Learn
Games

5.4 - Non-Functional Requirements (NFRs)

Interactive Audio Lesson

Listen to a student-teacher conversation explaining the topic in a relatable way.

Introduction to Non-Functional Requirements

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

Teacher
Teacher

Today we're discussing Non-Functional Requirements, or NFRs. These are the requirements that define how a system should behave rather than what it should do. Can anyone share an example of a non-functional requirement?

Student 1
Student 1

Maybe something like how fast the system loads?

Teacher
Teacher

Exactly! A requirement like 'The system should load in under 2 seconds' is a great example of a performance NFR. These requirements focus on system qualities like performance, security, and usability.

Student 2
Student 2

So, how do NFRs differ from functional requirements?

Teacher
Teacher

Good question, Student_2! While functional requirements are concerned with the specific functionalities of the system, NFRs set the standards for how well those functionalities perform. Think of it as 'how well' versus 'what.'

Student 3
Student 3

Can you explain how we can measure NFRs?

Teacher
Teacher

NFRs need to be measurable or testable. For example, we can measure response time in seconds, usability through user testing scores, or security through the number of vulnerabilities identified.

Teacher
Teacher

To summarize, NFRs focus on the qualities of the system, are often cross-cutting, and must be measurable. Keep these principles in mind as we move forward!

Types of Non-Functional Requirements

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

Teacher
Teacher

Now, let's delve into the various types of NFRs. Can anyone list some NFR types we discussed?

Student 4
Student 4

Performance, security, and usability?

Teacher
Teacher

Spot on, Student_4! Performance, security, usability, reliability, scalability, and compliance are the main types. Let's look at them in detail. Performance could involve response times—like the homepage loading quickly.

Student 1
Student 1

What about security?

Teacher
Teacher

Great point! Security focuses on safeguarding data, such as requiring authentication or encryption. It ensures that only authorized users can access certain functionalities.

Student 3
Student 3

Why do we also need reliability?

Teacher
Teacher

Reliability is crucial because it measures how consistently the system performs over time, ensuring that users can trust your system to be available when needed.

Teacher
Teacher

Summarily, each type of NFR addresses a unique dimension of system quality which is vital for user satisfaction and operational effectiveness.

BA's Role in NFRs

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

Teacher
Teacher

Let's discuss the role of Business Analysts in the context of NFRs. What do you think is the primary task of a BA regarding NFRs?

Student 2
Student 2

I think they need to gather those requirements from stakeholders.

Teacher
Teacher

Absolutely, Student_2! BAs are responsible for eliciting NFRs from stakeholders through interviews and assessments. They also need to ensure these requirements are documented correctly.

Student 4
Student 4

What if there are conflicting NFRs?

Teacher
Teacher

Great question! Managing conflicts between requirements is crucial. A BA needs to facilitate discussions to prioritize requirements based on business objectives and user impact, sometimes using negotiation.

Teacher
Teacher

In summary, BAs are instrumental in identifying, documenting, and managing NFRs to ensure the final system aligns with user needs and expectations.

Introduction & Overview

Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.

Quick Overview

Non-Functional Requirements (NFRs) focus on how a system should perform rather than what it should do.

Standard

NFRs define the qualities of a system, such as performance, security, usability, and reliability. These requirements are crucial for ensuring that a system meets user expectations and operational constraints, often across multiple functional components.

Detailed

Non-Functional Requirements (NFRs)

Non-Functional Requirements (NFRs) are essential specifications that dictate how a system should operate, going beyond mere functional requirements. Unlike functional requirements that specify what the system will do, NFRs focus on how well the system performs these functions, emphasizing qualities such as performance, security, usability, and reliability.

  • Key Characteristics of NFRs:
  • Quality-related (performance, security, usability, etc.)
  • Often cross-cutting across many functional components
  • Must be measurable or testable
  • Common Types of NFRs:
  • Performance: Response time, throughput. For example, “The system should load the homepage in under 2 seconds.”
  • Security: Authentication, encryption. For example, “Data should be encrypted in transit and at rest.”
  • Usability: Intuitive design, accessibility.
  • Reliability: System uptime, error handling requirements.
  • Scalability: Ability to grow with the demand, such as supporting 5,000 concurrent users.
  • Compliance: Adherence to laws and regulations, for instance, GDPR and HIPAA.

In the realm of requirement engineering, BAs play a pivotal role in eliciting and documenting NFRs to ensure alignment with stakeholder expectations and compliance with industry standards. They collaborate closely with architects and developers to integrate these requirements into the system design and ensure they are assessable during testing.

Audio Book

Dive deep into the subject with an immersive audiobook experience.

Definition of NFRs

Unlock Audio Book

Signup and Enroll to the course for listening the Audio Book

Requirements that define how the system should behave, focusing on system qualities and constraints rather than specific behaviors.

Detailed Explanation

Non-Functional Requirements (NFRs) are essential aspects of system specifications that dictate how well a system performs rather than what it does specifically. While Functional Requirements outline the actions or tasks the system needs to perform, NFRs focus on the qualities of those functions. This includes considerations like how secure the system is, how fast it responds, and how easy it is to use.

Examples & Analogies

Think of NFRs like the rules that govern a sporting event. For example, in basketball, the rules specify dimensions of the court and how long play can last (NFRs). While the players execute specific plays (functional requirements), it’s these governing rules that dictate how the game is conducted.

Characteristics of NFRs

Unlock Audio Book

Signup and Enroll to the course for listening the Audio Book

Key Characteristics:
● Quality-related (performance, security, usability, etc.)
● Often cross-cutting across many functional components
● Measurable or testable

Detailed Explanation

NFRs share several key characteristics. They are primarily quality-related, meaning they describe the qualities the system must hold. They are often cross-cutting, affecting many functional areas of the system rather than being tied to a single function. Moreover, they are measurable or testable, which means you can evaluate whether or not the NFRs are met using concrete metrics.

Examples & Analogies

Imagine you are cooking a dish where you want it to taste good (taste being an NFR). While the ingredients and recipe (functional requirements) determine how you prepare the dish, tasting and adjusting seasoning based on flavor (measurable quality) is akin to ensuring that your NFR is fulfilled.

Examples of NFRs

Unlock Audio Book

Signup and Enroll to the course for listening the Audio Book

Examples:
● The system should load the homepage in under 2 seconds
● The application must support 5,000 concurrent users
● Data should be encrypted in transit and at rest

Detailed Explanation

Examples of NFRs highlight their diverse nature. For instance, requiring the system to load quickly (first example) targets performance, while supporting a large number of users (second example) emphasizes scalability. The third example ensures security by specifying that data is encrypted during transmission and storage. Each of these examples showcases how system qualities are essential to its overall functionality and user satisfaction.

Examples & Analogies

Consider a theme park. The requirement for rides to accommodate thousands of visitors simultaneously (scalability) ensures everyone has the opportunity to enjoy the attractions. Quick waiting times (performance) enhance the visitor experience, just like how the encryption of personal data protects their privacy.

Types of NFRs

Unlock Audio Book

Signup and Enroll to the course for listening the Audio Book

Types of NFRs:
● Performance (e.g., response time, throughput)
● Security (e.g., authentication, encryption)
● Usability (e.g., intuitive design, accessibility)
● Reliability (e.g., system uptime, error handling)
● Scalability (e.g., ability to grow with demand)
● Compliance (e.g., GDPR, HIPAA)

Detailed Explanation

NFRs come in various types, each focusing on different aspects of system quality. Performance addresses how fast and efficiently a system operates. Security relates to how well user data is protected. Usability pertains to how user-friendly the system is. Reliability ensures the system is dependable. Scalability looks at how well the system can handle increased loads, and compliance ensures the system adheres to legal regulations. Each type plays an important role in fulfilling overall user and organizational requirements.

Examples & Analogies

Think of a high-performance car as an analogy. The engine's response time and speed (performance) matter for racing. The brakes and safety features (security) ensure drivers are kept safe, while the dashboard interface (usability) must be intuitive for the driver. The car must also perform reliably over time (reliability) and be able to handle different conditions, like increased passenger weights (scalability), all while following automotive regulations (compliance).

Deliverables Related to NFRs

Unlock Audio Book

Signup and Enroll to the course for listening the Audio Book

Deliverables:
● NFR Documentation
● Service Level Agreements (SLAs)
● System Design Constraints

Detailed Explanation

When working with NFRs, several key deliverables must be created. NFR Documentation is a detailed account of all NFRs outlined for the project. Service Level Agreements (SLAs) stipulate the expected service standards and responsibilities. System Design Constraints are restrictions or guidelines that will impact how the system is built and operate, ensuring that the NFRs can be achieved.

Examples & Analogies

Consider building a custom home. The NFR Documentation would be like the blueprint that specifies quality and performance standards for materials. SLAs could represent contracts with builders detailing completion times and quality checks. System Design Constraints would involve zoning laws or budget limits that must be respected while building the house, ensuring that the final outcome meets the owner’s expectations for safety, comfort, and style.

BA's Role in NFRs

Unlock Audio Book

Signup and Enroll to the course for listening the Audio Book

BA's Role:
● Elicit NFRs through stakeholder interviews and system reviews
● Ensure NFRs are testable and documented
● Collaborate with architects and developers to plan for NFRs

Detailed Explanation

The Business Analyst (BA) plays a crucial role when it comes to NFRs. They are responsible for gathering these requirements through discussions with stakeholders and analyzing the systems. Ensuring NFRs are testable means they are articulated in a way that allows for verification once the system is implemented. Finally, collaborating with architects and developers ensures that NFRs can be incorporated into the system's design.

Examples & Analogies

Think of the BA as a project manager for a movie. They interview the cast and crew (stakeholders) to understand required performances and production values (NFRs). They need to ensure that all aspects — from acting, lighting, to special effects — are achievable and can be tested during production, ensuring the final movie meets quality standards before its release.

Definitions & Key Concepts

Learn essential terms and foundational ideas that form the basis of the topic.

Key Concepts

  • Non-Functional Requirements: Requirements focusing on system qualities rather than functionalities.

  • Performance: A type of NFR regarding response times and efficiency.

  • Security: NFR concerning data protection and access control.

  • Usability: NFR related to user-friendliness and ease of use.

  • Reliability: Emphasizes consistent domain performance over time.

  • Scalability: Refers to how well a system can grow to handle increased demand.

  • Compliance: Encompasses adherence to relevant laws and regulations.

Examples & Real-Life Applications

See how the concepts apply in real-world scenarios to understand their practical implications.

Examples

  • An example of a performance NFR is 'The system should load in less than 2 seconds.'

  • A security NFR may state 'Data must be encrypted both in transit and at rest.'

  • A usability requirement can specify 'The system shall have an intuitive layout that complies with accessibility standards.'

Memory Aids

Use mnemonics, acronyms, or visual cues to help remember key information more easily.

🎵 Rhymes Time

  • To build a system great, focus on how it rates, performance, security, and usability – don't let them wait!

📖 Fascinating Stories

  • Imagine a castle (the system) that not only protects (security) but also allows guests (users) to explore quickly (performance) and easily (usability) without getting lost.

🧠 Other Memory Gems

  • Remember 'P-S-U-R-S-C' for NFRs: Performance, Security, Usability, Reliability, Scalability, Compliance.

🎯 Super Acronyms

Use 'FAST' to remember key parts of NFRs

  • 'Functionality
  • Availability
  • Security
  • Testing' - all crucial for user satisfaction.

Flash Cards

Review key concepts with flashcards.

Glossary of Terms

Review the Definitions for terms.

  • Term: NonFunctional Requirements (NFRs)

    Definition:

    Requirements that define how a system should behave, focusing on qualities like performance, security, and usability.

  • Term: Performance

    Definition:

    The measure of how quickly and efficiently a system performs its functions.

  • Term: Security

    Definition:

    The measures taken to protect data and resources from unauthorized access and vulnerabilities.

  • Term: Usability

    Definition:

    The degree to which a system is user-friendly and easy to navigate.

  • Term: Reliability

    Definition:

    The ability of a system to function consistently and correctly over time.

  • Term: Scalability

    Definition:

    The capacity of a system to handle an increasing number of users or transactions.

  • Term: Compliance

    Definition:

    The requirement for a system to adhere to relevant laws and regulations.