How to Write Software Requirements

How to Write Software Requirements

Before any piece of software is designed, it’s essential to ensure everyone understands the product requirements. Software requirements detail the features and functions of a software application and outline the organization’s understanding of the client’s needs. These product requirements are typically written in a software requirements document or SRD.

Software requirements outline the blueprint for the scope of the software project, but they don’t include technological solutions or designs. The SRD will include information about what the end-user will be able to do with the software and details about security, user interface, and data requirements.

How to write product requirements

The end product’s success relies on getting the software requirements right from the start, so you’ll need to know how to write product requirements. Software requirements need to be: 

Complete and correct:
Software requirements should be fully outlined so the product delivered meets all the goals of the client or end-user. Therefore, the software requirements should be written as completely and accurately as possible.

Clear and unambiguous:
Software requirements should not leave anything up to interpretation by the end-user or client. Every element of the SRD needs to be clearly written so it can be understood by all stakeholders.

Testable and measurable:
Software requirements included in the SRD should be able to be tested and measured and include quantifiable metrics where possible. 

Verifiable and traceable:
When the designers or engineers begin creating solutions for each requirement, they need to test each element and connect it to a product requirement. To this end, you should ensure each requirement has a specific code or number attached for easy traceability. 

Consistent:
Software requirements shouldn’t conflict with each other throughout the document but instead be consistent throughout. Similarly, software requirements should not include duplication within the document. 

Each outlined specifically:
Resist the temptation to lump more than one requirement in together. This makes testing and tracing very difficult in the long run. 

Types of product requirements to include

When determining how to write product requirements, you’ll need to include a selection of different categories. The following is a list of some of the types of requirements to include:

• Functional requirements outline what the software needs to accomplish 
• User interface requirements can include user menu options, as well as warnings or operator messages 
• Capability requirements will include specific performance information and any computing environment limitations (like memory size) that a user should note 
• Software inputs and outputs and data requirements will involve determining what type of data ranges will be required, as well as data storage information 
• Security requirements will include data protection, user authentication, and user authorization 

The process by which software companies gather information to fill out the software requirements includes four steps: elicitation, analysis, specification, and validation.

1. Elicitation: The first step in how to write software requirements is gathering information and data from stakeholders. This information can be collected via interviews, data analysis, or focus groups. 
2. Analysis: Once information has been gathered, the team needs to analyze the data and determine priorities for the various requirements using stakeholder information. 
3. Specification: After the requirements information has been gathered and analyzed, specific case studies, visual analysis models, user stories, and functional requirements are compiled and organized to give a broader picture of what will be required. 
4. Validation: Finally, requirements validation involves checking to make sure the requirements you’ve outlined are going to result in what the client or end-user actually wants. It’s important to run checks for completeness, consistency, validity, realism, ambiguity, and verifiability to flush out any problems before software development begins.

Software requirements have an enormous impact on the product developed by engineers, so ensuring you know how to write product requirements before you embark on the process is vital.