Intro to documenting requirements with models

Question 1

Model-based requirements specification

Answer 1

• Requirements are described as a problem-oriented model of the system to be built
• Architecture and design information is omitted
• Mostly graphically represented
• For functional requirements
  
  • Quality requirements and constraints are mostly
    specified in natural language
  • with UML

Question 2

use case diagrams

Answer 2

express the expectations of the stakeholders

Question 3

We can use a use case diagram to answer the following questions:

Answer 3

• What is being described? (The system)
• Who interacts with the system? (The actors)
• What can the actors do? (The use cases)

Question 4

use case

Answer 4

• Describes functionality expected from the system under development
• The set of all use cases describes the functionality that a system shall provide

Question 5

actors

Answer 5

• Actors interact with the system
  
  • by using use cases, i.e., the actors initiate the execution of use cases
  • by being used by use cases, i.e., the actors provide functionality for the execution of use cases.
  • Actors represent roles that users adopt
    
    • Specific users can have multiple roles simultaneously
  • Actors are not part of the system, i.e., they are outside of the
    system boundaries

Question 6

actor ii

Answer 6

• Human
  
  • E.g., Student, Professo
• Non-human
  
  • E.g., E-Mail Server
• Primary: receives main benefit from execution of the use case
• Secondary: receives no direct benefit
• Active: initiates the execution of the use case
• Passive: provides functionality for the execution of the use case

Question 7

Relationships between Use Cases and Actors

Answer 7

• Actors are connected with use cases via solid lines (associations)
• Every actor must communicate with at least one use case
• An association is always binary
• Multiplicities may be specified