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What are Non-Functional Requirements: Examples, Definition, Complete Guide

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What are Non-Functional Requirements: Examples, Definition, Complete Guide

What are Non-Functional Requirements? Non-Functional Requirements (NFRs) are the constraints or the requirements imposed on the system. They specify the quality attribute of the software. Non-Functional Requirements deal with issues like scalability, maintainability, performance, portability, security, reliability, and many more. Non-Functional Requirements address vital issues of quality for software systems. In this article, we will try to understand Non-Functional Requirements in detail with some examples.

What are Non-Functional Requirements?

Non-functional requirements (NFRs) are the constraints imposed on a system that define its quality attributes. They are usually denoted by adjectives such as security, performance, and scalability. Non-functional requirements are important because they help ensure that the system meets the needs of the user.

Categories of Non-Functional Requirements

Non-Functional Requirements can be divided into two categories:

  1. Quality Attributes: These are the characteristics of the system that determine its overall quality. Examples of quality attributes include security, performance, and usability.
  2. Constraints: These are the limitations imposed on the system. Examples of constraints include time, resources, and environment.

Advantages of Non-Functional Requirements

There are several advantages of Non-Functional Requirements:

  1. They help ensure that the system meets the needs of the user.
  2. They help ensure that the system is fit for purpose.
  3. They help ensure that the system is scalable, secure, and reliable.
  4. They help ensure that the system is easy to use and maintain.

Disadvantages of Non-Functional Requirements

There are several disadvantages of Non-Functional Requirements:

  1. They can be difficult to understand and implement.
  2. They can be time-consuming and expensive to test.
  3. They can impact the functionality of the system if not properly implemented.

Non-Functional Requirements Vs Functional Requirements

Functional Requirements, as the name suggests, describe the functions of the system to be designed. It is a description of what the system will be and how it will function to satisfy user needs. They provide a clear description of how the system is supposed to respond to a particular command, the features, and what the users expect. 

Non-Functional Requirements explain the limitations and constraints of the system to be designed. These requirements do not have any impact on the functionality of the application. Furthermore, there is a common practice of sub-classifying the non-functional requirements into various categories:

  • User Interface
  • Reliability 
  • Security
  • Performance
  • Maintenance
  • Standards 

Sub-classifying the non-functional requirements is a good practice. It helps when creating a checklist of the requirements that are to be met in the system to be designed. 

Non-functional requirements are as important as functional requirements. If functional requirements specify what a system should do, non-functional requirements describe how it will do it. For example, the new application shall provide us with the final list of all connected users. That is a part of functional requirements. If the requirement says that the system would only work on a Windows and a Linux system, that would be a part of non-functional requirements. 

The only difference between the two is that the system can not function without satisfying all the functional requirements. On the other hand, the system will give you the desired outcome even when it does not satisfy the non-functional requirements.

Examples of Non-Functional Requirements

Here are some examples of Non Functional Requirements:

  1. Security: The system must be secure from unauthorized access.
  2. Performance: The system must be able to handle the required number of users without any degradation in performance.
  3. Scalability: The system must be able to scale up or down as needed.
  4. Availability: The system must be available when needed.
  5. Maintenance: The system must be easy to maintain and update.
  6. Portability: The system must be able to run on different platforms with minimal changes.
  7. Reliability: The system must be reliable and meet the requirements of the user.
  8. Usability: The system must be easy to use and understand.
  9. Compatibility: The system must be compatible with other systems.
  10. Compliance: The system must comply with all applicable laws and regulations.

Non-functional requirements are essential for any system. They help ensure that the system meets the needs of the user and is able to function as intended. It is important to carefully consider all of the Non-Functional Requirements before designing and developing a system.

What is Non-Functional Requirements Gathering?

Non-Functional Requirements gathering is the process of identifying and documenting the Non-Functional Requirements for a system. This can be done through interviews, surveys, focus groups, or other methods. Once the Non-Functional Requirements have been gathered, they can be analyzed and prioritized.

The Non-Functional Requirements gathering process is an important part of developing a system. It helps ensure that all of the necessary requirements are identified and that they are given the appropriate level of attention. Without a thorough Non-Functional Requirements gathering process, it would be difficult to develop a system that meets the needs of the user.

What are Non-Functional Requirement Elicitation Techniques?

Non-functional requirement elicitation techniques are used to identify and document the Non-Functional Requirements for a system. There are many different techniques that can be used, such as interviews, surveys, focus groups, or other methods. Once the Non-Functional Requirements have been gathered, they can be analyzed and prioritized.

The Non-Functional Requirements elicitation process is an important part of developing a system. It helps ensure that all of the necessary requirements are identified and that they are given the appropriate level of attention. Without a thorough Non-Functional Requirements elicitation process, it would be difficult to develop a system that meets the needs of the user.

What is Non-Functional Requirement Analysis?

Non-functional requirement analysis is the process of analyzing the Non-Functional Requirements for a system. This can be done by reviewing the requirements, evaluating them, and prioritizing them. The goal of Non-Functional Requirements analysis is to ensure that all of the necessary requirements are identified and that they are given the appropriate level of attention.

Non-functional requirement analysis is an important part of developing a system. It helps ensure that all of the necessary requirements are identified and that they are given the appropriate level of attention. Without a thorough Non-Functional Requirements analysis, it would be difficult to develop a system that meets the needs of the user.

Best Practices for Writing Non-Functional Requirements

There are a few best practices that should be followed when writing Non-Functional Requirements. These include:

  • Make sure the requirements are clear and concise.
  • Be specific about what is required.
  • Avoid using jargon.
  • Use plain language.
  • Make sure the requirements are achievable.
  • Be realistic about what can be achieved.
  • Prioritize the requirements.
  • Keep the requirements flexible.
  • Review and revise the requirements as needed.
  • Get feedback from stakeholders on the requirements.

Non-Functional Requirements are an essential part of any system development project. By following these best practices, you can ensure that your Non-Functional Requirements are clear, concise, and achievable.

Conclusion

Non-Functional Requirements are an important part of developing a system. They help ensure that the system meets the needs of the user and is able to function as intended. Non-Functional Requirements gathering, analysis, and best practices are essential for any project. By following these guidelines, you can ensure that your Non-Functional Requirements are clear, concise, and achievable.

Non-Functional Requirements are the constraints or the requirements imposed on the system. They specify the quality attribute of the software. Non-Functional Requirements deal with issues like scalability, maintainability, performance, portability, security, reliability, and many more. Non-Functional Requirements address vital issues of quality for software systems.

Non-Functional Requirements are an important part of any system development project. By following these best practices, you can ensure that your Non-Functional Requirements are clear, concise, and achievable. If you want to learn more about functional requirements or get started with creating them yourself, request a free 30-day trial at Visure Requirements ALM Platform today.

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