Software Engineering basics - Software Requirement Specification

Software Requirement Specification (SRS)

A Software Requirement Specification (SRS) is a detailed document that clearly and completely defines what the software will do, how it will behave, and the constraints it must follow. It is used as a formal agreement between clients and developers to guide the entire software development process.

Definition:

An SRS is a structured document that outlines the functional and non-functional requirements of a software system.

It answers:

• What the system will do?

• How users will interact with it?

• What constraints or conditions apply?

Structure of a Typical SRS Document

1. Introduction

• Purpose – Why this document exists

• Scope – Overview of what the software will do

• Definitions & Acronyms – Clarifies technical terms

• References – Related documents or standards

2. Overall Description

• Product Perspective – How this system fits in (new or part of a system)

• User Characteristics – Who will use it?

• Assumptions and Dependencies – External factors or conditions

3. Functional Requirements

These describe what the system must do.

Examples:

• The system shall allow users to log in.

• The system shall generate monthly reports.

• The system shall validate user input.

4. Non-Functional Requirements

These describe how the system performs, not what it does.

Types:

• Performance – Response time, speed

• Security – Login, data encryption

• Usability – User-friendly interface

• Scalability – Able to grow with users or data

5. System Features

Detailed explanation of the main features or modules.

6. External Interface Requirements

• User Interfaces – Screens, forms

• Hardware Interfaces – Devices, sensors

• Software Interfaces – APIs, third-party tools

• Communication Interfaces – Protocols, networks

7. Other Requirements

• Legal or regulatory constraints

• Backup and recovery

• Localization/internationalization