Design
Software Architecture
Define software structure, organization and components following safety classification and development standards.
Summary
The Software Architecture document defines the structure and organization of your medical device software according to IEC 62304 standards. It identifies software items, their interconnections, security measures, and deployment requirements, providing the foundation for software development and verification activities.Why is Software Architecture important?
Software architecture documentation is mandatory under IEC 62304 for medical device software development. It provides the blueprint that guides your development team and demonstrates to regulators that your software is systematically designed and properly structured. The architecture ensures that all software components work together safely and effectively to deliver the intended medical functionality. Without proper architecture documentation, you cannot demonstrate that your software design is appropriate for its intended use, that risks have been properly considered, or that verification activities will be comprehensive. The architecture also serves as the foundation for change control and maintenance throughout the product lifecycle.Regulatory Context
Under 21 CFR Part 820.30 (Design Controls) and FDA Software as Medical Device Guidance:
- Software architecture must be documented as part of design inputs
- Must demonstrate systematic software development approach
- Architecture must support verification and validation activities
- Cybersecurity considerations must be integrated into architecture design
Special attention required for:
- Software as Medical Device (SaMD) classification and risk categorization
- Cybersecurity framework implementation per FDA guidance
- Software lifecycle processes documentation
- Third-party software (SOUP) integration and risk assessment
Guide
Understanding Software Architecture
Software architecture defines the high-level structure of your medical device software. It identifies software items (components), their relationships, and how they work together to deliver medical functionality. The architecture should be detailed enough for auditors to understand your software organization but high-level enough to remain stable throughout development.Software Items and Decomposition
According to IEC 62304, your software system consists of:- Software System: The complete integrated collection of software items
- Software Items: Identifiable parts of the software that can be separately developed and tested
- Software Units: The lowest level components that are not further decomposed
- Frontend/User Interface: Components that users interact with directly
- Backend/Processing Engine: Core logic and data processing components
- Database/Storage: Data persistence and retrieval components
- Communication/Interface: Components that handle external communications
- Medical Algorithm: Core medical functionality and calculations
Software Connections and Deployment
Document how your software items connect and communicate:- Infrastructure: Where each software item is deployed (cloud services, local hardware, mobile devices)
- Hardware Requirements: Minimum specifications needed for each component
- Operating Systems: Supported platforms and versions
- Connections: Data flow and communication between software items
Security and Data Protection
Your architecture must address:- Encryption: How sensitive data is protected in transit and at rest
- Authentication: User verification and access control mechanisms
- Data Security: Protection of patient health information
- Network Security: Secure communication protocols and network protection
Backup and Data Integrity
Document your approach to:- Data Backup: Frequency, location, and methods for data backup
- Recovery Procedures: How data can be restored in case of failure
- Data Integrity: Measures to ensure data accuracy and completeness
- Business Continuity: How the system maintains availability
Minimum System Requirements
Specify the minimum requirements for end-user systems:- Hardware: CPU, memory, storage, and connectivity requirements
- Software: Operating system versions, browser requirements, runtime environments
- Network: Bandwidth, connectivity, and protocol requirements
- Peripherals: Any required external devices or accessories
Example
Scenario: You’re developing a remote patient monitoring system that collects vital signs data from wearable devices and provides analysis to healthcare providers. Your system needs to handle real-time data processing, secure storage, and clinical decision support.Software Items Table
| Software Item | Description | Programming Language (Version) | Framework (Version) |
|---|---|---|---|
| Mobile App | Patient interface for data viewing and device pairing | Swift (5.8), Kotlin (1.8) | iOS SDK (16.0), Android SDK (33) |
| Web Dashboard | Clinician interface for patient monitoring and alerts | TypeScript (5.0) | React (18.2), Node.js (18.16) |
| Data Processing Engine | Real-time vital signs analysis and alert generation | Python (3.11) | FastAPI (0.100), NumPy (1.24) |
| Database System | Secure storage of patient data and clinical records | SQL | PostgreSQL (15.3) |
| Device Gateway | Communication interface with wearable monitoring devices | C++ (17) | Embedded Linux, Bluetooth LE |
Software Connections Table
| Software Item | Infrastructure | Hardware Requirements | Operating System | Connections |
|---|---|---|---|---|
| Mobile App | User devices | 2GB RAM, 1GB storage | iOS 14+, Android 10+ | Data Processing Engine, Device Gateway |
| Web Dashboard | AWS Cloud | 4GB RAM, 2 vCPU | Ubuntu 22.04 LTS | Data Processing Engine, Database System |
| Data Processing Engine | AWS Cloud | 8GB RAM, 4 vCPU | Ubuntu 22.04 LTS | Mobile App, Web Dashboard, Database System |
| Database System | AWS RDS | 16GB RAM, 4 vCPU | PostgreSQL on Linux | Data Processing Engine |
| Device Gateway | Edge device | 1GB RAM, ARM processor | Embedded Linux | Mobile App, wearable devices |
Security Implementation
The system implements end-to-end encryption using AES-256 for data at rest and TLS 1.3 for data in transit. Patient authentication uses OAuth 2.0 with multi-factor authentication. All API communications are secured with JWT tokens and rate limiting. Healthcare provider access is controlled through role-based permissions with audit logging of all data access.Backup Procedures
Patient data is automatically backed up to encrypted AWS S3 storage every 4 hours. Database snapshots are created daily and retained for 30 days. Critical system configurations are version-controlled and backed up to separate geographic regions. Recovery procedures can restore full system functionality within 2 hours of any component failure.Minimum User System Requirements
- For Mobile App: iOS 14.0+ or Android 10+, 2GB RAM, 1GB available storage, Bluetooth 5.0+, internet connectivity
- For Web Dashboard: Modern web browser (Chrome 100+, Firefox 100+, Safari 15+), 4GB RAM, broadband internet connection (5 Mbps minimum)
- For Wearable Devices: Bluetooth Low Energy 5.0+, compatible with iOS/Android pairing protocols
Q&A
How detailed should the software architecture be?
How detailed should the software architecture be?
The architecture should be detailed enough for auditors to understand your software organization and for developers to implement the design, but high-level enough to remain stable throughout development. Focus on software items, their responsibilities, and key interfaces rather than implementation details. Include technology versions and frameworks to demonstrate systematic approach.
How do I handle third-party software in my architecture?
How do I handle third-party software in my architecture?
Third-party software can be integrated as a medical device system module, listed as a supplier, and added to architecture documentation. Create specific subsystem requirements for third-party components and maintain your current device classification. Document all third-party software in your SOUP (Software of Unknown Provenance) list with risk assessments.
What security considerations must be included in the architecture?
What security considerations must be included in the architecture?
Include encryption methods for data protection during transfer and storage, authentication mechanisms, access controls, and network security measures. Document how patient data is protected, how system integrity is maintained, and how cybersecurity risks are mitigated. Consider FDA cybersecurity guidance and MDR requirements for data protection.
How do I document software connections and interfaces?
How do I document software connections and interfaces?
Clearly specify how each software item communicates with others, including data formats, communication protocols, timing requirements, and error handling. Document both internal interfaces between your software items and external interfaces with third-party systems, medical devices, or user systems.
What should be included in minimum system requirements?
What should be included in minimum system requirements?
Specify hardware requirements (CPU, memory, storage), software requirements (operating systems, browsers, runtime environments), network requirements (bandwidth, protocols), and any special peripherals or accessories. These requirements should support your intended use and user environment while ensuring reliable operation.
How does software architecture relate to IEC 62304 classification?
How does software architecture relate to IEC 62304 classification?
Your software safety classification (Class A, B, or C) determines the level of detail required in your architecture documentation. Higher classification levels require more detailed documentation of software items, interfaces, and verification approaches. The architecture must support your chosen development lifecycle and verification strategy.