uopi

A web-based HMI (Human-Machine Interface) for monitoring and controlling EPICS-based scientific and industrial control systems.

uopi runs as a single portable binary. Access it from any browser — including over an SSH tunnel — with no client-side installation required.

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Features

• Live data from EPICS (Channel Access / PVAccess) and user-defined synthetic signals
• Web-based HMI editor — drag-and-drop widgets, resize, align, undo/redo — saved as XML
• Rich widget library — gauges, LEDs, bars, plots (time series, FFT, waterfall, histogram), controls
• Multiple concurrent clients sharing the same data subscriptions
• Historical data navigation via EPICS Archive Appliance integration
• Synthetic signals — compose, filter, and transform existing signals with a DSP pipeline or Lua scripts
• Single binary with embedded frontend; no runtime dependencies

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Quick Start

Prerequisites

• EPICS Base installed (for the EPICS data source; libca must be linkable)
• Go 1.22+
• Node.js 20+ and npm

Build

make all

The binary is written to dist/uopi.

Run

./dist/uopi --config uopi.toml

Then open http://localhost:8080 in your browser.

SSH tunnel example:

ssh -L 8080:localhost:8080 user@controlhost
# then open http://localhost:8080 locally

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Configuration

Create uopi.toml (or copy and edit the example):

[server]
listen    = ":8080"
storage_dir = "./interfaces"   # where interface XML files are stored

[datasource.epics]
enabled      = true
ca_addr_list = ""              # overrides EPICS_CA_ADDR_LIST if non-empty
archive_url  = ""              # EPICS Archive Appliance base URL

[datasource.synthetic]
enabled          = true
definitions_file = "./synthetic.json"

All settings can be overridden with environment variables using the prefix UOPI_ and double underscores for nesting, e.g. UOPI_SERVER_LISTEN=":9090".

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Development

See docs/TECHNICAL_SPEC.md for full architecture details.

# Backend only (with stub data source)
go run ./cmd/uopi

# Frontend dev server (proxies /api to backend at :8080)
cd web && npm install && npm run dev

# Run backend tests
go test ./...

# Run a single backend test
go test ./internal/broker/... -run TestFanOut

# Frontend type-check
cd web && npm run check

# Frontend lint
cd web && npm run lint

# Full build (frontend + backend)
make all

# Run all tests
make test

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Docs

Document	Description
docs/FUNCTIONAL_SPEC.md	User-facing feature specification
docs/TECHNICAL_SPEC.md	Technology choices, architecture, API design
docs/WORK_PLAN.md	Phased development plan with milestones

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License

TBD