Writing requirements for software development is definitely a hard challenge. However, that’s an important step and if you decide to leave it out – be sure to have troubles on the project later.
In this article, we’ll try to explain why software development specification is so important and why you should devote effort to it.
What is a Software Requirements Specification (SRS)?
An SRS is a document which defines the business objectives and software functionality. As it defines the way software should function according to the user’s or business’ requirements, knowing how to make SRS of a project is of paramount importance. However, an SRS document includes not only functional requirements but also non-functional, which are UI design, performance and security. To cut a long story short, this document is a guidance for all the developers, testers and other team members at every stage of designing and developing the software. In other words, knowing what a conventional SRS document should include is obligatory.
Reasons for Making an SRS Document
Initially, the SRS documents are created to specify future app goals and how much work is to be done by the software services provider. So a detailed outline allows the developers to realize how they can implement and built the software. Afterwards, the spec helps you to verify the software which they developed and check if it has all the necessary features implemented. Drafting a good SRS document is what you should begin with even before the development itself. There might be cases when the software created doesn’t satisfy the necessary requirements, and there the spec comes into play, as it’s the source for reference for the developers, and after studying the SRS they can continue working on the software to meet the existing requirements.
Thus, creating a top-notch technical specification is the first most important step on any project, and that has to be understood both by those responsible for software development and by the software owners. The SRS document guides the team as they design and develop the software. So, if you provide a full and unambiguous spec then there’s a big chance for you to devote less time or maybe even no time to fixing, redefining and reimplementing your software. The earlier the problem is discovered the more efficiently you can allocate the time as updating a spec before you start the development is simpler rather than the functionality which already exists. Usually, a technical spec is the result of the first conversation of the customer and the development team, because it is used for reference for estimating time and costs of the project. And as initially an SRS document is meant to provide a detailed outline of the upcoming software, it’s much faster and easier to conduct the precise estimation of the project.
Plus, as building an app is an ongoing process, the people on the project change almost all the time. So when the project is being handed over to another part of the team, the specification will be absolutely indispensable. Isn’t it a good reason for sitting down and making an SRS?
A high-level spec also means that it’ll be easier to update the software product. The SRS has to be updated every time there’s a modification and in this very case, all the members should be engaged in the reconsideration of the future changes.
So as we said before, making an SRS document of high quality is totally a must.
How Do I Write a Good SRS document? Here we’ll talk about the main rules one should follow while writing a spec.
1. Only one person should write the spec. Of course, there are a lot of members on the team who contribute their incredible thoughts to this document, however, it should be only one person who will bring together all ideas into a solid proposal.
2. SRS is not a kind of manual. Of course, an SRS contains something which doesn’t exist yet, however, this doesn’t imply that you have to describe every single detail. Don’t dive deeply in all the little things, include only those that are really significant.
3. Don’t make your writing sound dull. When you understand that the information you wrote is boring, then there’s little chance that someone else will be happy to read it.
4. Don’t try to finish it at all costs. It’s perfectly fine if you brush aside in some parts like TBD. If you just inform the readers that this is what’s to be done and make sure that you finished all the thoughts before the go-live.
5. Bear in mind that there won’t be any second version. Some people make a common mistake when they start thinking that there’s a chance of proposing a short-term solution as there will be a rewrite soon. Unfortunately, it’s very unlikely as the systems are seldom substituted, they are usually just being fixed and expanded as time goes by. You can call out some components and processes which might be subsequently enhanced, however, don’t forget that the main design decisions will last for long.
How to Write an SRS Document Step by Step?
They say that well begun is half done, so if you write a nice introduction then you’ll be halfway to success. Firstly, you have to define your product target. The introduction gives a summary of the whole document, it specifies the project idea, and it’s a significant component of the software spec.
Before you start building the app, you have to be aware of the market situation in the niche which you are planning to occupy, plus don’t forget to research the competition level, because different factors including the above mentioned can affect the requirements. Your readers are likely to be the present and future experts dealing with your tasks and they do need to understand the enterprise environment. When the business context is evident you can define the top priorities and arrange the software development process.
Another point to be mostly listed in the introduction section is the amount of work on the upcoming project. Here you are to talk about the product specs: its benefits, unique features, aims and so on. It’s essential to make an accurate project estimation and to make a cooperation with your services supplier productive.
Another crucial point to be mentioned in the introduction is your target audience: who is to be using this software, what their expectations and preferences are. A nice idea would be to think about limited access for some clusters of users, the devices your users will be using and their location.
If you want to, you can also include the abbreviations and definitions section in order to avoid confusion, so that’s totally up to you. Usually, it serves the developers a good job when the app is meant for a particular field like Healthcare or Automotive.
2. A General Outline of the System
Remember: when you write, your basic principle should be the general-to-specific principle. So before you jump straight to the tech spec of the product, you definitely need to provide its general overview. A great start is to mention if that some new app or a current app which needs changes.
Afterwards, main interfaces and structure elements should be mentioned, feel free to use visual content to support your words and help your readers.
Then you can switch to the modes and states of the upcoming system, general requirements, what it should be able to do and what are its limitations, there’s no need for a thorough description here as you’ll come back to this point later in your document.
Be sure to include conjectures and dependencies (the elements which might impact the fact of how relevant this variant of SRS is). You should mention them to reduce potential hazards. Last but not least is operational scenarios, which means how the elements of the system are engaged with each other, with the environment and with the user. A good way to show their interaction is to create a chain of events which occur with the user.
3. System Capabilities, Conditions and Constraints
This part is of utmost importance, so be sure to outline the elements here thoroughly, as it’s the section which helps developers, designers and other team members grasp your ideas and requirements.
Here we describe the requirements which can be subdivided into two groups: non-functional and functional. The first can be quite similar for a range of industries. They outline the system performance and the major component here is the business requirements document that contains the anticipations and needs of the final users.
The second type of requirements describes the system's behavior, in other words, what it is expected to do in various cases.
Then go the logical data requirements. In case you have troubles writing this part, think over the data processing within the system, its type, the way its arranged and linked. Making up a visual model is just a great way out.
4. System Interfaces
There are such types of interfaces as internal and external interfaces. Here you are to clarify the way the system components (existing, on the implementation stage and future) are interdependent. Remember to take into consideration both the people who will be using your system as well as other apps which should be working with the system.
RTM (Requirements Traceability Matrix) is a special instrument which allows you to check that all the requirements for testing are satisfied. This section of the SRS guarantees that the process of development is smooth. The Requirements Traceability Matrix itself is a table which contains all the items from the technical document and requests for changes.
The way this document looks like depends on the company which makes it.
Don’t forget to include this section, though it might seem a little strange to provide references. It’s very simple: just add the links to all the necessary documents, to their dates, authors plus your own comments.
7. Other Optional Sections
The sections which you also might need in your SRS document are:
1) Glossary (in case you have too many acronyms, to put them all into “Introduction”);
2) Revision history (if your project continues for quite a long time, then it’s likely that there will be a couple of SRS document versions, so you might want to put all the versions into a single table);
3) Appendices (in case there’s information you didn’t manage to include into other sections, you can put it into appendices).
As soon as you decide to start your software development (website, mobile app, etc.), be sure that your first step is to make an SRS of high-quality. Your spec should be written for the benefit of the future customers of your software and the software development team, so the SRS needs to be clear and accurate. Devoting time and effort to make up a nice spec will result in building the software which your customer needs and expects.
In case you feel troubles while writing your own SRS, reach out to us and we’ll be glad to assist.