opcua-sub-to-websocket

OPC UA Server -> OPC UA Client / WebSocket Server -> WebSocket Client

You can use this to push data from a "OPC UA Subscription" over a WebSocket to the Browser/WebSocket-Client

"opcua-sub-to-websocket" can support multiple WebSocket-Clients and pushes all received subscription-notifications to all WebSocket-Clients.

Startup on Localhost:

Console1: python server.py  
Console2: python client.py  
Console3: python ws_client.py  
And as many Browser instances of test.html as you want!

Provided is a sample "OPC UA Server" which generates random events and datachanges!
The timing can be adjusted in server.py:

async def random_updater(random_node):
    while True:
        await asyncio.sleep(random.randint(1,10)/10) #<-------------
        random_node.set_value(ua.DataValue(ua.Variant(random.randint(70,90), ua.VariantType.UInt64)))
        print(datetime.now(), "datachange")

async def event_gen(myevgen):
        count = 0
        while 1:
            await asyncio.sleep(random.randint(1,10)/10) #<-------------
            myevgen.event.Message = ua.LocalizedText("MyFirstEvent %d" % count)
            myevgen.event.Severity = count
            myevgen.event.MyNumericProperty = count
            myevgen.event.MyStringProperty = "Property " + str(count)
            myevgen.trigger()
            count += 1
            print(datetime.now(), "event")

also provided is a test HTML-Page with some basic JavaScript to connect/reconnect to WebSockets:

<!DOCTYPE html>
<html lang="de">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Andreas Heine</title>
</head>
<body>
<div id="content"> </div>
<script>
    var content = {}
    let data
    function connect() {
      let url = "ws://127.0.0.1:8000";
      let s = new WebSocket(url);
      s.onopen = function(event) {
        console.log(event);
      }
      s.onclose = function(event) {
        console.log(event);
        setTimeout(function() {
          connect();
        }, 2000);
      }
      s.onerror = function(event) {
        console.log(event);
      }
      s.onmessage = function(event){
        data = JSON.parse(event.data);
        //console.log(data);
        if (data.topic == "datachange notification"){
          content[data.payload.node] = {
            value: data.payload.value,
            data: data.payload.data,
          };
        }
        if (data.topic == "event notification"){
          content["Event"] = data;
        }
        if (data.topic == "status change notification"){
          content["Status"] = data;
        }
        document.getElementById("content").innerHTML = JSON.stringify(content);
      }
    }
    connect();
</script>
</body>
</html>

aswell as an python based WebSocket Client :

import asyncio, websockets

async def request():
    uri = "ws://127.0.0.1:8000"
    async with websockets.connect(uri) as websocket:
        while 1:
            msg = await websocket.recv()
            print(msg)

asyncio.get_event_loop().run_until_complete(request())

Interested? Contact me: info@andreas-heine.net

AndreasHeine / opcua-sub-to-websocket

readme

opcua-sub-to-websocket

OPC UA Server -> OPC UA Client / WebSocket Server -> WebSocket Client