Software Requirements Engineering

Requirements Engineering and Modeling

• A requirement is defined as a condition or capability needed by a user for problem-solving or achieving an objective.
• It also refers to a condition that a system must meet to satisfy contracts, standards, or specifications.
• Requirements collection involves identifying the needed capabilities in final deliverables.

Categories of Requirements

• Functional Requirements

  • Define what the deliverable must do; describe its characteristics in non-technical language.
  • Focus on "what" is needed, not "how" it will be achieved.

• Non-Functional Requirements (NFR)

  • Concern product properties and user expectations.
  • Split into two subcategories: technical and non-technical.

Non-Functional Requirements

• Technical NFRs

  • Include attributes like scalability, reliability, security, usability, and maintainability.

• Non-Technical NFRs

  • Encompass regulatory and compliance aspects, cultural influences, and political factors.

Challenges in Requirements Gathering

• Customers often struggle to articulate their requirements clearly, leading to unprioritized and conflicting capabilities.

System Analysis Phase Overview

• Aims to understand the proposed project and ensure it aligns with business requirements.
• Establishes a strong foundation for the subsequent stages of system development.

Requirements Modeling

• Involves fact-finding to assess the current system and identify new system requirements.
• Requirements categorized include outputs, inputs, processes, performance, and security.

Requirements Collection Techniques

• Utilize various methods for gathering requirements, including:
  • Interviewing stakeholders
  • Conducting focus groups and workshops
  • Distributing questionnaires and surveys
  • Observation of current practices
  • Prototyping to visualize ideas

Team-Based Techniques

• Joint Application Development (JAD)

  • Encourages active user participation in the development process.

• Rapid Application Development (RAD)

  • Focuses on quick production and revision through user feedback.

• Agile Development

  • Emphasizes iterative development and flexible response to change.

Other Classification of Requirements

• Normal Requirements
• Expected Requirements
• Exciting Requirements
  • Each category defines different user needs and expectations from the system.

Requirements Overview

• Customers often struggle to articulate system requirements clearly, resulting in unprioritized and conflicting capabilities.

Non-Functional Requirements (NFR)

• Two categories exist:
  • Technical NFRs: Focus on software attributes like scalability, reliability, availability, recoverability, maintainability, security, usability, and integrity.
  • Non-Technical NFRs: Address regulatory issues, government standards, cultural expectations, and political contexts.

System Analysis Phase

• Objectives include understanding the proposed project, ensuring alignment with business requirements, and laying a foundation for system development.

Requirements Modeling

• Involves fact-finding to describe the current system and identify new system requirements, such as:
  • Outputs, Inputs, Processes, and Performance.

Agile Development Methodology

• Advantages: Flexibility in change management, strong team interaction, frequent deliverables that validate the project, and reduced risks.
• Disadvantages: Potential for evolving user requirements leading to significant changes in project scope.

Business Process Modeling (BPM)

• Graphically illustrates business processes and uses standard languages for requirement modeling.
• Diagrams include "pool" for overall process depiction and "swim lanes" for subprocesses.

Data Flow Diagrams (DFD)

• Used to show data storage, processing, and transformations using defined symbols like rectangles, circles, and arrows.

Use Case Diagrams

• Represents user interactions with the system, where users are depicted as actors performing specific roles.

System Requirement Checklist

• System requirements are essential characteristics/features necessary for business compliance and user satisfaction.
• Categories include Outputs, Inputs, Processes, Performance, and Controls.

Fact-Finding Techniques

• Collects information vital for understanding system requirements and includes questions such as Who, What, Where, When, How, and Why.
• Distinguishes between current operations and proposed enhancements.

Interview Process

• A structured meeting aimed at gathering information from individuals.
• Steps include determining interviewees, establishing objectives, preparing questions, conducting interviews effectively, documenting outcomes, and evaluating insights.

Interview vs. Questionnaires

• Interviews gather in-depth information from individuals but are time-consuming and less economical.
• Questionnaires reach a larger audience economically but offer lower flexibility and immediate feedback.

This quiz focuses on the categories of requirements in software engineering, specifically functional and non-functional requirements. It also references the IEEE Standard Glossary of Software Engineering Terminology, providing insights into understanding technical and non-technical requirements. Test your knowledge on this crucial aspect of software development.