Design Principles of SUSANOO

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SUSANOO separates a Python DeviceClass, which implements instrument control, from a communication Frame, which exposes that class over a network. A DeviceClass is an ordinary Python class independent of transport. It can be used directly in a local program; a device server and client/DeviceProxy are needed only for network access.

Local:    Application → DeviceClass → Instrument
Network:  Application → Client / DeviceProxy → Communication Frame → DeviceClass → Instrument

Transports and exposed APIs

• ese774 Frame: FastAPI/HTTP transport, supporting dynamic exposure of DeviceClass members, explicit Pydantic/OpenAPI definitions, and dedicated routers. Its BL774-style background does not imply full protocol compatibility.
• gRPC Frame: Method discovery through Describe and invocation through Call / StreamCall. This is not the same API-definition mechanism as HTTP OpenAPI.
• Tango Frame: Another supported transport family. Check each device package for actual Frame support and startup scripts.
• DDS: A transport considered in the original design discussion, not presented here as a verified current distribution or deployment option.

Abstracting transports does not guarantee identical capabilities, data types, or event behavior across Frames. Validate API exposure, type conversion, error propagation, and concurrency against the instrument and transport in use.

Getting started

• Installation
• Device server development
• Dynamic dispatch and explicit APIs
• DeviceProxy and Factory

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Author

• Kengo NAKADA