Lecture_04 Flashcards
Modeling Goals
What is the purpose of goal-oriented requirements modeling?
It helps stakeholders understand their needs by focusing on why a system is needed, not just what it does.
Why is goal modeling important in modern systems?
Many modern systems are socio-technical, involving complex relationships between people, software, and organizations.
Give an example of how goal modeling can be applied in real life.
Kids Help Phone (KHP): A non-profit counseling service wanted to ensure confidentiality and quality of service when moving online.
-Air Traffic Control System: Ensuring safety and timely warnings for airspace infringements.
What is the difference between requirements and goals?
Goals describe what users want to achieve (high-level and abstract).
Requirements describe how the system fulfills those goals (more detailed and specific).
What is i* (iStar) in goal modeling?
iStar is a framework for goal modeling that represents actors, goals, dependencies, and relationships.
What are the two main models in iStar?
Strategic Dependency (SD) model (focuses on actor dependencies).
Strategic Rationale (SR) model (focuses on goals and reasoning).
What are the four types of dependencies in the SD model?
Goal Dependency: “Achieve this goal, I don’t care how.”
Task Dependency: “Achieve this task in a specific way.”
Resource Dependency: “Provide this item.”
Quality Dependency: “Ensure this quality.”
What is the difference between SD and SR models?
SD model: Shows relationships between actors and their dependencies.
SR model: Explores the reasoning, alternative goals, and trade-offs in achieving objectives.
What is the role of actors in the SD model?
Actors represent stakeholders, roles, or systems that have goals, dependencies, and tasks.
What is the purpose of goal dependency in an SD model?
It represents an actor relying on another actor to achieve a goal, without specifying how.
How does the task dependency differ from the goal dependency?
In task dependency, the dependent actor specifies how the task should be done.
What does a resource dependency represent?
It shows that one actor needs a specific resource from another actor (e.g., data, documents, or software).
How does quality dependency impact system design?
It ensures that a system meets non-functional requirements like security, privacy, or performance.
What does the SR model add beyond the SD model?
It includes goal refinement, alternative solutions, trade-offs, and quality considerations.
What is goal refinement in the SR model?
Breaking down high-level goals into smaller, achievable sub-goals using AND/OR refinements.
What are the two types of goal refinements in the SR model?
AND-refinement: The goal is achieved only if all sub-goals are fulfilled.
OR-refinement: The goal can be achieved by one of many possible alternatives.
What are contribution links in SR models?
They show how different tasks or goals affect qualities (positively or negatively).
What do the contribution labels (+, -, ++, –) mean?
Make (++): Strongly supports a quality.
Help (+): Positively influences a quality.
Hurt (-): Negatively impacts a quality.
Break (–): Strongly harms a quality.
Why is the SR model useful for decision-making?
It visualizes trade-offs, helping teams choose the best alternative based on quality considerations.
How can iStar be used in a bike rental system?
Goal: Allow users to rent bikes easily.
Dependencies: Payment system, maintenance staff, city regulations.
Quality goals: Security, usability, affordability.
How can iStar be applied in healthcare?
Goal: Improve patient satisfaction.
Dependencies: Doctors, nurses, hospital management.
Quality goals: Privacy, efficiency, accessibility.
What is an example of a trade-off in an online shopping system?
Goal: Improve user experience.
Positive Contribution: “Fast checkout process” helps usability.
Negative Contribution: “Fewer security steps” hurts security.
What are some popular iStar modeling tools?
CreativeLeaf (Chalmers University).
piStar (Web-based goal modeling tool).
jUCMNav (For GRL goal modeling).
What is CreativeLeaf, and why is it recommended?
It is a web-based tool for creating iStar goal models with an easy-to-use interface.
What is the best general-purpose tool for drawing iStar models?
Draw.io or Miro (if specialized iStar tools are not available).
What is intentionality in goal modeling?
It represents why stakeholders want certain goals, not just what they do.
Why is early consideration of qualities important?
Qualities like security, performance, and usability should be considered before system design, not afterward.
What is the space of requirements?
It refers to all possible requirements that could achieve a goal, from which a subset is chosen.
What are viewpoints in goal modeling?
Different stakeholders may have different priorities, and goal models help balance trade-offs.
Why does iStar emphasize contributions and trade-offs?
Because different solutions impact system qualities differently, and goal models help optimize choices.
