Non-Functional Requirements in Software Engineering
Non-Functional Requirements in software engineering are certain standards of quality that engineers can follow. These requirements help make sure the best possible performance of system software. In simple words, Non-Functional Requirements in software engineering help determine how a system should work and perform.
There are several types of Non-Functional Requirements in software engineering. The different types of NFMs include Performance, Stability, Security and Scalability. Each type helps ensure the best user experience. Non-Functional Requirements also make the development process easier for software engineers. Some examples of Non-Functional Requirements include software systems being available 24/7 and software being able to handle a large number of users at once. There are a lot of differences between Non-Functional and Functional Requirements in software engineering. Non-Functional Requirements focus on how systems should perform. On the other hand, Functional Requirements focus on what software systems can do. Functional Requirements place more importance on certain actions or behaviors. Functional Requirements are necessary for software engineers to execute. Non-Functional Requirements are aimed for, but not always met by engineers.
Non-Functional Requirements in Software Engineering Highlights
Listed below are the need-to-know details about the Non-Functional Requirements in software engineering. The highlights are as follows:
What are Non-Functional Requirements in Software Engineering?
Non-Functional Requirements in software engineering are those needs that are not related to specific functions, tasks or behaviors. These requirements help define specifications that systems should have to perform better. In simple words, Non-Functional Requirements help define how a system should run and behave instead of defining what a system should do.
Non-Functional Requirements in software engineering help specify needs such as security, performance and maintainability that systems should adhere to. Non-Functional Requirements help ensure that systems meet a certain standard of quality along with having useful Functions. They also help in systems being easier to maintain by engineers and easier for users to use.
How Non-Functional Requirements Are Found?
Listed below are some methods engineers use to help determine what Non-Functional Requirements are needed for their software:
Market Research: Conducting proper market research can help software engineers understand and find their Non-Functional Requirements.
Surveying: Engineers take surveys to help find out what users expect and want out of their software. Helps engineers reach a wider audience.
Interviews: Engineers conduct interviews with users and clients alike to understand their expectations from system software.
Types of Non-Functional Requirements in Software Engineering
There are several types of Non-Functional Requirements or NFRs in software engineering. Listed below is an overview of some of the types of the Non-Functional Requirements in systems. The types of Non-Functional Requirements in software engineering are as follows:
Non-Functional Requirement Type
Details
Performance
Performance Requirements help define how the overall systems should perform and behave. This includes helping in the definition of how resources are used, response times and frames. Performance Requirements help in defining how systems can run optimally.
Scalability
Scalability Requirements define how systems should operate even with a larger scale of users. It ensures that systems can handle a high volume of users without facing problems.
Security
Security Requirements help ensure the complete protection of systems. This includes protecting systems from unauthorized access, data breaches, hacks and cyber attacks. This is a top priority for systems to protect the privacy and details of users.
Some security measures that are installed to ensure security in systems include data encryption, 2-step verification and other authentication methods.
Maintainability
Maintainability Requirements help ensure that systems and software are easy to maintain by engineers. This makes it easier for software engineers to address problems, fix mistakes and correct bugs. Maintainability also helps in the addition of new features to the software.
Availability
Availability Requirements basically ensure that systems are available to users and engineers alike. Systems should be ready to use whenever users require without experiencing many crashes or other problems.
Usability
Usability Requirements ensure that systems are user-friendly and convenient to use. This means that systems have simple -to-understand interfaces that are easy to use.
Reliability
Reliability Requirements ensure that software must be good enough to be re-used by users. This also ensures that the software is consistently performing well.
Portability
Portability makes sure that systems are adaptable enough to be used in a variety of different environments by users.
Examples of Non-Functional Requirements in Software Engineering
Listed below are some examples of the different types of Non-Functional Requirements in software engineering. The examples of NFRs are as follows:
Example
Details
Availability
System servers should be online 24/7 unless under maintenance.
Security
Systems must have security questions and 2-factor verification in place before allowing users to login.
Scalability
A minimum of 50,000 users can use the system without any performance problems or crashes.
Performance
The system should take a maximum of 10 seconds to respond to a user’s input.
Non-Functional Requirements in Software Engineering: Benefits and Challenges
With Non-Functional Requirements in software engineering, there are a number of benefits and challenges that come to engineers. Provided below are some of the benefits and challenges that come to engineers with Non-Functional Requirements.
Benefits of Non-Functional Requirements in Software Engineering
The benefits of Non-Functional Requirements in software engineering are as follows:
Benefits
Details
Better Scalability
Non-Functional Requirements help define the sense of scale that systems are expected to work under. Engineers can work to make sure that systems can handle a specified minimum number of users and adapt to any growth.
User Satisfaction
By ensuring that systems are easier to use, Non-Functional Requirements help in users being more satisfied with the designed system software.
Less Workload
If planned properly, engineers can have a significantly reduced workload. If all Non-Functional Requirements are met and addressed earlier in development, software engineers have a lesser workload.
Easier Maintenance
When defining the Non-Functional Requirements for a system, engineers can ensure that the software is easier to run tests on and maintain.
Risk Reduction
By addressing important concerns such as security, software engineers can help reduce risks from threats such as cyber attacks and data breaches.
Challenges of Non-Functional Requirements in Software Engineering
The challenges to specifying Non-Functional Requirements faced by engineers are as follows:
Challenges
Details
Difficult to Implement
A lot of testing with trial and error is required to properly implement Non-Functional requirements. A significant amount of knowledge is required to work on and implement complicated requirements such as security and scalability.
Higher Development Costs
Finding, analyzing and properly implementing Non-Functional Requirements can be a very costly process. The entire process requires a significant amount of manpower, resources and tools that can add to the developmental costs.
Prioritization
It can be difficult for software engineers to prioritize which Non-Functional Requirement to work on over another. This can make certain NFRs compete for development time and resources.
Predicting Future Needs
The Non-Functional Requirements that are needed at one point may change later on. This causes software developers to put in extra work that they may have not been prepared for.
If the requirements are not properly found during the initial stages of development, it could also negatively affect the development process and hamper the overall system. Requirements may also change during the course of a project as well.
Time-Consuming
While Non-Functional Requirements can help streamline the software development process, it can also slow it down. Identifying each Non-Functional Requirement can be very time-consuming for software engineers.
What are Functional Requirements in Software Engineering?
Before going into differences, it is important to understand what exactly Functional Requirements are in software engineering. Functional Requirements are those requirements that specify what exact actions a system must be capable of. These actions are specific steps that system software should be able to do. Functional Requirements include specific behaviors, inputs, outputs or processes that system software should be capable of doing.
In simple words, Functional Requirements describe what actions a system software should be capable of. It is more aligned with the actions that software should be able to do instead of how a system should perform.
Examples of Functional Requirements in Software Engineering
Provided below is a brief overview of some examples of Functional Requirements in software engineering:
Example
Details
User Logging In
The Functional Requirement is that a user has to input their username and password to be able to login to use their account.
Browsing a Menu
Being able to view a food menu on a restaurant site is the Functional Requirement.
Notifications
The Functional Requirement is receiving a notification of a completed transfer on a banking application.
Differences between Non-Functional and Functional Requirements in Software Engineering
There are several differences between Non-Functional and Functional Requirements in software engineering. The table below provides an in-depth overview of the differences between the requirements of software engineers.
The differences between Non-Functional and Functional Requirements in software engineering are as follows:
Non-Functional Requirements
Functional Requirements
Non-Functional Requirements define how a system should function. It helps define what standards a system must meet.
Functional Requirements define what specific tasks a system should be capable of. It focuses on specific actions or behaviors of a system.
Non-Functional Requirements focus more on a software’s performance.
Functional Requirements focus more on what tasks a software can do.
While engineers aim to meet Non-Functional Requirements, it is not compulsory.
It is absolutely necessary for software engineers to meet Functional Requirements.
Non-Functional Requirements are specified by software developers.
Functional Requirements are defined by user needs and wants.
Non-Functional Requirements are significantly more difficult to test and implement by software developers.
Functional Requirements are relatively simpler to test, fix and implement for software developers.
Non-Functional Requirements are tested through methods such as Load Testing, Scalability Testing and Reliability Testing.
Functional Requirements are tested through methods such as System Testing, API Testing and Integration Testing.
These requirements are also more difficult to measure by engineers.
These types of requirements are easier to measure and keep track off by software engineers.
An emphasis is placed for a better user-experience under Non-Functional Requirements.
A lot more emphasis is placed on what a user can do with the software itself under Functional Requirements.
Best Practices for Non-Functional Requirements in Software Engineering
Provided below are some of the best practices for Non-Functional Requirements taken by software engineers:
Practices
Details
Prioritize Requirements
To avoid competition and confusion, it is a better practice for software engineers to have well-defined priorities of which Non-Functional Requirements to meet first.
Alignment with Overall Business Goals
Aligning Non-Functional Requirements with overall business goals helps engineers achieve and meet these requirements.
Research
Conducting well-thought market research helps engineers properly define Non-Functional Requirements. Software Engineers can also use methods such as surveying and interviews to find requirements.
Frequently Asked Questions
What is a Non-Functional Requirement in software engineering?
A Non-Functional Requirement in software engineering are specifications that define how a system software should operate in contrast to what a system can do.
What are the 4 types of Non-Functional Requirements?
While there are many, the 4 main types of Non-Functional Requirements in software engineering are Performance, Scalability, Usability and Security.
What is an example of a Non-Functional Requirement?
One example of a Non-Functional Requirement in software engineering is having a software be available for users 24/7 unless it needs to go offline for maintenance.
What are some of the benefits of Non-Functional Requirements in software engineering?
Some of the benefits of Non-Functional Requirements in software engineering include engineers having a lesser workload, being easier to maintain and having lesser risk.
What is the difference between Functional and Non-Functional Requirements in software engineering?
There are several differences between Functional and Non-Functional Requirements in software engineering. However, the main difference is that Functional Requirements focus more on what tasks a system can do while Non-Functional Requirements focus on the overall performance of a system.
What are the challenges of Non-Functional Requirements in software engineering?
The main challenges of Non-Functional Requirements in software engineering are that it has a higher cost and is more difficult to implement for engineers.
