@autocodingsystems/gateway-client/lib/api/signalrconnection.js

Library and commandline utility to control the acs gateway - device drivers for the most common industrial production line devices

var signalR = require('signalr-client');
var http = require('http');

module.exports = function wrap(gateway) { return function makeSignalRConnection(subscriptions, onconnection, onevent, onerror) {
    var active = true;

    var client  = new signalR.client(
        gateway + "/signalR",  //signalR service URL
        ['deviceNotificationHub'],                      // array of hubs to be supported in the connection
        10,                                //optional: retry timeout in seconds (default: 10)
        true                              //optional: doNotStart default false
    );

    client.on(
        'deviceNotificationHub',		// Hub Name (case insensitive)
        'eventOccured',	// Method Name (case insensitive)
        function(deviceId, timestamp, eventClass, event, subKey, message) { // Callback function with parameters matching call from hub
            
            if (!active) {
                client.end();
                return;
            }

            var payloadMsg = message;
            try {
                payloadMsg = JSON.parse(message);
            } catch(e) {
            }

            var tag = subscriptions.filter(s => s.subscription == subKey)[0].tag;

            onevent({
                gateway,
                deviceId,
                timestamp,
                eventClass,
                event,
                subKey,
                tag,
                message: payloadMsg
            })
        }
    );

    client.serviceHandlers = { //Yep, I even added the merge syntax here.
        bound: function() { },
        connectFailed: function(error) { onError('Connect Failed', error); },
        connected: onConnected,
        disconnected: onDisconnected,
        reconnected: onConnected,
        onerror: function (error) { onError('Error', error); },
        messageReceived: function (message) { return false; },
        bindingError: function (error) { onError('Binding Error', error); },
        connectionLost: onDisconnected,
        reconnecting: function (retry /* { inital: true/false, count: 0} */) {
            return !active; 
        },
    };

    client.serviceHandlers.onUnauthorized = function (res) {
        //Do your Login Request
        var location = res.headers.location;
        var result = http.get(location, function (loginResult) {
            //Copy "set-cookie" to "client.header.cookie" for future requests
            client.headers.cookie = loginResult.headers['set-cookie'];
        });
    }

    function onConnected() {
        if (!active) {
            client.end();
        }

        var tags = subscriptions.map(s => s.tag);

        onconnection({
            status: true,
            tags: tags
        });
        
        subscriptions.forEach(subscription => {
            client.invoke(
                'deviceNotificationHub', // Hub Name (case insensitive)
                'Subscribe',	// Method Name (case insensitive)
                subscription.subscription //additional parameters to match called signature
            );
        });
    }

    function onDisconnected() {
        var tags = subscriptions.map(s => s.tag);

        onconnection({
            status: false,
            tags: tags
        });
    }

    function onError(errorType, error) {
        var tags = subscriptions.map(s => s.tag);
        
        onerror({
            type: errorType,
            error: error,
            tags: tags
        });
    }

    client.start();

    function stop() {
        active = false;
        client.end();
    }

    return {
        stop
    };
}}