How to Write a Software Requirements Document (SRD)

Crafting a Software Requirements Document (SRD) is a critical step in the software development lifecycle, serving as a blueprint for both the development team and stakeholders.

What is SRS or SRD? A software requirements document (SRD) outlines the functions and performance standards for the software. It also outlines the features the product must have to satisfy the demands of all stakeholders (business, users).

This document ensures that everyone involved has a clear understanding of the project objectives, functionalities, and constraints, thereby minimizing misunderstandings and maximizing project success.

Our guide to “how to write an SRD document” is founded on best practices and implemented into the design of our bespoke requirements gathering tool, which you can access here:

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In this blog post, we will guide you through the essential components of an SRD, from defining your project vision and scope to detailing specific functional and non-functional requirements. Whether you’re a seasoned project manager, a software developer, or a stakeholder looking to refine your project’s direction, this comprehensive guide will equip you with the knowledge and tools needed to write an effective Software Requirements Document. Join us as we break down the complexities of SRD writing into manageable steps, ensuring your next project is built on a foundation of clarity and precision.

What is a Software requirement specification document?

A software requirement specifications document outlines the intended actions and performance criteria of the software. Additionally, it delineates the essential functionalities necessary to meet the stakeholder requirements specifications, including businesses and users.

Why Use an SRS Document for Software Requirements?

In a software requirements specification document you want to define the goal of what you are building, discuss what you are creating, detail each individual software requirement, and deliver it for approval. A proper requirements document will outline every detail, including the expectations for connecting to other software and how software will interact when embedded in hardware. Real-world users and interpersonal communication should be taken into account when creating a SRS report.

An in-depth SRD offers a single point of truth that the development team will rely on. It serves as your strategy and maintains communication across all of your teams, including development, testing, and maintenance.

EXAMPLE OF WHEN A SOFTWARE REQUIREMENTS DOCUMENT IS REQUIRED:

Imagine you’re a business analyst leading a project to develop a state-of-the-art e-commerce platform. The success of the project relies heavily on a well-crafted software requirements document. To ensure clarity and precision, you gather your development team, QA testers, and stakeholders for a requirements workshop.

A great example of a Requirements Document – software requirements document example

However, an alternative to requirements workshops can be using a software requirements gathering tool. In this scenario, you employ robust software that facilitates collaborative requirements gathering and documentation, like the one here. This tool allows team members to input and review requirements in real-time, making it accessible to remote team members and accommodating different time zones.

In the workshop or through the tool, you systematically break down the requirements into functional, non-functional, and technical specifications. You discuss user stories, use cases, and system diagrams to create a visual representation of the system’s behavior. You also detail performance, security, and scalability requirements to address non-functional aspects.

As you document these requirements, you make sure they are clear, unambiguous, and testable. Each requirement specifies who needs it, what it entails, and why it is essential. You also include acceptance criteria to measure when a requirement is met.

Your well-structured software requirements specification document, whether derived from the workshop or the requirements gathering tool, serves as a single source of truth for everyone involved in the project. Developers have a clear roadmap, testers can create effective test cases, and stakeholders understand what to expect. Changes are managed through a formal process to avoid scope creep.

This approach, utilizing a requirements gathering tool, results in a successful project, delivered on time and within budget, meeting not only the stakeholders’ expectations but also exceeding end-users’ satisfaction. It’s a testament to the importance of a well-written software requirements document, whether created through workshops or tools, in guiding a project to success.

In this scenario, the key takeaway is that investing time and effort in writing a comprehensive software requirements document, facilitated by requirements gathering tools if necessary, pays off by ensuring everyone involved understands what needs to be built and why, leading to a successful project outcome.

What Should a Software Requirements Specification Document Include?

9 Steps to Writing Software Requirements Specifications (SRS document):

  1. Introduction: An overview of the document’s purpose and scope.
  2. Overall Description: A high-level view of the software, including its objectives and the problems it aims to solve.
  3. Customers: Details about the intended users and stakeholders of the software.
  4. Functionality: A comprehensive breakdown of the software’s features, functions, and capabilities.
  5. Platform: Information about the technology stack, hardware, user interface
    and software platforms on which the software will operate.
  6. Development Responsibilities: Roles and responsibilities of the development team, including project managers, developers, and testers.
  7. User Class and Characteristics: A description of the user groups and their specific requirements.
  8. System Features and Requirements: The heart of the document, outlining both functional and non-functional requirements in detail.
  9. Common Mistakes to Avoid: A section highlighting common pitfalls to steer clear of when creating an SRS.

Each section plays a vital role in ensuring the project’s success, and together, they create a comprehensive roadmap for the software development journey.

The key differences: Functional vs Non-Functional Requirements

Defining the “What” and the “How”

In an SRS document, it’s crucial to distinguish between two primary types of requirements: functional and non-functional.

  1. Functional Requirements: These describe the specific features and functionalities the software must possess. Functional requirements answer the question, “What should the software do?” They define the behavior of the software when certain actions or inputs occur. For example, in an e-commerce application, a functional requirement might specify that users should be able to add products to their shopping carts.
  2. Non-functional Requirements: Non-functional requirements focus on “how” the software should perform, rather than “what” it should do. They encompass aspects like performance, security, usability, and reliability. Non-functional requirements define the system’s qualities and constraints. For instance, a non-functional requirement could dictate that the e-commerce platform must load product pages in under two seconds.

By clearly defining both functional and non-functional requirements, an SRS provides a holistic view of the software’s capabilities and performance criteria.

Identify the stakeholders (Gather as much detail)

Identifying stakeholders when writing software requirements specification for an SRD is an important step in the process. Stakeholders are individuals or groups who have an interest or concern in the software being developed. Some examples of stakeholders include:

It is important to identify all stakeholders and to consider their needs and requirements when writing the SRD. This will help ensure that the software meets the needs system requirements of all stakeholders and is successful.

Product scope: Define the scope with a detailed description

Defining the scope when writing an SRD is an important step in the process because it helps the software requirements specifications establish the boundaries of the software and what it will and will not do. The scope should be specific, measurable, and achievable, and should include a description of the following:

Clearly defining external interface requirements and the scope in the SRD, will help to ensure that the software is developed to meet the needs of the stakeholders and that the project stays on track and within budget.

Gather requirements

Gathering requirements is an important step when writing software requirement specification for an SRD because it helps to ensure that the software meets the needs of the stakeholders. There are several techniques that can be used to gather requirements, including:

It is important to gather requirements from all stakeholders, including the end user, users, customers, and the development team, to ensure that the software meets the needs of everyone involved. It is also important to document all requirements in a clear, concise, and verifiable manner, to avoid any confusion.

However, the most effective and efficient way of gathering requirements is using software, read more in our blog ‘Why You Should Use Software for the Requirements Gathering Process.’

Alternative Options: Software Requirements Specification Automation

While traditionally SRS documents have been created manually, SRS automation tools offer a more efficient and effective option for generating, managing, and maintaining these critical documents. These tools streamline the process, reduce the risk of errors, and enhance collaboration among project stakeholders. By automating the SRS creation process, and utilizing existing software requirement specification templates, organizations can save time, reduce costs, and improve the overall quality of their software development projects.

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Review and Validate Software Requirements Specifications

Reviewing and validating an SRD is an important step in the process to ensure that all software requirements documents are complete, consistent, and verifiable. The following steps can be taken to review and validate an SRD:

It is important to review and validate the SRD before the software development begins, so that any issues can be identified and resolved early in the process. This will help to ensure that the the software product meets the needs of the stakeholders and is developed on time and within budget.

Update and Maintain Software Requirements Specification Document

Updating and maintaining an SRD is an important step in the software development process to keep software requirement documents ensure that the software meets the evolving needs of the stakeholders and to keep track of changes made to the software. The following steps can be taken to update and maintain an SRD:

It is important to update and maintain the SRD throughout the software development process to ensure that the software meets the evolving needs of the stakeholders, and to keep track of the changes made to the software. This will help to ensure that the software is developed on time and within budget, and that it meets the needs functional requirements of all stakeholders.

Software Use Cases in an SRS: How to Write

Bridging the Gap Between Requirements and Implementation

Use cases are a vital part of an SRS document as they help in understanding how users will interact with the software. They bridge the gap between high-level requirements and the actual implementation. When writing software use cases, consider the following:

  1. Identify Actors: Define the different actors or users who will interact with the software. For instance, in a banking application, actors could be customers, tellers, and administrators.
  2. Describe Use Cases: Detail the various actions or tasks that actors can perform within the software. For example, a customer can log in, check their balance, transfer funds, and so on.
  3. Specify Scenarios: Provide specific scenarios or steps for each use case, outlining what happens when an actor interacts with the software. Use clear and concise language to describe the expected behavior.

By including software use cases in your SRS, you ensure that everyone involved in the project has a clear understanding of how the software will function in real-world scenarios.

What are the key characteristics of Software requirement specifications in engineering?

The Hallmarks of a Successful SRS

A great SRS in software engineering possesses the following characteristics:

  1. Explicit: The requirements are clear and unambiguous, leaving no room for interpretation or miscommunication.
  2. Measurable: Requirements should be quantifiable, allowing for testing and validation.
  3. Complete: The document covers all necessary aspects of the project, leaving no critical requirements or features unaddressed.
  4. Viable: Requirements should be achievable within the project’s constraints, including budget and timeline.
  5. Flexible : Requirements should allow for some degree of flexibility to accommodate changes that may arise during the project’s development.
  6. Verifiable: Each requirement must be testable, so it’s possible to confirm that the software meets the specified criteria.
  7. Consistent: The requirements within the SRS should not contradict one another, and terminology should be used consistently throughout the document.
  8. No Implementation Constraints: Avoid prescribing specific implementation details in the SRS. Focus on what the software should do rather than how it should be done.
  9. Accurate: Ensure that all information in the document is up-to-date and correct. Any inaccuracies can lead to misunderstandings and delays.

A well-crafted SRS exhibits these characteristics, setting the stage for a successful software development project.

An Example of Software Requirement Specification

To better illustrate the principles discussed, let’s provide a brief example of an SRS structure:

Introduction

The introduction provides a concise overview of the document’s purpose and scope, explaining its importance and how it serves as a reference for all stakeholders involved in the project.

Project Description

In this section, we describe the software project, outlining its objectives, the problems it intends to solve, and the expected outcomes. It’s essential to create a compelling narrative that clarifies the project’s context.

Who are the Customer’s

Detail who the intended users and stakeholders are, their needs, and how they will benefit from the software. This section establishes a clear understanding of the target audience.

Pick the right Functionality

List and describe the software’s features and functions, including specific use cases. For example, in an e-commerce application, this section would detail the features for browsing products, adding items to a shopping cart, and checking out.

Choosing a Platform

Provide technical assumptions and information about the technology stack, software platforms, external components and hardware interfaces and requirements necessary to run the software effectively. This helps in infrastructure planning.

Development Responsibilities

Outline the roles and responsibilities of the development team, defining who will be responsible for various tasks within the project. This section ensures accountability and clarity in the development process.

User Class and Characteristics

Define different user groups and their unique characteristics. For instance, in a hospital management software, user classes might include doctors, nurses, and administrative staff, each with distinct requirements.

System Features and Requirements

This is the heart of the SRS, where you detail both functional and non-functional requirements. For functional requirements, you would specify how users can schedule appointments, access patient records, or generate reports. For non-functional requirements, you might outline response time expectations, security protocols, and scalability requirements.

Common Mistakes to Avoid When Writing an SRS Document

This section highlights common pitfalls that should be avoided when creating an SRS. It may include issues like vague requirements, contradictory statements, or excessive technical jargon.

Conclusion

Creating an SRD can be a challenging and time-consuming process which is costly to a business if done poorly. Therefore, using software for the requirements gathering process can help improve the efficiency and effectiveness of the process, leading to better outcomes for the project, creating the most full and accurate SRD.

Software Requirements FAQS

What Constitutes an SRS Document and Its Significance?

An SRS (Software Requirement Specification) document is a pivotal artifact in the realm of software development, outlining the comprehensive set of requirements that drive a project. Understanding both its definition and its significance is vital for effective project management, communication, and development.

Essential Components of a Software Requirements Specification

A Software Requirements Specification (SRS) comprises various key elements that collectively define the software’s functionalities, features, and constraints. These elements serve as building blocks for precise project planning and execution.

Stakeholders Involved in Crafting a Software Requirements Specification

The creation of a Software Requirements Specification (SRS) involves a collaborative effort among several key stakeholders. Identifying the right contributors is paramount to ensure that the document accurately represents the project’s objectives and requirements.

What are considered good characteristics of SRS documents?

  1. Clarity: It should be clear, unambiguous, and easy to understand.
  2. Completeness: It must cover all necessary aspects, leaving no critical requirements or features unaddressed.
  3. Verifiability: Each requirement should be testable, allowing for validation to confirm the software system meets the specified criteria

Who prepares SRS Documents?

Software requirements specifications are typically prepared by a collaborative effort involving multiple stakeholders, including business analysts, project managers, software engineers, and subject matter experts. These experts work together to ensure that the document accurately represents the project’s objectives and requirements.

What are the key elements of a software requirements specification document?

The key elements of a Software Requirements Specification (SRS) document include:

  1. Introduction
  2. Overall Description
  3. Customers
  4. Functionality
  5. Platform
  6. Development Responsibilities
  7. User Class and Characteristics
  8. System Features and Requirements
  9. Common Mistakes to Avoid
Our product Requiment requirements gathering software, guides you through prepared questions to determine a full and detailed requirement specification and project scope based on outcomes. This application acts as a virtual business analyst, guiding users through the requirements process, whilst providing insight and recommendations to the user based on the type of application being designed as well as trends from other users. Ultimately, our mission with Requiment is to make the process of software requirements capture more accurate, agile and efficient leading to more successful projects.