Anyone who’s ever experienced the fun of passing the military training knows how to properly make a bed. In fact, soldiers are TRAINED to make a bunk. Blankets should make a 45-degree angle at the corners and be rolled back to show off snow-white sheets, linens have to be pulled tight under the mattress, pillowcases should always stay crisp…But why are people in the military so bothered with little things? The answer is quite simple: little things help to make big things happen. By completing such small tasks, soldiers learn how to perform other, more important duties according to standards.
In software engineering, project managers are preoccupied with writing non-functional requirements (NFRs), just like soldiers when making their beds. While the client focuses mainly on product features, it’s managers’ task to make sure that the solution will meet quality and performance benchmarks.
If you want your software to function as expected, you must have NFRs in place. So keep reading this article, as the JatApp team will give you examples of NFRs, uncover their benefits, and show you how to build them with ease. Ready? Let’s jump right in.
Thinking beyond features: What are the main types of non-functional requirements?
Non-functional requirements or simply NFRs refer to specifications that outline the system’s quality attributes and limitations. NFRs set specific standards that a product must meet before it can be released to the market.
Most teams make mistakes when they handle only one or two obvious requirements and disregard the rest. An effective project manager pays close attention to all NFRs during the development phase.
Let’s take a look at the main types of software requirements you should focus on in your project:
These requirements describe how fast a solution or its component responds to users’ actions. In other words, it outlines how long a user should wait until they can complete a task, like process a transaction or load a new page.
Example: The search feature must provide results within four seconds for up to 8,000 items in the database, allowing users to view no more than 50 results per page. These results must be sorted by relevance and show the top 50 most relevant items on the first page.
The scalability non-functional requirements evaluate the highest workload, under which software will still function as described in the performance requirement.
Example: The solution must be scalable enough to support 2,000,000 users while showing optimal performance.
The portability non-functional requirements determine how easily software should be installed and run on different platforms.
Example: The solution must be portable across macOS, Windows, and Linux. No modifications to the code are needed to run on these operating systems. The product must run on 64-bit and 32-bit architectures.
Compatibility establishes how a software system can interact with another system in the same environment.
Example: The iOS app must be compatible with iPhone devices running various OS versions, including 3.6, 3.3, 3.4, and 4.3.
The maintainability requirement shows how the application must be built to make sure developers can easily change and update it over time.
Example: The application must be built using a modular architecture. Changes to one module must not impact other modules’ behavior.
The availability non-functional requirements define how likely the solution will be accessible at a certain time. The requirement can be shown as a percentage of successful requests or as a percentage of time the application is available for operation in a given time period.
Example: The solution must be available to users 24/7, with the possible downtime of 30 minutes each month for scheduled maintenance. Any unplanned downtime must take no more than 10 minutes and should happen less than once a quarter.
The usability non-functional requirements define how hard it is to use the application. At this point you may wonder how to address this requirement without being biased. Here are the usability criteria by Nielsen Norman Group, which help in this regard:
- Efficiency: How quickly can users achieve their main goals?
- Learnability: How fast can users complete tasks within your app?
- Memorability: Will users be able to quickly start working with your app after they’ve been away for a while?
- Errors: How often do users make errors?
- Satisfaction: Do users find your interface intuitive and pleasant to use?
Example: The error rate of users entering their contact information must not exceed three percent.
Localization is the requirement that defines to what extent the application is aligned with the environment of the local market. By saying environment, we mean cultures, currencies, laws, languages, and similar. A software product that meets localization criteria has more chances to woo over the target audience.
Example: the height must be presented in feet and inches.
The security non-functional requirements define how well data is protected from unauthorized access. Sometimes, security non-functional requirements can become functional ones. For example, the app can have a two-step authentication feature to ensure better security to its users. In all other cases, the security requirements are presented as encryption methods and standards that serve as a guidance for software developers.
Example: A payment gateway must have PCI DSS compliance.
How can NFRs help development teams?
As a writer, I always start writing an article with an outline. This helps me deliver my message more clearly, without getting sidetracked with irrelevant details. Just as writers rely on outlines as a roadmap to write their articles, development teams use NFRs to guide their work and achieve their goals. Let’s discuss how exactly software developers benefit from these docs.
- They shape the app architecture
Software engineers rely on NFRs to design the architecture for an application. For instance, the security requirement can necessitate that some system components must be isolated, which, in turn, might impact the app architecture.
- They provide performance goals
NFRs baseline the performance for software engineers, showing them the difference between the good and the bad. When teams have a performance goal, they’re more able to stay on track and deliver the product that functions as expected.
- They cut down time spent on fixing bugs
NFRs clearly outline how the app should function, allowing developers to get things done from the first shot. If teams have the clear goal, chances are they won’t miss bug eroding software. Plus, once they are no longer burdened by constant rework, they can manage their workload more efficiently.
What are the perks of NFRs for project managers?
Writing NFRs assists managers in many ways, from ensuring timely delivery of features to minimizing data leakage:
- Meeting project deadlines
NFRs can save the team from bug fixing, rework, and even system failure. Since managers don’t need to place extra work on developers’ shoulders, they’re more able to deliver the project on time.
- Avoiding budget overruns
In software development, time = money. Period. Less development work always means less costs spent on the project. With NFRs in place, project managers can forget about a nerve-wracking experience, when they had to bill a client for work they could easily prevent.
- Ensuring product usability
The beauty of NFRs is that managers can deliver software that meets clients’ demands without a hassle. If they omit these docs, it’s highly likely that the final product will have a messy interface and poor performance, which could result in users’ frustration and low adoption rates.
- Minimizing security risks
The security requirement is super important for ensuring data protection in your app, especially if we’re talking about fintech products. Managers that disregard those documents are giving a green light to hackers and cybercriminals.
How to document non-functional requirements
Here at JatApp, we’ve created NFRs more than 200 times and now want to share nuggets of wisdom and advice on how to develop requirements for your project.
- Set your NFRs early on
Since NFRs have a huge impact on your app architecture, it’s better to identify them early on before you get to the development pipeline. Once you get a clear understanding of your functional requirements, it’s high time to discover their non-functional counterparts. You might want to ask yourself the following questions: “How fast should the software be?”, “What could lead this development project to failure?”, “Are there any security standards in the industry?”, and so on.
- Categorize requirements
Sort out your non-functional requirements into different categories, such as performance, compatibility, maintainability, and so forth. Splitting up your requirements in different buckets will help you prioritize them and manage resources more easily.
- Provide the rationale
State the reasons behind each requirement, explaining why it’s critical to the project success. This can not only help with prioritization of your NFRs but also offer more context to your team members.
- Create NFRs for system components instead of the whole software
Just like each musical instrument needs a unique set of notes to create a melody, each system component may require specific NFRs to ensure app’s optimal performance. For example, if your users never use an admin panel, you don’t need to bother with performance limitations for this component. Otherwise, your developers would scratch their heads over problems for absolutely no reason.
- Make sure your requirements are measurable
Without concrete measurements, you may find yourself lost in a sea of cognitive biases and subjective opinions, leading to unmet user expectations and scope creep. Saying that you want your app to run fast means nothing to your team members. But what if you specify that your product must respond to 98% of requests within five seconds? Do you feel the difference?
Get peace of mind by having JatApp take care of your NFRs
Creating NFRs is often a daunting and time-consuming task, which often makes this aspect of software development overlooked. But without these documents, businesses are having a hard time trying to meet stakeholders and users’ expectations in terms of performance, quality, and usability. Today, everyone, from small startups to well-established companies, who want to stay alive in the cut throat competition, should think of NFRs as means to timely release high-quality software to the market.
The last seven years the JatApp team has been on a journey to deliver both usable and secure products. To ensure quality software, our project managers and engineers have built a habit of taking NFRs pretty seriously. We are convinced that our meticulous planning and thorough approach to building NFRs in particular has made us a top managed IT services provider and mobile app development company.
Want to spruce up your NFRs? It takes just a few clicks to reach out to us and start planning your project.