Design an Online Collaborative Spreadsheet

Functional Requirements

1. Real-Time Collaboration

   • Multiple users should be able to edit the same spreadsheet simultaneously.
   • Changes made by one user should be reflected in real-time for all other users.

2. User Authentication and Authorization

   • Users must be able to securely log in to the system.
   • Access control to ensure only authorized users can view or edit specific spreadsheets.

3. Spreadsheet Features

   • Basic spreadsheet functionalities such as cell editing, formatting, and formula calculations.
   • Support for multiple sheets within a single document.
   • Ability to insert, delete, and move rows and columns.

4. Version Control

   • Track changes and maintain a history of edits.
   • Allow users to revert to previous versions of the spreadsheet.

5. File Management

   • Create, save, and delete spreadsheets.
   • Organize spreadsheets into folders or categories.

6. Import/Export

   • Support for importing and exporting spreadsheets in common formats like CSV, XLSX, etc.

7. Commenting and Annotation

   • Users should be able to add comments to specific cells or ranges.

8. Search and Filter

   • Ability to search for specific data within the spreadsheet.
   • Filter data based on specific criteria.

9. Notifications

   • Notify users of changes made to shared spreadsheets.

10. Offline Editing

    • Allow users to edit spreadsheets offline and sync changes once back online.

Non-Functional Requirements

1. Scalability

   • The system should handle a large number of concurrent users and spreadsheets.
   • Efficiently manage large datasets within spreadsheets.

2. Performance

   • Real-time updates should be quick and seamless.
   • Low latency for user interactions and data retrieval.

3. Reliability and Availability

   • Ensure high availability of the service with minimal downtime.
   • Implement data redundancy and backup strategies.

4. Security

   • Protect user data through encryption and secure data transmission.
   • Implement robust authentication mechanisms.

5. Data Consistency

   • Ensure data consistency across all users and devices.

6. Interoperability

   • The system should be accessible via different platforms (web, mobile, etc.).

7. Extensibility

   • Design the system to accommodate future feature additions and integrations.

8. Localization and Internationalization

   • Support multiple languages and regional settings for global users.

9. Resource Efficiency

   • Optimize for minimal resource usage on both client and server sides.