper attempts to evaluate the extent to which the frameworks’ objectives are met, namely representing NFR-specific requirements, considering design trade-off, relating design decisions to NFRs, justifying the decisions and assisting defects detection.

3. Three studies Credit Card Health Insurance Taxation User-friendliness
Accuracy
Ranging from commercial to governmental
Considerable variation in domain charachteristics
Performance
Security

4. Process Vs. Product
Quality of a product depends largely on the quality of the process that leads form high level NFRs to the product
Complementary to the traditional product approach whose emphasis lies in product evaluation , usually involving metrics
A little discussion about process oriented trend in QA and its reasons

5. NFR Framework
Allows treating NFRs as potentially conflicting or synergic goals to achieve
Considering development alternatives which could meet the stated NFRs
Examining design tradeoffs
Relating design decision to NFRs
Justifying the decisions in relation to the needs of the intended application domain
Assisting defect detection

6. Goal Graph Structure Used for record and structure NFRs
Design alternatives
Decisions
rationale

7. Goal Graph Structure for Secure Document
Security
User Friendliness U U
Accuracy
Availability
Confidentiality U U U
External Confidentiality
Identification
Internal Confidentiality U U S
Authentication
IntConf
(Small Accounts)
Access Authorization U U
IntConf
(large Accounts) U U
Vital Few Trivial Many S U S U
Biometric
Password
IntConf
Card Key

8. Sort Hierarchy NFR Sort User Friendliness Cost Security Performance
Operating Cost
Development Cost
Time
Availability
Confidentiality
Space
Integrity
Throughput
Response
Time
Accuracy
Completeness
Main
Memory
Secondary
Storage
Internal Consistency
External Consistency

9. Where Specific NFRs come from?
Development knowledge about specific NFRs are to be taken from the literature and industrial experience and captured as methods, which are then presented for reuse to help the developers generate new goals and links

10. Methodology for Using NFR Framework
Knowledge acquisition
Acquisition of knowledge specific to NFRs
Academic
industrial
Acquisition of domain knowledge
organization
Application of the NFR-Framework
Identification of NFR-related concepts
Identification of important NFR goals
Identification of development techniques
Identification of design rationale
Linking NFR-related concepts
Process, tools, output

11. Linking NFR-related Concepts
Refining, clarifying and relating goals
Identification of critical NFR goals
Providing design rationale
Assessing goal achievement

12. Refining, clarifying and relating goals
Relating development techniques to NFR goals
Identifying conflict and synergy
Clarifying the meaning of goals
Individually
Associatively
Identifying factors underlying correlations
Development techniques - design and implementation

13. Identification of critical NFR goals
Identifying what development techniques were repeatedly emphasized
Identifying critical goals and critical dominant parts of the work load

14. Providing design rationale
Locating applicable design rationale from either the source document or workload description
Providing some design rationale from the basis of development tradeoffs present in goal graph structure under construction
Design rationales are about choosing particular techniques

15. Internal Evaluation
When developers made aware of quality concerns, that by itself helps improve the overall software quality
When conflicts and synergy among NFR goals were explicitly described, it is possible to consider design tradeoffs in selecting among alternatives
When competitive alternatives exist, expressing critical goals and the effect of each design decision helps resolving conflicts and record design rationale
Relating design rationale back to source NFRs which could improve traceability

16. Internal Evaluation (Cont.)
Detecting faults
Ambiguity of goals
Distinguishing goals into three types for detecting omissions
Antagonistic correlation rules help detecting conflicts
Detection of redundancies
Synergic correlation helps in detecting opportunities

17. Negative Findings Need for new decomposition methods Design rationale
Qualitative approach
Scalability of goal graph

18. Experts Evaluation Framework would be helpful for developers
Improvements in naming and presentation are needed to increase understandability
Lack of consultation with domain people during the study left gaps in domain knowledge
Applicability to broader domains
Training costs and payoffs

19. Framework Findings Goal graph structures understandability
Framework emphases
Formality
Process oriented approach
Tradeoffs
Determining main requirements
Clarify requirement

20. Application Domain Findings
Domain knowledge and proportionality
Lack of contact with domain people
Usage of framework
Accuracy predominated security in spite of what NFR team thought

21. Conclusion
NFR framework helps in presenting and using large numbers of NFRs
NFR representation helps in considering design alternatives and their tradeoffs
It is not clear that significantly larger studies could be handled by NFR-assistant tool
It is important to find a cost effective way for training users work with framework

22. Reference
Chung, L., Nixon, B.: Dealing with Non-Functional Requirements :Three Experimental Studies of a Process-Oriented Approach. In: Proc. of ICSE’95, pp. 25–37. ACM Press (1995)