1. Requirements validation through viewpoint resolution By Julio Cesar Sampaio do Prado Leite Peter A. Freeman

2. Overview  Origins  Software engineering, specifically requirement engineering  System engineering methods SADT and CORE  Purpose  Provides an early validation of requirements for complex systems  Goal  Help with the elicitation process for requirements by the comparison of different views

3. Main phases 1. Define universe of discourse a) Identify possible actors b) Selection of actors 2. Construction of views a) Analyse perspectives and hierarchies b) Solve conflicts internally 3. Analysis of viewpoints a) Produce rule set b) Identify rule pairs i. Most problaby rules pairs ii. Rules with no pair c) Identify discrepancies

4. Related literature

6. Process-Deliverable Diagram – part 1

7. Process-Deliverable Diagram – part 2

8. Example 1. Define universe of discourse (Renting DVDs at Blockbuster) a) Identify possible actors (Staff,people that rent DVDs and DVD supplier) b) Selection of actors (Staff and people that rent DVDs) 2. Construction of views a) Analyse perspectvies and hierarchies (Process, data and actor) b) Solve conflicts internally (Availability of DVD in process but not in data) i. Result: actors’ final view, written in VWPL 3. Analysis of viewpoints a) Produce rule set (Produce rule set from actors`s final view for comparison) b) Identify rule pairs i. Most problaby rules pairs ii. Rules with no pair c) Identify discrepancies

9. Example View A: ((DVD =category =name =reg-number) View B: ((DVD =name =reg-type) (staff = name) The discrepancies identified by the static analyzer are:  Attribute category used in entity DVD in view A is missing in View B;  Attribute reg-number used in entity DVD in view A is called reg-type in View B;  The entity staff in view B is missing in view A. Final result: final viewpoint from the two actors combined written in VWPL, which can be used as a software requirement.