Introduction

In this guide, you will find examples, definitions and a complete overview of how to work with non-functional requirements in designing and building IT systems.

What are non-functional requirements?

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

Categories of non-functional requirements

Non-functional requirements can be divided into two categories:

• Quality characteristics: These are the characteristics of the system that determine its overall quality. Examples of quality attributes include security, performance, and ease of use.
• Restrictions: These are the restrictions imposed on the system. Examples of constraints include time, resources, and the environment.

Advantages of non-functional requirements

There are several advantages of non-functional requirements; they help ensure that the system:

• Meets the user’s needs.
• Is fit for purpose.
• Is scalable, secure, and reliable.
• Is easy to use and maintain.

Disadvantages of non-functional requirements

There are several disadvantages of non-functional requirements because they can:

• Be challenging to understand and implement.
• Be time-consuming and expensive to test.
• Affect the functionality of the system if not implemented correctly.

Non-functional requirements vs functional requirements

As the name implies, functional requirements describe the system’s features to be designed. It explains what the system will be like and how it will work to satisfy users’ needs. They clearly describe how the system should respond to a particular command, the features, and what users expect.

Non-functional requirements explain the limitations of the system to be designed. These requirements have no impact on the functionality of the application. In addition, there is a common practice of subclassifying the non-functional requirements into different categories:

• Interface
• Reliability
• Security
• Performance
• maintenance
• Standards

It is an excellent practice to subclassify the non-functional requirements. It helps when making a checklist of the criteria to be met in the system to be designed.

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

The only difference is that an IT system cannot meet all functional requirements. On the other hand, the IT system will give you the desired result even when it fails to meet the non-functional requirements.

Examples of non-functional requirements

Here are some examples of non-functional requirements for IT systems:

• Security: The system must be secured against unauthorised access.
• Performance: The system must handle the required number of users without performance degradation.
• Scalability: The system must scale up or down as needed.
• Availability: The system must be accessible when needed.
• Maintenance: The system must be easy to maintain and update.
• Migration: The system must be able to run on different platforms with minimal changes.
• Reliability: The system must be reliable and meet the user’s requirements.
• Usability: The system must be easy to use and understand.
• Compatibility: The system must be compatible with other systems.
• Compliance: The system must comply with all applicable laws and regulations.

Non-functional requirements are essential for any system. They help to ensure the system meets the user’s needs and functions as intended. Considering all the non-functional requirements is critical before designing and developing an IT system.

What is the collection of non-functional requirements?

Collecting non-functional requirements is identifying and documenting the non-functional requirements for an IT system. You can do that through interviews, surveys, focus groups or other methods. Once the non-functional requirements have been unified, they can be analysed and prioritised.

Collecting non-functional requirements is an essential part of developing an IT system. It helps to ensure that all needed requirements are identified and receive the appropriate attention. Without a comprehensive collection of non-functional requirements, creating a system that meets the user’s needs would be difficult.

What are non-functional requirement evocation techniques?

Techniques for inducing non-functional requirements are essential to identify and documenting a system’s non-functional requirements. Many different techniques can be used, such as interviews, surveys, focus groups, or other methods. Once the non-functional requirements have been unified, they can be analysed and prioritised.

The manufacturing process for non-functional requirements is an essential part of the development of a system. The process helps ensure that all the requirements are identified and receive the appropriate level of attention. With a detailed evocation of non-functional requirements, developing a system that meets the user’s needs would be easier.

Why analyse non-functional requirements?

Non-functional requirements analysis is the process of analysing the non-functional requirements of a system. Please do this by reviewing the requirements, evaluating them, and prioritising them. The goal of analysing non-functional requirements is to ensure they are identified and will receive the appropriate level of attention.

Non-functional requirements analysis is an essential part of the specification of an IT system. The analysis helps ensure that all the requirements are identified and receive the appropriate level of attention. With a thorough Non-Functional Requirements analysis, developing a system that meets all the user’s needs will be easy.

Best practices for writing non-functional requirements

A few best practices should be followed when writing non-functional requirements. These include:

1. Make sure that the IT system requirements are clear and precise.
2. Be specific about what is required.
3. Avoid using jargon.
4. Use plain language.
5. Make sure the requirements are achievable.
6. Be realistic about what can be achieved.
7. Prioritise the requirements.
8. Keep requirements flexible.
9. Review and revise the criteria as needed.
10. Get feedback from stakeholders on the conditions.

Non-functional requirements are an essential part of any system development project. Following these best practices ensures that your non-functional requirements are clear, precise, and achievable.

Conclusion

The non-functional requirements help ensure that the system meets the user’s needs and that the IT system can function as intended. Any IT project must gather non-functional requirements, analysis, and follow best practices. Following these guidelines ensures that your non-functional requirements are clear, precise, and achievable.

Non-functional requirements are also limitations or requirements imposed on the system. They specify the software’s quality characteristics and address scalability, maintenance, performance, portability, security, and reliability. Thus, non-functional requirements address important quality issues for software systems. And don’t forget those non-functional requirements can work against one another; for example, security can be a barrier to usability.