Software Requirements Specification: How to Work With It

On a beautiful day, an idea popped into your head: it's time to create your product, a fundamentally new platform, or a mobile app. What’s left is just to convey this brilliant idea to the developers. 

In a text or voice message, they won’t understand the idea. Moreover, they won’t understand the project’s desired structure, functions or goals. For your vision to become a technical task for developers, you need a software requirements specification.

Defining the software requirements specification 

This document, SRS, is the basis of any software idea. And the more interested parties, investors, co-owners, and employees there are in this project, the more important this document is. 

All the people who have something to do with the project or its idea should understand it. If you have a large team, you won’t tell about your plans once. Different departments, directors, investors will have additional questions that you will answer repeatedly. The software requirements specification saves you from this. Now all the most crucial information about the idea is stored in one place.

Why is SRS needed, and why is it so important?

It provides basic information about the product, its functionality, idea, estimated costs. 

Why are all developers excited about having a specification? 

• There is no need to explain to each specialist what the project is about — he can read the SRS;

• if there is a misunderstanding between the backend and the frontend during the work, it can be resolved with the documentation;

• get additional points from investors and managers for writing such a detailed plan;

• the ability to analyze, evaluate the theoretical and actual state of the software;

• fewer edits due to universal understanding of the idea;

• product development time is shortened because everyone knows what needs to be done;

• the final product will meet the customer's wishes;

• it is possible to define the time and budget of software development clearly;

• designers immediately see what is required of them in UI/UX just by looking at the SRS;

• testers receive practical instructions on what they need to check.

The most crucial advantage is the ability to explain to the whole team what to do and compare "before" and "after.”

Writing a software requirements specification

It is written before the start of the software development process. This can be done by anyone who speaks the programmer’s language and knows how to convey a thought competently. 

If the client's company has a project manager or technical manager, they make up the SRS. Often in practice, the software development company itself makes SRS. They do this during discussions with clients. A specialist from an outsourcing company understands what the client wants and creates the document. 

After writing the SRS, it is possible to estimate the project’s time and budget.

What is inside the software requirements specification

The SRS documentation consists of several main items, including:

1. purpose and scope of the software;

2. description from the point of view of the user and the developer;

3. performance of the idea;

4. functional and non-functional requirements;

5. the prescribed software interaction with other platforms, products, and equipment;

6. restrictions in which the software will work.

This is a necessary minimum for this kind of document. Of course, you can add many more items there, but these are the key ones.

How to write SRS: step-by-step instructions

This document is fundamental and comprehensive. And this means that it's not so easy to start writing it. Where to start if there are a lot of thoughts in your head, but there is no structure? Use a step-by-step plan.

Write down the plan in chapters with details you need to disclose. We wrote about them above; they are presented in the necessary sequence. However, if you want to use a ready-made template, there are many good examples available on the Internet.

Let's get started!

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Introduction and purpose

Usually, articles suggest starting with the first specification point, the introduction. I think it's complicated, because you will need to describe the overall picture of the project, and it is challenging to do this at first. Therefore, I advise you to set this item aside until the entire document has already been written. This way, it will be a lot easier and more precise for you to write the introduction. 

Any development begins with a goal — so you should write the purpose of the software.

• Why is this product needed on the market? 

• What needs will it cover? 

• Who will it help, and how? 

• What is the scope of the software? 

• What is the value of this solution for consumers? 

• What problem with the software will be a malfunction (if this happens, then a failure has occurred)?

These fundamental questions will help you accurately describe the purpose of the project.

Description of the product operation

In this part, you need to answer one question: 

What exactly should this product do? 

So, you need to describe all the requirements for the functionality. Suppose this is a mobile food delivery application. In that case, it should have a database of restaurants, the menu of each of them, the ability to add items to the basket, pay for the order, and call a courier home. 

“The function of viewing where the courier is located is very well done in this app.” If you have information or a reference for an idea, feel free to add it. Also, write down whether integration with other software is needed and what form this integration will be.

Functional and non-functional requirements

This part is considered more technical. If you aren’t well-versed in these subtleties of creating a product, ask for help from consultants, developers, or technical directors. 

In the requirements, focus on: 

• software business logic;

• what should be the interface;

• hardware requirements for software;

• working with other systems;

• data storage, rules for collecting and deleting information in the system.

This is an essential part of SRS for developers; they will create a product thanks to this information.

What's the difference?

Functional requirements are how the system will work, and react to the action performed by the user. Everything related to data collection, calculations, business processes is included in the functional requirements. 

Non-functional requirements are a description of how the system will fulfill functional requirements. This item is more important for the user experience, as it affects the software’s speed, convenience, security, and performance.

Software usage scenarios 

The script is written in a story for at least three users. 

To begin with, you should describe each type of user as in a marketing study — gender, age, occupation, education, ability to use similar software. Next, write down a variant of interaction with the future product for each type. Also, don’t forget to describe how the software reacts to user actions. This will be a representation of functional requirements for developers.

Additional information

Also, there is a section with what isn’t included in any part of the specification. Additional information is an explanation of terms, suggestions, references, examples.

Present SRS documentation and get approval

If you need to present the project to management and investors, you must present the specification. This is often done in a presentation that will tell you in a few words about the main points. It can be either approved or requested to be completed. As soon as the document is approved, you can start developing it.

If you want to write an SRS that meets all the requirements, you can use this template.

What is a good SRS

The software requirements specification must meet some criteria. 

1. Simplicity. The document must be written in clear language. There shouldn’t be a single sentence that can be interpreted in two ways. 

2. Measurable requirements. This is necessary to analyze and evaluate the work done at the end of the software creation. 

3. Accuracy. SRS should have a piece of complete information so that specialists don’t have to ask about the small details of the project. 

4. Realistic requirements. The craziest idea may come to mind, but software developers won’t implement it. Therefore, write down a plan that can be implemented with the available budget and deadlines. 

5. Flexibility. Technologies may change, and the requirements of other platforms too. Therefore, your plan must have a possibility for maneuver and change. 

6. The logic of presentation. The sections shouldn’t conflict; the requirements should correspond to everything else. The conditions must match each other.

If the software requirements specification meets the requirements described above, you have done an excellent job. However, don’t worry if experts ask you to refine the document, it will only improve the SRS.

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Conclusion

SRS is a vital part of the development of any product. Its presence will simplify the work and give you complete software maintenance. Also, with this document, your chances of attracting investment in the project significantly increase.

Our Technorely team has repeatedly prepared complete and high-quality SRS documentation for various developments. One of our clients, for whom we specified, was BigTaurus. Contact us if you need help compiling an SRS that meets all the requirements.