mashup-opcua-counter-v1

README.txt

npm install @node-wot/core
npm install @node-wot/binding-opcua
npm install @node-wot/binding-http

# Demo

## 1. Open counter website 

Open http://plugfest.thingweb.io/examples/counter.html and listen on change events.
Note: Doing so the counter value will be updated in the UI once "someone" changes the value

## 2. Start OPCUA demo

node opcua-mashup-counter.js

Note: it reads the pumpvalue every X seconds and
* increments the counter IF the pumpspeed is greater than 200
* decrements the counter IF the pumpspeed is equal/lower than 200

opcua-mashup-counter.js

// OPCUA Mashup
Servient = require("@node-wot/core").Servient;
OPCUAClientFactory = require("@node-wot/binding-opcua").OPCUAClientFactory;
HttpClientFactory = require("@node-wot/binding-http").HttpClientFactory;

Helpers = require("@node-wot/core").Helpers;

const thingDescriptionOPCUA = {
    "@context": "https://www.w3.org/2019/wot/td/v1",
    "@type": ["Thing"],
    securityDefinitions: { nosec_sc: { scheme: "nosec" } },
    security: "nosec_sc",
    title: "servient",
    description: "Demo OPCUA Server",
    properties: {
        pumpSpeed: {
            description: "the pump speed",
            type: "number",
            forms: [
                {
                    href: "opc.tcp://opcuademo.sterfive.com:26543", // endpoint
                    op: ["readproperty", "observeproperty"],
                    "opcua:nodeId": "ns=1;s=PumpSpeed",
                },
            ],
        },
    },
};

// >  200 increment
// <= 200 decrement
async function updateCounter(thingOPCUA, thingHttpCounter) {
	const content = await thingOPCUA.readProperty("pumpSpeed");
	const value = await content.value();
	if (value != null) {
		const json = (value).valueOf();
		console.log("OPCUA Pump Speed is", json);
		if (json > 200) {
			console.log("\t increment HTTP counter");
            await thingHttpCounter.invokeAction("increment");
		} else {
			console.log("\t decrement HTTP counter");
            await thingHttpCounter.invokeAction("decrement");
		}
	}
}

const servient = new Servient();
servient.addClientFactory(new OPCUAClientFactory());
servient.addClientFactory(new HttpClientFactory(null));

let wotHelper = new Helpers(servient);
wotHelper
    .fetch("http://plugfest.thingweb.io:8083/counter")
    .then(async (thingDescriptionCounter) => {
        try {
            const wot = await servient.start();
			
			// OPCUA
			const thingOPCUA = await wot.consume(thingDescriptionOPCUA);
			
			// HTTP counter
            const thingHttpCounter = await wot.consume(thingDescriptionCounter);
	
			// read pumpSpeed every 5 secs and update counter accordingly
			setInterval(() => {
				updateCounter(thingOPCUA, thingHttpCounter);
			}, 5000);

        } catch (err) {
            console.error("Script error:", err);
        }
    })
    .catch((err) => {
        console.error("Fetch error:", err);
    });