Functional And Non Functional Requirements In Software Engineering

December 10, 2024

No wonder businesses looking to ensure excellent quality assurance in their project know how essential the strategic blend of two requirement types is. That is none other than functional and non-functional testing. Knowing their differences is necessary for testing and QA teams, as each uniquely assesses an application.

Remember, successful software development requires in-depth planning and tracking of both functional and non-functional requirements. Project analysis indirectly helps the business analysts and the project manager define the needs and conditions to be met, set the right goals, and create necessary product documentation. 

So, why do these requirements matter in software development? This blog fits your business needs best. Below, we have shared a detailed guide on the main distinctions, types, and examples of functional and non-functional requirements for any software development.

What Are Functional Requirements

A functional requirement in software engineering defines software’s interactive and usable elements. Functional requirement typically describes features businesses designed to allow the targeted audience to complete desired actions to reach a specific goal.

Functional requirements are a software’s specific features that justify the behavior within inputs and outputs. However, you can also justify functional requirements as your developed software’s basic behaviors.

In other words, if we talk about the functional requirements, then it is the specification of the product’s features or functions. Business analysts usually craft these. This group helps the business to interact with their clients to analyze proper user requirements in software requirements and convert them into specifications. 

Here are some requirements:

• Business requirements 
• Reporting requirements
• Administrative functions
• Authentication
• Certification requirements

Let’s understand through this example: when you sign into a website, you receive a mail that confirms your login on the website. Similarly, in the case of software engineering, sending email is referred to as the functional requirement at the development stage. 

What Are Non-Functional Requirements

Well, when talking about the non-functional requirements of projects, it directly refers to the set of specifications that describe the system’s operation capabilities and constraints. These are usually the requirements that indicate how effectively the software operates, including things like speed, security, reliability, data integrity, etc. 

Many times, it is referred to as the quality attributes or software quality requirements since they describe a different aspect of how the product works. While functional requirements define fundamental behavior, non-functional requirements determine how the system will carry out these functions. Let’s bring out the same email example again to understand this better. 

Functional requirement automatically sends an email notification. Then, the non-functional requirements will ensure the email is typically dispatched within 5 seconds of sign-up. 

Here are the requirements of non-functional requirements: 

• Usability 
• Reliability 
• Performance 

Likewise, functional requirements and non-functional requirements do not create a backbone for any software. This directly indicates the software will still run smoothly even if the non-functional requirements are not aligned. But you must remember that the non-functional requirement elaborates a performance characteristic of the system. 

So, one should not downplay the role of non-functional requirements. While functional requirements aim at the audience’s basic needs in software development, non-functional requirements are more user-centric. Software taking more time than usual to load can still cater to the functional requirement but can not hit the mark in other areas.

Functional And Nonfunctional Requirements Examples

When comparing functional requirements and non-functional requirements, analyze a specific feature or functionality that software must align with the stakeholders and the business-critical needs. Likewise, you can analyze from the name itself that they focus on totally different aspects. Want to know about it in depth? 

Here, we share the differences between functional and non-functional requirements with detailed examples.

Functional Requirements Types And Examples

After you are aware of the non-functional requirements, let’s understand the other group examples of non-functional groups. Here are some types and examples of a functional group:

Functional Requirement Types

• Business Regulations
• Certification Requirements
• Reporting Requirements
• Administrative Functions
• Authorization Levels
• Audit Tracking
• External Interfaces
• Data Management
• Legal and Regulatory Requirements

Functional Requirement Examples

• Emails are sent each time an action is taken on the software.
• Site audiences use their numbers for account verification.
• The potentiality to subscribe to an email newsletter.
• A button to report problems in software.
• The leverage to enter an ID and password to authenticate a login.
• CRUD audiences can modify, view, update, or remove account details.
• The feature enables users to verify accounts through external services.
• Modify cart items during online shopping or proceed to checkout.
• A feature to print or download a page from the system.
• ASoftwaredelivers updates, marketing material, or notifications to users.

These are some of the key types of functional with examples. Now, let’s understand the non-functional requirement types and examples!

Non-Functional Requirement Examples

The key groups of non-functional requirements are usually scalability, performance, portability, reliability, availability, compatibility, maintainability, localization, security, and usability. There are a few other types that can make it to your checklist, too. Here are some of the types explained with examples: Non-Functional Requirement Types and Examples

• Performance: How the system returns results.
• Scalability: How much does the performance change with the higher workloads? 
• Profitability: The hardware and operating systems, along with the versions the system works on. 
• Compatibility: If the system conflicts with other systems or software? 
• Reliability: The frequency of software to witness failures.
• Maintainability: How long does it take to fix the issue when it arises? 
• Availability: The average downtime of a system. 
• Security:  How well are the systems and their data protected against attacks? 
• Usability: How simple is it to use software? 

Written Documents Of Functional and Nonfunctional Requirements

Well, functional and non-functional requirements do not materialize in thin air. They are written in many forms, for example— software requirement specification documentation, user stories, use cases, etc. However, if you are thinking of developing software with functional and non-functional requirements, then ensure to explore the overall software development strategy. 

Let’s understand the multiple forms of functional and non-functional requirements in depth:

Software Requirement Specification

Specification documentation is a widely used software requirement. The information in these specified documents includes which functions a software must consist of and how it must perform. In other words, it is the detailed description of all the features a product comprises. 

The documentation’s key role is to align the client’s requirements with the development team’s accessibility. The SRS identifies even small details. Making it an essential document for evaluating the actual cost and development time. 

Typically, it includes the following sections: 

• Introduction: It aims to cover the meaning of the terms (document conventions), purposes, and references.
• Overall description: It covers an overall understanding of software product features and design and implementation constraints. 
• System features: This holds up the evaluation of how each function will work.
• External interface requirements: Describes how the software needs to interact with the world.
• Functional requirements: Software quality, performance needs, and compliance measurements.

User stories 

This is a documented description of software functionality from the audience’s POV. The user story justifies what exactly the user wants the software to do. These are the product specifications that are based on real-life examples and the user’s behalf. Typically, these are arranged in just a few sentences and are based on the following structure:

• As a ( user role)
• I want to (user’s objective)
• So that (Reason)

For example, as an admin, I want to add productive features to software development so that users can efficiently use the software. 

Acceptance criteria must accompany user stories. These are the conditions the software must ensure to satisfy to be accepted by a user, stakeholders, or a product owner.

User stories are required to shift the aim from writing down the product’s features to a high-end discussion. These user stories are put on the developers’ team notes to use the stories while brainstorming during planning meetings.  

However, let’s understand this form through a business that has invested in a ride-sharing app development like Uber Clone. Here is the user story created for this project to help you understand easily: 

User Story 1: Driver Profile and Ratings

As a driver, I want to create a profile that includes my vehicle details and receive ratings from passengers so that I can build trust and improve my chances of getting more ride requests.

User Story 2: Payment Options

As a user, I want to choose from multiple payment options (credit card, digital wallets, etc.) so that I can pay for my rides in a way that is most convenient for me.

User Story 3: Ride Booking

As a passenger, I want to book a ride by entering my pickup and drop-off locations so that I can easily get to my destination without any hassle.

Use Case 

Similar to the user story, it is also part of any full-cycle software development like agile methodology. These are real-time cases that reflect all possible ways a user can interact with the system. 

Although these terms, user stories and use cases, sound quite similar, they are so different in reality. While a user story reflects the actual objective of a feature, a use case evaluates the steps or the flow that leads to the objectives. There are usually three key elements use case includes: 

• Actor: Actors are audiences that use the software.
• System: The system is usually evaluated by the functional requirements that define the intended behavior of the software. 
• Goals: This focuses on the interaction between the users and the systems, which are outlined as goals. 

For instance, if you want to create an e-commerce platform like Temu Clone, you should consider several actors: buyers, sellers, wholesale dealers, auditors, suppliers, distributors, customer care, etc.

Now, let’s forecast the actions of these actors. Some of them may are as including:

• Both seller/buyer “sign in or search”
• buyers/seller actions— “Create an account”
• User action: searching onsite, adding an item to favorites, trying to contact, etc. 

Hire Expertise Like RichestSft to Align the Requirement

While you are aware of how functional and nonfunctional requirements examples differ from each other, do you know what to do to make app development seamless? 

Well, Richestsoft is the best-in-class solution for your business needs. We bring a clear vision to project development and build multiple strategies to ensure that both functional and non-functional requirements are effectively met throughout the software development lifecycle.

Keep in mind the essential principle of thumb in the Agile setting states, “Functional software is preferred to detailed documentation.” By aligning to the Agile methodology or any appropriate full-cycle software development approach, our team sidesteps a lot of extensive documentation. For that reason, in our tasks, we prioritize User Stories and Acceptance criteria. The merging of the two documents elucidates the actions a team needs to follow and the functioning of a product.

Hiring us as your development partner helps businesses effectively manage both the functional and non-functional requirements of their projects. Our expertise ensures that all aspects of the software are thoroughly addressed. 

With our commitment, we ensure that we provide a high-quality product that meets both user expectations and business objectives. We are also a great approach that minimizes risks associated with project failure and maximizes the potential for delivering a robust software solution.

Conclusion

Overall, the functional and non-functional requirements have quite obvious differences. In simple terms, these are a single set of specifications required for your future software development. 

This requirement setup is also an essential step that comes with software development. This significantly helps businesses to analyze how the product will function smoothly in the long run. However, carefully consider who can help you figure out the specifications of your product more accurately. 

Thus, RichestSoft is all you need in this critical situation. Our team is always there to solve new challenges for business. Contact us to discuss your idea and think about how we could put it to life.