ophyd-websocket

Experimental python based websocket used to live-monitor and set EPICS/ophyd device values through a web browser.

Use Case

If you are building a web browser application and need to:

• Monitor the current value of an EPICS device
• Set the value of an EPICS device
• Know immediately when an EPICS device disconnects/reconnects

then ophyd-websocket can provide these features.

How it works

Clients send a message to ophyd-websocket with the name of a pv. The websocket then calls EpicsSignal(your_pv) to establish a connection and provide functionality including live updates when a value changes, the device connection status changes, or to set the value. The get and set methods are utilized with ophyd.

Ophyd async is not currently supported.

A single websocket instance can hold any number of pv subscriptions.

Demo Video

Future plans

1. Integration with the Queue Server to avoid conflicts when the RE is active
2. Automatically instantiate connections to devices found from the Queue Server allowable devices.
3. Ophyd-async support

Installation

git clone https://github.com/bluesky/ophyd-websocket.git 

Optionally set up a conda environment

conda create -n ophyd_websocket python=3.12
conda activate ophyd_websocket

Install requirements

#/ophyd-websocket
pip install -r requirements.txt

Starting the Websocket

Start the websocket with the default host and port options

#/ophyd-websocket
python server/ophyd_ws_server.py

Start the websocket with host and port set in command line

#/ophyd-websocket
uvicorn server.ophyd_ws_server:app --reload --host 0.0.0.0 --port 8000

Messages and Responses

sequenceDiagram
        Browser<<-->>Ophyd-Websocket: Connect
        Browser->>Ophyd-Websocket: Subscribe DMC01
        activate Ophyd-Websocket
        Ophyd-Websocket->>EPICS: Subscribe DMC01
        EPICS<<-->>Ophyd-Websocket: DMC01 Updates
        Ophyd-Websocket->>Browser: DMC01 metadata
        Ophyd-Websocket->>Browser: DMC01 current value
        deactivate Ophyd-Websocket
        External->>EPICS: caput DMC01 newValue
        EPICS->>Ophyd-Websocket: DMC01 update
        activate Ophyd-Websocket
        Ophyd-Websocket->>Browser: DMC01 current value
        deactivate Ophyd-Websocket

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