Home Web Development Functional vs Non Functional Requirements (NFR) | Importance

Functional vs Non Functional Requirements (NFR) | Importance

by Mariya Parackal

Most of the time, it’s been seen that product developers pay attention to functional requirements while neglecting non-functional requirements and their utility.

By prioritizing functional requirements (FR) over non-functional requirements (NFR), one can create a smart product, but later on, it may lead to a final product of poor-quality. 

The importance of non-functional requirements in product development goes way beyond cost containment. Companies with a well-laid-out requirement map generally perform better when it comes to cost containment, schedule management, and quality assurance.

But having the proper amount of non-functional requirements in the product development strategy can help the company achieve these goals. It is when the company has built-in functions that the non-functional requirements are fulfilled. 

The concept of NFR is based on the fact that there should always be some gap between non-functional and functional requirements that cannot be avoided. But if this gap can be adequately justified using other functional requirements, this gap cannot bridge the production process.

In other words, when you are dealing with functional requirements, you cannot avoid any of the non-functional requirements.

What are Functional Requirements (FR)?

Non-Functional Requirements

Functional Requirements are the product requirements expressed in terms of a business need. Functional requirements involve feasibility, estimation, documentation, testing, and modification as a requirement for obtaining a product or a process that meets business needs.

These must be expressible by the client to specify a budget and schedule for the entire project. These may be written in specifications (a document specifying the expected outputs), software requirements (the key constraints that motivate a software vendor to develop a product), or sometimes a combination of these.

Some examples of FRs are

  • Business rules
  • Administrative functions
  • Authentication
  • Transaction corrections
  • Audit tracking
  • Certification requirements
  • External interfaces, etc. 

Functional requirements are used in many phases of product development. It is a cardinal requirement used to form the initial requirements document – a Universal Specification Language (USL) that contains a description of the product and its intended use.

This is followed by a series of Functional Requirements Test (FRT) that verify the product’s design and its anticipated performance. The functional requirements set are used to derive requirements specifications that describe the product and identify the tests that will verify these specifications.

Functional Requirements -FR is used to describe the most critical requirements of a system in use.

Functional Requirements in product development help product owners and others to understand the process. Functional requirements are a set of technical assumptions about a product’s requirements and the data needed to satisfy these requirements.

These assumptions are based on the organization’s structure, including organizational culture, functional objectives, existing technology, time constraints, and funding.

These constraints must be considered to achieve the best possible technical solution to the problem of the organization. This way, the process of product development becomes more effective.

What are Non-functional Requirements (NFR)?

Non-Functional Requirements

For large and medium enterprises, non-functional requirements in product development is a common matter that is asked of a software development firm.

At the same time, the process is being carried on for software development. As the processes become more involved, many times, it is not only the company’s resources, which are being utilized for product requirements but also the software professionals’ skills.

The company intends to be sure that the process is cost-effective and does not compromise the quality of the products.

Non-functional requirements can be defined as the difference between what is needed to execute a functional requirement and what is technically required for its successful completion.

Most of the time, the difference is quite huge and can sometimes mislead a software development company’s decision-making process, which leads to delays in product development.

When this happens, one should not consider the difference between functional and non-functional in the process.

Some examples of NFRs are 

  • Performance
  • Response time
  • Utilization
  • Scalability
  • Availability
  • Capacity
  • Recoverability
  • Serviceability
  • Reliability
  • Maintainability, etc. 

NFR is the difference between what a company needs for a certain product to fulfill the requirement definition and what the product itself can do.

A functional requirement is usually a product requirement, but it considers the process’s overall efficiency and hence what the end-users require.

A non-functional requirement does not consider the overall efficiency of the process.

Hence is not a good indicator of the final product’s capability & performance.

Importance of NFR & Its Significance in Creating Flawless Products

Non-Functional Requirements

Sometimes, in the quest to create a product that impresses end-users through its functionality, most product managers and developers don’t pay heed to the significance of non-functional requirements.

They only focus on functional requirements and ultimately generate a low-quality and poorly scheduled product or service. That’s why it is necessary to give equal importance to both functional and non-functional requirements while undergoing a product development process.

The importance of NFR or non-functional requirements in mobile or app development process can be understood from cost reduction.

During the product development cycle, many activities are carried out based on functional requirements.

The process of converting functional requirements takes a lot of time and effort, resulting in high costs.

Product development is a big investment in the business. It involves cost, time, and workforce, and therefore all these factors have to be considered while planning any new invention or design.

The product development process needs careful attention and implementation of strategies. The above-mentioned fact can be concluded by saying that the product would not reach its actual quality and market without NFR in the product development process.

So, it can be said that the importance of non-functional requirements in the development cycle holds for both small and large organizations. NFR in the product development cycle holds great importance for any invention.

So, it is advised to follow this rule while planning any new product innovation: “It is better to meet your specifications than not to meet them.”

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