What are some examples of non-functional requirements?

Non-functional requirements (NFRs) are crucial specifications that define how a system operates, rather than what it does. They are essential for ensuring that the software system meets certain qualities or attributes that affect user satisfaction and system performance. Here are some detailed examples of common non-functional requirements across various categories:

1. Performance

• Response Time: The system should respond to user input within 2 seconds under normal load conditions.
• Throughput: The application must support at least 100 transactions per second during peak usage.
• Capacity: The system must be able to handle at least 10,000 simultaneous users without performance degradation.

2. Scalability

• Scalability Requirement: The system should be capable of scaling from 1,000 to 10,000 users with minimal impact on performance by adding additional resources without significant changes to the system architecture.

3. Reliability

• Availability: The system must be operational and available for users 99.9% of the time, excluding scheduled maintenance windows.
• Recovery: In case of a system failure, recovery of operations should not take more than 5 minutes.

4. Usability

• Accessibility: The application must comply with the Web Content Accessibility Guidelines (WCAG) 2.1 at the AA level to ensure accessibility for users with disabilities.
• User Satisfaction: Achieve a user satisfaction rating of at least 80% on usability post-deployment surveys.

5. Maintainability

• Modifiability: Any changes or updates to the system modules should not affect more than 5% of the existing codebase.
• Documentation: All code should be documented to at least 90% completeness to ensure that new developers can understand and maintain the system effectively.

6. Security

• Data Encryption: All user data transmitted over the network must be encrypted using TLS 1.2 or higher.
• Authentication: The system must support two-factor authentication for accessing sensitive data areas.
• Compliance: The system must meet all GDPR requirements for data privacy and user consent.

7. Compliance

• Regulatory Compliance: The software must comply with the Payment Card Industry Data Security Standard (PCI DSS) for handling credit card transactions.
• Legal Compliance: The software must log all data access and changes to comply with the Sarbanes-Oxley Act regulations.

8. Portability

• Cross-Platform Support: The application must be operable on both Windows and macOS without requiring any modifications.
• Browser Compatibility: The web application should be compatible with the latest versions of Chrome, Firefox, Safari, and Edge.

9. Disaster Recovery

• Backup: The system must perform daily backups of all data, which must be stored in at least two geographically separate locations.
• Failover: Implement automatic failover to a secondary data center in case the primary data center goes down.

Conclusion

These examples of non-functional requirements illustrate the importance of defining how a system should behave in terms of performance, reliability, usability, and other operational criteria. By clearly specifying NFRs, you ensure that the system not only functions correctly but also meets the quality standards and operational expectations necessary for a successful deployment and user satisfaction.