@isaac-platform/isaac-integration-sdk/heartbeat.js

A Typescript SDK for integrating with ISAAC

import { EventEmitter } from "events";
import isaacConnection from "./controller/isaac";
export class Heartbeat extends EventEmitter {
    /**
     * Creates ISAAC heartbeat handler.
     */
    constructor() {
        super();
        /**
         * var status represents the connection to ISAAC
         * can be one of:
         * - uninitialized
         * - starting
         * - connected
         * - disconnected
         * - error
         */
        this.status = "uninitialized";
        /**
         * Starts heartbeat process and updates status.
         * @param interval {number} - (optional) override default 5000 ms interval
         */
        this.start = (interval) => {
            if (this.beating)
                return; // Only one heartbeat running at a time.
            this.intervalID = setInterval(this.beat, interval || this.interval);
            this.beating = true;
            this.updateStatus("starting");
        };
        /**
         * Stops heartbeat process and updates status.
         */
        this.stop = () => {
            if (!this.beating)
                return; // Can't stop if not running.
            clearInterval(this.intervalID);
            this.beating = false;
            this.updateStatus("disconnected");
        };
        /**
         * Updates the connection status and emits on a change.
         * @param state {string} - New state to define and announce
         */
        this.updateStatus = (state) => {
            if (this.status === state)
                return;
            this.status = state;
            this.emit('statusChange', state);
        };
        /**
         * Emits heartbeat messages.
         * @param messages
         */
        this.emitHeartbeatMessages = (messages) => {
            for (let message of messages) {
                this.emit(message.type, message);
            }
        };
        /**
         * Makes async heartbeat PUT to ISAAC. Updates status to "connected" or "error" depending on acknowledgement from ISAAC.
         * TODO: Implement ISAAC message bus.
         */
        this.beat = () => {
            isaacConnection.putRequest(`subsystems/${isaacConnection.subsystemID}/heartbeat`, {}).then((response) => {
                this.updateStatus("connected");
                if (response.message && response.message.length > 0)
                    this.emitHeartbeatMessages(response.message);
            }).catch((error) => {
                this.updateStatus("error");
            });
        };
        this.beating = false;
        this.status = "uninitialized";
        this.interval = 5000; //Default interval is 5 seconds.
    }
    emit(event, ...args) {
        return super.emit(event, ...args);
    }
    on(event, listener) {
        return super.on(event, listener);
    }
    off(event, listener) {
        return super.off(event, listener);
    }
}