Towards a Model-based COTS-Aware Requirements Engineering Approach

1. Towards a Model-based COTS-Aware Requirements Engineering Approach Lawrence Chung and Kendra Cooper MBRE ‘01

2. Today... • Introduction (Why CARE?) • Our Preliminary CARE Approach • Current State of the CARE Research • Conclusions • Future Work

3. Introduction - Why CARE? • Standard COTS Approach (e.g. RUP) • Develop Requirements • Develop Architecture • Develop Detailed Design and Consider COTS • Here, COTS Components Must Meet Functional & Non-functional Requirements AND Fit With the Architecture • Detailed Design Phase Is Too Late • Difficult to Find COTS Components  Consider COTS in the Requirements Phase

4. An Ideal CARE Approach • Customer “Satisficing” • Flexibility of Customer Requirements • Matching and Selecting COTS Components • Goal-oriented • Method (or Process) Based • Knowledge-Based • Should Consider the Impact on Entire SDLC

5. Initial System Concept Agents Define System Agents Baselined System Req. (with COTS) Updated Foreign Goals 1 Define System Goals 2 Define Software Requirements Updated Foreign Reqs. Initial Goals Define System Requirements Foreign Goals 4 3 Foreign Requirements Define Hardware Requirements 5 Corrections to System Requirements Define Interface Requirements Baselined System Goals (with COTS) 6 Corrections to Refined Requirements RE RE RE RE RE RE Our Preliminary CARE Approach IDEF0

6. Our Preliminary CARE Approach • Methodology • Select Information System Example • Digital Library System • Develop a System Level Specification • Use a Middle Out Strategy • Start With Step “Define System Requirements” * • Use Small Examples From the Library System • Define and Validate the Process • Define the Knowledge-Base (repository) • Use i*, NFR, and IDEF0 notations * Subsequent Steps: Define System Goals, Define System Agents Define Software, Interface, and Hardware Requirements

7. Validate System High Quality … Create Baselined System Goals with COTS Create System Within Budget Requirements Engineer Within Schedule Create Baselined Software Reqs. with COTS Create Baselined System Reqs with COTS … Customer … Create System Planning Artifacts Create System Goals Create Software Requirements Create System Requirements Strategic Rational and Dependency Models for CARE Create System Product Artifacts Legend Decomposition Dependency Preliminary CARE Approach i*

8. Create Baselined System Reqs. (with COTS) System Requirementsss Component Repository Component Repository Component Repository Component Repository Create Baselined System Requirements (with COTS) Select Candidate Reqs. Elicit System Reqs. Analyze System Reqs. Correct System Reqs. Define COTS Reqs. Verify System Reqs. Baseline System Reqs. Trace System Reqs. Detailed Search of Repository Select Component Detailed Match of Components Prelim. Match of Components Request Change to Component Request Change to Req. Maintain Components Prelim. Search of Repository Legend Decomposition Preliminary CARE Approach i*

9. Preliminary CARE Approach • Example (Digital Library System) • Define System Goals • Elicit Initial System Goal • Digital Library Should Comply With Current Standards • Refine System Goal • Digital Library Should Comply With ANSI/NISO Z39.50-1995 (version 3) • Baseline System Goals

10. Preliminary CARE Approach • Define System Requirements (with COTS) • Elicit Initial System Requirements • Select Candidate System Requirements • Preliminary Search, Preliminary Match • Detailed Search, Detailed Match • MatchBlue Angel, Metastar Gateway & Server Components Z39.50 version 3 • Select Component • Correct System Requirements • Baseline System Requirements

11. Current State of CARE • Addresses COTS at “Define System Goals” Step • Validation Uses Another Example From the Digital Library System • The Example Is More complex: Conflicting Set of Functional and Non-functional Goals • Configurability of CHI, Performance, Cost,...

12. SoftgoalN … … Component 1 Component n System Under Development (Native Goals, Native Requirements) Component Repository (Foreign Goals, Foreign Requirements) GoalN GoalN Component 2 GoalsF GoalsF GoalsF System RequirementsF System RequirementsF System RequirementsF Legend Agent Mapping Native Goals to Foreign Goals Mapping Native System Requirements to Foreign System Requirements Hardware RequirementN Interface RequirementN System RequirementN System RequirementN System RequirementN Software RequirementN Mapping Native Goals and Requirements to Foreign Goals and Requirements Current State of CARE

13. System Administrators, Librarians, Borrowers (novice) System Administrators, Librarians, Borrowers (expert) Librarians, Borrowers, System Administrators, Managers of Librarians and System Administrators - - + - Librarians, Borrowers, System Administrators, Managers of Librarians and System Administrators Librarians, Borrowers, System Administrators, Managers of Librarians and System Administrators - - - Procurement Office - - Librarians, Borrowers, System Administrators, Managers of Librarians and System Administrators 2c 3a 2b 5a 4a 2a 2d Legend Goal Agent Relationship between Agents and Goals/Softgoals + Positive Relationship Softgoal Relationship between Goals/Softgoals - Negative Relationship Relationships Among Native Goals and Softgoals Current State of CARE

14. Conclusions • Use of COTS Components is a Complex Problem • Requires a Systematic Approach • Our Methodology Seems to be Working • Preliminary CARE Approach is Serving as a Foundation • CARE Approach is Being Elaborated, Refined, and Validated

15. Future Work • Continue the Definition and Validation of the CARE Approach • Formal Representation and Reasoning of Goal Conflicts • Build Knowledge-Base (repository) • Trade-off Analysis for Possible Configurations • Investigate the Impact of CARE on System Architecture, Development Costs, Maintenance,...