Subsystem Requirements

---

1. Introduction

1.1 Purpose

This document outlines the requirements for a subsystem within the larger system. The purpose is to provide a comprehensive specification that ensures the subsystem meets its intended functionality, integrates seamlessly with other system components, and adheres to performance and quality standards.

1.2 Scope

The subsystem is designed to perform specific functions within the overall system. This document includes detailed functional and non-functional requirements, interface definitions, constraints, and assumptions necessary for the subsystem’s development and integration.

1.3 Definitions and Acronyms

• Subsystem: A self-contained unit within the larger system with specific responsibilities.

• Interface: A defined point of interaction between the subsystem and other system components.

• Performance Metrics: Quantitative criteria used to evaluate the subsystem’s effectiveness, such as response time and throughput.

---

2. Functional Requirements

2.1 Overview

Functional requirements define the operations the subsystem must perform to fulfill its role within the overall system. These requirements ensure that the subsystem delivers the expected behavior and integrates properly with other system components.

2.2 Functional Requirements Table

ID	Requirement	Description	Acceptance Criteria
FR-01	User Authentication	The subsystem must authenticate users using multi-factor authentication (MFA).	User authentication succeeds in 95% of cases within 2 seconds.
FR-02	Data Processing	The subsystem must process and validate incoming data according to predefined rules.	Data processing is completed with 99% accuracy.
FR-03	Error Handling	The subsystem must handle errors by logging them and displaying user-friendly messages.	Errors are logged with timestamp and severity level.
FR-04	Report Generation	The subsystem must generate and export reports in PDF and Excel formats.	Reports are generated in under 10 seconds and formatted correctly.

2.3 Use Cases

User Login

• Actors: End User, Authentication Service

• Description: The user logs into the subsystem to access protected features.

• Preconditions: The user has valid credentials (username and password).

• Postconditions: The user is authenticated and granted access or denied based on credential validity.
  

Flow of Events:

1. The user enters a username and password into the login interface.

2. The subsystem sends credentials to the Authentication Service.

3. The Authentication Service validates credentials and returns the result.

4. If credentials are valid, the subsystem grants access and redirects the user to the dashboard; if invalid, it prompts the user to re-enter credentials.

---

3. Non-Functional Requirements

3.1 Performance

• Response Time: The subsystem must respond to user inputs within 2 seconds. For example, login requests should be processed within this timeframe.

• Throughput: The subsystem should handle up to 200 transactions per second, ensuring stable performance during peak loads.

3.2 Reliability

• Uptime: The subsystem must maintain 99.95% uptime annually, allowing for a maximum downtime of 4.4 hours per year.

• Error Rate: The error rate should not exceed 0.005% of transactions, ensuring high accuracy and reliability.

3.3 Security

• Data Protection: Sensitive data must be encrypted using AES-256 both at rest and in transit.

• Access Control: Access must be managed via role-based access control (RBAC), ensuring users have only the permissions necessary for their roles.

3.4 Usability

• Interface Design: The user interface must be intuitive and follow established design guidelines, such as Material Design or Human Interface Guidelines.

• Documentation: Provide a user manual, system architecture guide, and API documentation to support users and developers.

---

4. Interface Requirements

4.1 External Interfaces

Interface 1: User Authentication Service

• Description: Communicates with an external service to validate user credentials.

• Data Formats: JSON

• Communication Protocols: HTTPS

• Authentication: OAuth 2.0 Bearer Token

Interface 2: Payment Gateway API

• Description: Integrates with an external payment gateway for processing transactions.

• Data Formats: JSON

• Communication Protocols: HTTPS

• Authentication: API Key

4.2 Internal Interfaces

Interface A: Data Management Module

• Description: Connects with the Data Management Module for data storage and retrieval.

• Data Formats: JSON

• Communication Protocols: HTTP

• Authentication: Internal API Key

Interface B: Notification Service

• Description: Sends notifications via the internal Notification Service.

• Data Formats: JSON

• Communication Protocols: HTTP

• Authentication: Internal API Key

---

5. Constraints

5.1 Hardware Constraints

• Processor: Minimum 2.5 GHz quad-core.

• RAM: 16 GB.

• Disk Space: 500 GB.

• Network: 1 Gbps interface.

5.2 Software Constraints

• Operating System: Linux Ubuntu 20.04 LTS or later.

• Database: PostgreSQL 13.3 or later.

• Web Server: Apache 2.4 or later.

• Programming Libraries:

  • Python: 3.8 or later.

  • Django: 3.2 or later.

  • Node.js: 14.x or later.

5.3 Environmental Constraints

• Temperature: 10°C to 35°C.

• Humidity: 20% to 80% (non-condensing).

---

6. Glossary

• API (Application Programming Interface): A set of rules and tools for building software applications, allowing different systems to communicate.

• RBAC (Role-Based Access Control): A method of regulating access to computer systems based on the roles of individual users within an organization.

---

7. Appendix

7.1 Additional Information

Supporting Documentation:

• Design Diagrams: Includes component diagrams, sequence diagrams, and deployment diagrams.

• Data Flow Charts: Visuals depicting data movement, such as Data Flow Diagrams (DFD).

• Configuration Files: Examples of required configuration settings.

• API Documentation: Details on API endpoints, request/response formats, and authentication.

7.2 Diagrams

• System Architecture Diagram:

  Shows the overall structure of the subsystem and its interactions.

• Flowchart:

  Depicts key processes or workflows within the subsystem.

Requirements Templates @ Template.net