1. Goal-Oriented Requirements Engineering (GORE) “Goal-oriented requirements engineering is concerned with the use of goals for eliciting, elaborating, structuring, specifying, analyzing, negotiating, documenting, and modifying requirements.” (van Lamsweerde 2001) Goals can be viewed as the earliest/highest-level requirements artefacts Can form the organizing locus for all subsequent RE activities

2. GORE: Key issues Goal modeling Obtaining downstream artefacts from goal models Maintaining consistency of goal models Incorporating NFRs into goal models Using goals as requirements rationale

3. A goal graph

4. KAOS: Outline KAOS: Knowledge Acquisition in autOmated Specification A comprehensive GORE framework Four models: –Goal model –Object model –Agent model –Operation model Constructs: –Graphical and a textual syntax –Defined using the real-time temporal logic

5. KAOS Ontology (1/3) Objects: Can be: entity (autonomous object), relationship (subordinate object), event (instantaneous object) Actions/Operations: –Input/output relations over objects –Operation application defines a state transition –Have pre-conditions, post-conditions and trigger conditions –Distinguish between: Domain pre-, post-conditions (domain specific, defined by the domain) Required pre-, post-condition (application-specific, required to achieve goals)

6. KAOS Ontology (2/3) Agents: Processors of operations –An agent performs an operation allocated to it –Monitors an object whose states can be observed by it –Controls an object whose states can be controlled by it Goals: Related to other goals via AND-refinement or OR-refinement links

7. KAOS Ontology (3/3) Requisite: A goal that can be formulated in terms of states controllable by an agent –Goals end up via a sequence of AND/OR refinements as requisites assigned to agents –Requisites are AND/OR operationalized by operations and objects (may require strengthening of pre-, post- and trigger conditions) –Alternative means of assignment of requisites to agents captured by responsibility links –Actual assignment of a requisite to an agent captured by performance link Requirement: Requisite assigned to a software agent Assumption: Requisite assigned to an environment agent Scenario: Sequence of operation applications by relevant agent (additional details ommitted)

8. KAOS: Operation/Agent Model

9. KAOS: Real-time Temporal Logic Assumes linear time

10. KAOS: Real-time Temporal Logic As opposed to branching time Now

11. KAOS: Real-time Temporal Logic (H, i)  |= P denotes that a history H (a linear time structure, assumed to be discrete), satisfies assertion P at time point i

12. KAOS: Real-time Temporal Logic Temporal operators

13. KAOS: Real-time Temporal Logic

15. KAOS: Goal Representation

17. KAOS: Agent/Relationship Representation