Subscribe to Kepware with node-opcua

subscribe.js

//Source: https://github.com/node-opcua/node-opcua/wiki/2.0.0-breaking-changes
const {
  OPCUAClient,
  resolveNodeId,
  AttributeIds,
  ClientSubscription,
  ClientMonitoredItem,
  TimestampsToReturn
} = require("node-opcua");

const async = require("async");

const opcua_username = "user";
const opcua_password = "password";
const endpointUrl = "opc.tcp://:49320";
const nodeId = "ns=2;s=Simulation Examples.Functions.Ramp8"

let theSession = null;
let theSubscription = null;

const client = OPCUAClient.create({
  endpoint_must_exist: false
});
async.series([

    // step 1 : connect to
    function(callback) {

      client.connect(endpointUrl, function(err) {
        if (err) {
          console.log(" cannot connect to endpoint :", endpointUrl);
        } else {
          console.log("connected !");
        }
        callback(err);
      });
    },
    
    // step 2 : createSession
    function(callback) {
      client.createSession({
        userName: opcua_username,
        password: opcua_password
      }, function(err, session) {
        if (!err) {
          theSession = session;
        }
        callback(err);
      });

    },
    
    // step 4 : read a variable
    /*
    function(callback) {
        theSession.readVariableValue(nodeId, function(err, dataValue) {
            if (!err) {
                console.log(" temperature = ", dataValue.toString());
            }
            callback(err);
        })
    },
    */
    
    // step 5: install a subscription and monitored item
    function(callback) {
      // create subscription
      theSubscription = ClientSubscription.create(theSession, {
        requestedPublishingInterval: 500,
        requestedLifetimeCount: 1000,
        requestedMaxKeepAliveCount: 20,
        maxNotificationsPerPublish: 10,
        publishingEnabled: true,
        priority: 10
      });
      theSubscription.on("started", function() {
        console.log("subscription started - subscriptionId=", theSubscription.subscriptionId);
      }).on("keepalive", function() {
        console.log("keepalive");
      }).on("terminated", function() {
        callback();
      });

      // install monitored item
      //
      const monitoredItem = ClientMonitoredItem.create(theSubscription, {
          nodeId: nodeId,
          attributeId: AttributeIds.Value
        }, {
          samplingInterval: 500,
          discardOldest: false,
          queueSize: 10
        },
        TimestampsToReturn.Source
      );
      monitoredItem.on("initialized", () => {
        console.log("initialized");
      });

      monitoredItem.on("changed", function(dataValue) {
        //console.log("New Value = ", dataValue.value.value.toString());
        console.log(dataValue);
      });

      setTimeout(function() {
        theSubscription.terminate();
      }, 10000);

    },

    // closing session
    //
    function(callback) {
      console.log(" closing session");
      theSession.close(function(err) {
        console.log(" session closed");
        callback();
      });
    },


  ],
  function(err) {
    if (err) {
      console.log(" failure ", err);
    } else {
      console.log("done!")
    }
    client.disconnect(function() {});
  });