36 Questions
What is the primary concern of Requirements Engineering (RE)?
Understanding the real-world goals and constraints of software systems
What is the main difference between system requirements and software requirements?
System requirements include people and devices, while software requirements are limited to the software
According to Ross'77, what should requirements definition say?
Why a new system is needed, what features will satisfy the context, and how it is to be constructed
What is meant by 'system-to-be'?
The entire system, including the software, people, devices, and pre-existing software
What is the relationship between the software-to-be and the system-to-be?
The software-to-be is a component of the system-to-be
What triggers the need for requirements definition?
Problems raised by the current system and opportunities provided by new technologies
What is the primary goal of requirements engineering in the real-world problem?
To fully understand and define the real-world problem to be solved
What is the 'world' in the context of requirements engineering?
The real-world environment in which the problem arises
What is an example of a physical component in the 'world'?
A device
What is the primary concern of requirements engineering?
Understanding and defining the real-world problem
What is an example of a human component in the 'world'?
A staff member
What is the 'machine' in the context of requirements engineering?
The software solution to be developed
Why is it important to understand the context in which the problem arises?
To fully understand and define the real-world problem to be solved
What is the relationship between the 'world' and the 'machine' in requirements engineering?
The 'world' and the 'machine' are separate but related entities
What is the primary goal of identifying and analyzing the system-to-be's objectives?
To address analyzed deficiencies of the system-as-is
What is an example of a functional service in the airport train control system?
Computation of safe train accelerations
What is a difficulty in identifying and analyzing the system-to-be's objectives?
Acquiring domain knowledge
What is the purpose of evaluating alternative options in the WHY dimension?
To evaluate the implications of each option
What is a quality constraint that is considered in the WHAT dimension?
Performance
What is the relationship between the WHY and WHAT dimensions?
The WHY dimension identifies objectives, and the WHAT dimension defines features
What is a challenge in defining functional services in the WHAT dimension?
Specifying features precisely for understanding by all parties
What is the purpose of taking advantage of technology opportunities in the WHY dimension?
To address analyzed deficiencies of the system-as-is
What is the primary concern of Requirements Engineering (RE) in relation to the problem world and machine phenomena?
World phenomena, including shared ones
What is the system-as-is in the context of the problem world?
The system as it exists before the machine is built
What is the relationship between the world and the machine in terms of phenomena?
The world and the machine have their own phenomena while sharing others
What is the focus of software design in terms of phenomena?
Machine phenomena, including shared ones
What is the system in the context of the problem world?
A set of interacting components structuring the problem world
What is the primary goal of the machine in the context of the problem world?
To affect the problem world
What is the system-to-be in the context of the problem world?
The system as it should be when the machine operates
What is the nature of the relationship between the problem world and the machine?
The problem world and the machine are distinct but interacting
What is the primary goal of assigning responsibilities to system-to-be components in the WHO Dimension?
To define the software-environment boundary
What type of requirements are concerned with the estimation of train speed and position in the airport train control example?
Functional requirements
Which of the following is NOT a dimension of Requirements Engineering?
The HOW Dimension
What is the primary focus of the WHO Dimension in Requirements Engineering?
Assigning responsibilities to system components
What type of statements are used to describe the current state of the system in Requirements Engineering?
Descriptive statements
Which of the following is a target quality to avoid in Requirements Engineering?
Defects
Study Notes
Setting the Scene
- Requirements Engineering (RE) is concerned with understanding and defining a real-world problem, its context, and the desired machine's effect on the problem world.
The Problem World and the Machine Solution
- The problem world refers to the problematic part of the real world, consisting of human and physical components.
- The machine solution refers to the software and hardware to be developed and/or purchased to solve the problem.
The Problem World and the Machine Solution (continued)
- The world and the machine have their own phenomena, but share some others.
- RE is solely concerned with world phenomena, including shared ones.
System Versions
- There are two system versions: system-as-is (the current system) and system-to-be (the system as it should be when the machine operates).
RE: A Preliminary Definition
- RE is a coordinated set of activities for exploring, evaluating, documenting, consolidating, revising, and adapting the objectives, capabilities, qualities, constraints, and assumptions on a software-intensive system.
What Others Have Said
- Ross (1977) defined requirements definition as saying why a new system is needed, what system features will satisfy this context, and how the system is to be constructed.
- Zave (1997) defined RE as concerned with the real-world goals, functions, and constraints of software systems, and with their link to precise specifications of software behavior.
System Requirements vs. Software Requirements
- Software-to-be refers to the software to be developed, which is part of the machine and a component of the system-to-be.
- Environment refers to all other components of the system-to-be, including people, devices, and pre-existing software.
The WHY Dimension
- The WHY dimension involves identifying, analyzing, and refining the system-to-be's objectives to address the analyzed deficiencies of the system-as-is and in alignment with business objectives.
The WHAT Dimension
- The WHAT dimension involves identifying and defining the system-to-be's functional services to satisfy the identified objectives, according to quality constraints, and based on realistic assumptions about the environment.
The WHO Dimension
- The WHO dimension involves assigning responsibilities for the objectives, services, and constraints among system-to-be components, based on their capabilities and the system's objectives.
Setting the Scene (Summary)
- RE involves understanding the problem world and the machine solution, and scopes the WHY, WHAT, and WHO dimensions.
- RE involves descriptive and prescriptive statements, and categories of requirements, including functional and non-functional.
- The requirements lifecycle involves actors, processes, and products, and targets specific qualities and defects to avoid.
Identify responsibilities for objectives and services in a system among its components, considering their capabilities and system objectives. Examples include assigning tasks in an airport train control system.
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