Development Friday November 26, 2021

Non-Functional Requirement in software engineering – Types and examples

What is a Non-functional requirement?

Non-functional requirements in software engineering describe a software system’s quality characteristics. They evaluate the software system based on its responsiveness, usability, security, portability, and other non-functional characteristics that are crucial to its success. 

In other words, NFRs also help to maintain functional needs in tune. NFRs, for example, provide attributes that make the product economical, simple to use, and accessible.

Table of contents

What is a Non-functional requirement?
Types of Non-functional requirements
Examples of Non-functional requirements 
Advantages of Non-functional requirements 
Disadvantages of Non-functional requirements 
Final words 

This article will explore you through the types of non-functional requirements, their examples, advantages, and disadvantages. 

Types of Non-functional requirements

Below are the main types of non-functional requirements. Let us discuss them one by one.

Performance

This criterion, which is one of the most prevalent NFRs states that all systems must be developed and implemented with an acceptable quality of performance as a minimum.

Scalability: Scalability evaluates the workloads that the system can handle. It refers to the system’s capacity to accept massive volumes (whether of users, throughput, or data). 

Speed: The speed of an application influences how quickly it reacts to requests. Speed also includes evaluating a system’s capacity to handle an increasing workload as you use many applications concurrently.

Portability: The portability of a system refers to how well it operates in one setting vs another. If the application performs on the new phone as it did on the previous one, it is extremely portable. To promote portability, you may build your applications to work effectively on many devices.

Compatibility: Compatibility describes how one system can coexist with another in the same environment. When additional apps are running on a device, highly compatible systems often perform effectively. People with various operating systems can also use the same applications. 

Security: Security ensures that any data included within the system or its components are safe from virus assaults or unauthorized access.

Capacity: A system’s capacity refers to the quantity of storage it provides. A device with a large storage capacity allows a user to customize additional settings or store large items such as lengthy papers or films. Capacity is often expressed on product labels in gigabytes or megabytes.

Reliability: This quality feature defines how probable it is that the system or its component will operate without failure for a certain amount of time under present conditions. Highly dependable technology continues to perform with the same or similar efficiency after extended use. 

Usability: The capacity to use a specific product is referred to as usability. How simple is the product to use? What defines the product’s user experience?

Availability: Availability represents the probability that a user will be able to access the system at a given moment in time. While it may be represented as a probability percentage, it can also be defined as a percentage of the time the system is operational within a certain period.

Data integrity: The term “data integrity” refers to the process of maintaining and ensuring the correctness and consistency of data over its entire lifespan.

Environment: External factors influence how well your system works in the environment. The environment of an application may also include the schedule on which it operates, such as 24 hours a day or just when the user activates it.

Localization: This quality describes how effectively a system or its component fits within the context of the future local market. Local languages, laws, currencies, cultures, spellings, and other factors are all part of the background.

Examples of Non-functional requirements 

Below are some examples of Non-functional requirements: 

  • After an overnight update, the procedure must be completed within 3 hours so that data is available by 8 a.m. local time.
  • The system must adhere to Web Content Accessibility Guidelines 2.1, and database security must adhere to HIPPA guidelines.
  • Before loading a new page, users will be required to enter an electronic signature.
  • Employees are never permitted to change their payment information. An attempt of this nature should be reported to the security administrator.
  • Every unsuccessful attempt by a user to access data must be documented on an audit trail.
  • Users must reset their first login password as soon as they log in successfully for the first time. Furthermore, the beginning should never be used again.
  • A website should be able to accommodate 20 million users without negatively impacting its performance.

Advantages of Non-functional requirements 

  • Non-functional requirements guarantee that the software system complies with legal and regulatory standards.
  • They assure the software system’s reliability, availability, and performance.
  • They guarantee a positive user experience and the simplicity of use of the application.
  • They contribute to the development of the software system’s security policy.

Disadvantages of Non-functional requirements 

The following are the disadvantages/drawbacks of the non-functional requirement:

  • None of the functional requirements may have an impact on the different high-level software subsystems.
  • Their implementation does not normally translate to a specific software sub-system, and it is difficult to alter non-functional code once the design phase is complete.
  • They need particular consideration throughout the software architecture/high-level design phase, which raises the cost.

Final words

Failing to meet non-functional requirements?

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