7 Easy Steps to Nail Your Software Requirements Specification

Identify the purpose of the SRS

The first step to drafting an SRS document is to identify its purpose. In general, an SRS should provide a software development team with a clear understanding of the system’s functional and non-functional requirements.

However, it’s a good practice to be more specific and identify exactly what the SRS will be used for and who the audience will be. Consider questions such as:

• Is the SRS intended for internal or external use?
• Is the SRS intended to act as an addendum to another document like a Scope of Work (SOW) or a Request for Proposal (RFP)?
• Who is the intended audience of the SRS?

Provide an overview of the software project

Now that you’ve identified the purpose of the SRS document, you should draft a short description of the software project. Specifically, you should include:

• Project overview: Describe your project from a high-level, including a short description of the key software components and information about each of your end user groups.
• Team members: Document a list of the roles and responsibilities of each team member, including everyone from your development teams, management, product teams, and other stakeholders.

Identify assumptions

Identifying assumptions is a key part of the SRS process. Generally speaking, assumptions are things that are taken as true, even though they have not been tested or verified. It is likely that every member of your project team is making one or more assumptions about the project.

It’s a good idea to survey all stakeholders about the project and document any assumptions they are making. This will help you to:

• Turn assumptions into system requirements that will be documented in your software requirements specification.
• Make changes to the project’s scope, delivery schedule, or budget based on the assumptions
• Align stakeholders on areas of the project that have conflicting assumptions.

Define functional requirements

Functional requirements are at the heart of software requirements specifications. They should define the specific functions that the system must perform in order to satisfy the customer’s needs.

Here are a few tips for writing effective functional requirements:

• Write in the form of user stories: User stories are typically written in the format of: As a [role], I want [feature] so that [benefit]. This allows the requirements to be written in a way that is easily understood by all stakeholders. By capturing the perspective of the end user, user stories can help to ensure that the software interfaces are designed to meet the user’s needs.
• Break requirements down: Each requirement should only cover a single, specific action that a user needs to take. Complex or multi-step actions should be split up into multiple requirements to simplify the process of writing test cases.
• Make sure they are measurable: Functional user requirements should be measurable so that you can track progress and measure success. Make sure that each requirement is quantifiable and can be tested in a meaningful way.
• Keep them simple and concise: Be sure to keep your requirements as simple and concise as possible. Use clear language and avoid jargon. A good way to achieve this is to initiate a formal peer review process of all requirements.
• Don’t include implementation strategies. Requirements should be written in terms of what the system needs to accomplish, not how it should be implemented.
• Prioritize requirements: Mapping each requirement to a priority can help the development team understand what items are most important. We recommend you use a method such as MoSCoW to sort your requirements by Must Have, Should Have, Could Have, or Won’t Have.

Define non-functional requirements

Nonfunctional requirements are just as essential in a software requirement specification document as functional requirements. Without non-functional requirements, a system may be built that does not meet the core expectations of stakeholders from a security, quality, or reliability perspective.

Work with your software engineering team to lay out requirements that address:

Define integration requirements

Rarely does a software system stand completely on its own. You may need to integrate with your existing tech stack, augment its functionality by integrating it with new tools, or even build in a certain degree of flexibility to allow for additional integrations in the future. Integration requirements should define:

• How the software should interface with other software systems
• How data should be transferred between systems
• Any specific data security requirements for integration with other software systems
• Tech stack architecture requirements

Document any open issues

The last step in the SRS process is to document any open issues related to your project. Open issues are any unresolved topics or questions that need to be addressed in order to successfully build the required software solution. These could include:

• Questions about the scope of the project
• Requirements that need to be clarified or further defined
• Discrepancies between requirements, assumptions, or other documentation that need to be addressed
• Areas that need further research or analysis before development begins

Documenting open issues is important because it will help to alert stakeholders to work that still needs to be completed. It can also be helpful to share these open issues with developers or potential software vendors so they can understand what still needs to be refined before development begins.