ステーキホルダーの非機能要求を充足するための振る舞い仕様の段階的改訂法

1. ステーキホルダーの非機能要求を充足するための振る舞い仕様の段階的改訂法ステーキホルダーの非機能要求を充足するための振る舞い仕様の段階的改訂法 海谷 治彦 信州大学 2001年9月 宇和島にて

2. Outline • Goal of our Work. • Constructing a Requirements Elicitation Method. • Basic idea for our Goal. • Sub goals and their solutions. • Notation for evaluating spec. by multiple stakeholders. • Method for causing a chain of spec. change. • Method for merging several chains. • Example

3. Goal of our Work • Constructing a Requirements Elicitation (RE) Method. • Domain of the method. • Multiple Stakehodlders (SH) • Motivation to introduce Info. Tech. (IT) • Existence of the Current Task (CT) • Interactive System: WBS, UIS • A case without a computer system support. • Another case with a computer system support.

4. Basic Idea • Stepwise Introduction of IT(=Change) to CT. • SH’s Evaluation of the Change. • Such Eval. triggers the other Changes. • Reasonable Trade-off among the SH’s. • Shared Criteria for SHs to Change Evaluation. • Concurrent RE for Efficiency.

5. Sub goals of our Work • Develop a notationforSH’s Evaluation. • Develop a procedurefor causing a chain of IT introduction. • IT introduction => CT change => SH eval. change = >Specification refinement • Develop a procedure for merging such chains safely for concurrent RE.

6. Notation of Spec. • Sequence Diagram for representing Requirements Spec. • Easy to capture the interaction among the SHs. • Easy to Understand ordinary people. • Behavioral Aspect is important for interactive system.

7. NFR for shared Criteria • Non-Functional Requirements (NFR) • shared by stakeholders to evaluate a change of CT. • Type of NFR • Performance: Time and Space • Cost. • User-Friendliness. • Security: Confidentiality, Integrity, Availability. • And additional criteria. • Ease: delegation of a task to systems.

8. Stakeholders • Have a stake in the change being considered, those who stand to gain from it, and to lose. • Categories of SH in computer systems. • Those who are responsible for its design and development. • ... for its sales or for its purchase. • ... for its introduction and maintenance. • Those who have an interest in its use.

9. A notation for SH’s EvaluationEvaluation Table Quantitative Evaluation can be accomplished!

10. Chain of Requirements Change (CRC) • Write an Initial Specification of CT. • A SH states his advantages and disadvantages of the spec. • Change the spec. so as to eliminate disadvantages. • Other SHs state them in the same way. • Change the spec. in the same way. • Back to the Step2.

11. Current Task Overview of our RE Proc. in Chain Creation Other Stakeholders A Stakeholder Initial Spec. Eval. Table - cause Eval. Table Refined Spec. - + Eval. Table + - + + -

12. Example of a part of Chain Op. have disadv. in X Spec. X Elim. the disadv. Spec. Y Evaluation is quantitatively up.

13. Merge Chains for Concurrent RE • Multiple SHs: Concurrent RE is efficient. • We should safely merge the results of RE. • Precondition of our merge procedure. • Sequence Diagram: notation for spec. • The inputs are two chains. • Two chains share the same initial Spec. • Postcondition • Merged Spec. and Evaluation Table.

14. Two Step of Merge Method • Horizontal Check • Consistency in the topology among the objects. • Collaboration Diagram • Vertical Check • Consistency in causal relations. • Retrying by shortening a chain. • if inconsistency is found. • Evaluation score is of course decreased.

15. Overview of Merge Proc. initial spec. Chain of A refined spec. A0 refined spec. B0 Chain of B eval. tablea eval. table I refined spec. A1 refined spec. B1 Inputs eval. table eval. table A B refined spec. A refined spec. B generate diagram IB IA eval. table eval. table Hori. Check use the diagram for the check Vert. Check Collaboration diagram Outputs refined Spec. A+B eval. table A+B

16. Horizontal Check • Checking the inconsistency of relationships among the objects. • Convert sequence diagram to collaboration diagram. • No relationship in an initial diagrams is changed in the different way in each refined diagrams.

17. Example of Horizontal Check Contributor Initial Spec. legend: paper ack. of abst. CFP abst. ack. of abst. cut path. add path. Chair refinement A, B, C, D abst. list Reviewer Candidate refinement X, Y Committee Spec. D Spec. Y Contributor Contributor Chair Chair abst. list’ Committee Committee

18. Vertical Check • Checking the consistency in causal relations among the messages. • Not all messages need not be checked, check the following kind of messages. • Messages in both initial spec. and spec. A, but modified in spec. B. • Messages only in spec. B. Check this by replacing A and B. Init. Spec RE chain RE chain Spec. A Spec. B

19. Example of Vertical Check Contributor Initial Spec. legend: paper ack. of abst. CFP abst. ack. of abst. cut path. add path. Chair refinement A, B, C, D abst. list Reviewer Candidate refinement X, Y Committee Spec. D Spec. Y Contributor Contributor Only check the inconsistency in Y Chair Chair abst. list’ Committee Committee

20. Conclusion • Stepwise refine the Spec. • Quantitative Evaluation of each step based on the stakeholders’ intention. • Enable the Concurrent Elicitation by merge step.

21. Q & A • 何故，横チェックを先にやるか？ • 横チェックの方が楽なため。 • 横チェックを基に縦チェックをする個所を絞れる。 • シーケンス図にはSHでないものも出てくるがどうするか？ • シーケンス図のオブジェクトと評価表の列側は一応別個と考え，オブジェクトはSHに限らず自由に選んでよいことにする。 • 仕様の変化とステーキホルダの評価の関係が曖昧となるが，そもそも主観的評価に基づくので問題ない。

22. Future Work • Prioritize stakeholders and/or NFR for evaluation. • Quantitative comparison for selecting the reasonable chain of specification change. • Building an Estimation Method: estimating the introducing effort. • Applying a realistic problem and/or development.

23. Appendix

24. Time Keeper Contributer Gathering System Fiter System Chair Committee Reviewer Spec. D * Send CFP * Send abst Ack. Write abst. * Request reviewer Gather abst. Gather papers *take on reviewer Write paper * Send paper Ack. Submission Limit * Send paper list *back rev. candidates

25. Time Keeper Contributer Format Checker Gathering System2 Chair Committee Reviewer Spec. Y * Send CFP * Send abst Ack. Gather abst. Write abst. Gather papers Write paper * Send paper Fmt nack. Ack. Submission Limit * Send paper list * Request reviewer *take on reviewer *back rev. candidates