Should I use PI Web API or AF SDK for my application?
Should I use PI Web API or AF SDK for my application?
Both PI Web API and AF SDK provide programmatic access to PI System data. The right choice depends on your platform, deployment, and use case.
PI Web API
RESTful HTTP API — works from any language or platform.
Best for:
- Web applications (JavaScript, React, Angular)
- Cross-platform clients (Python, Java, Go, mobile)
- Cloud-hosted applications
- Microservices and containerized architectures
- Integration with non-Windows systems
Pros:
- Language-agnostic — anything that can make HTTP requests
- No client-side installation required
- Works through firewalls (HTTPS)
- Built-in Swagger documentation
Cons:
- HTTP overhead for high-frequency reads
- No real-time push (must poll or use SignalR channels)
- Bulk operations are slower than native SDK
AF SDK
.NET library — native, high-performance access.
Best for:
- Windows desktop applications (.NET)
- High-throughput data writes
- Complex AF operations (bulk element creation, template management)
- Real-time data subscriptions (AFDataPipe)
- PI System administration tools
Pros:
- Highest performance — native protocol
- Real-time subscriptions via data pipes
- Full PI System functionality
- Strong typing and IntelliSense
Cons:
- Windows and .NET only
- Requires PI AF Client installation
- Tighter coupling to PI infrastructure
Decision Matrix
| Criteria | PI Web API | AF SDK |
|---|---|---|
| Language | Any | .NET only |
| Platform | Any OS | Windows |
| Performance | Good | Best |
| Real-time | Polling | Native data pipes |
| Cloud-ready | Yes | Limited |
| Install required | No | Yes |
Hybrid Approach
Many organizations use both: AF SDK for backend services running on-premises, and PI Web API for web frontends and cloud integrations.
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