MDM Client: Subscribing to Event Notifications

This document provides client application developers the background needed to subscribe to YOUnite MDM notification topics and event types so they can receive real-time updates to MDM events.  A topic is created for each MDM zone and for each MDM zone there are various notification types.

Note: Currently we are using simple username/password authentication between the YOUnite UI and AMQ. All interaction between zones and clients that are tied to zones (e.g. YOUnite UI) should interact with AMQ with OAuth tokens or even better SSO→OAuth.  See YOUMDM-103.

Subscribing to Topics

MDM uses the Apache ActiveMQ messaging system which leverages the STOMP text-based messaging protocol.  STOMP allows clients to be written easily.  A STOMP protocol implementation in node.js can be found here.

Adding STOMP

Add the following libraries in your local workspace:

• amq_jquery_adapter.js
• amq.js
• stomp.js
  
  

Note: Hari is working on inserted the STOMP libraries into the project . There may be some changes to the following using npm to install the libraries.

Injecting STOMP Libraries

Directly add to the library section of your source code e.g. (use the appropriate path to your libraries):

{src: `${this.ASSETS_SRC}/vendor-libs/js/amq_jquery_adapter.js`, inject: true, vendor: true},
{src: `${this.ASSETS_SRC}/vendor-libs/js/amq.js`, inject: true, vendor: true},
{src: `${this.ASSETS_SRC}/vendor-libs/js/stomp.js`, inject: true, vendor: true},

Subscribing to a Topic

Setup your credentials in your configuration (e.g. config.ts)

//
// Define these in a config file e.g. config.ts
//
ACTIVEMQ_CLIENT: process.env.ACTIVEMQ_CLIENT ? process.env.ACTIVEMQ_CLIENT : 'ws://docker.local:61614',
ACTIVEMQ_USER_NAME: process.env.ACTIVEMQ_USER_NAME ? process.env.ACTIVEMQ_USER_NAME : 'admin',
ACTIVEMQ_PASSWORD: process.env.ACTIVEMQ_PASSWORD ? process.env.ACTIVEMQ_PASSWORD : 'admin',

Setup your handler:

subscribeNotification() {
	this.loggedInZoneUuid = localStorage.getItem('zoneUuid');
	this.client = Stomp.client(Config.ACTIVEMQ_CLIENT);
	let topicUrl = '/topic/' + this.loggedInZoneUuid;
	let connectHeaders = {
		login: Config.ACTIVEMQ_USER_NAME,
		passcode: Config.ACTIVEMQ_PASSWORD,
		'client-id': this.loggedInZoneUuid
	};
	let componentRef = this;
	
	let callback = function (message) {
		// called when the client receives a STOMP message from the server
		componentRef.toastr.info(message.body);
		componentRef.incrementUnreadNotificationCount();
	};
	let subscribeHeaders = {'activemq.subscriptionName': this.loggedInZoneUuid};
	this.client.connect(connectHeaders, function () {
		componentRef.client.subscribe(topicUrl, callback, subscribeHeaders);
	}
);

Disconnect from the handler on logout, this should be in the same file as the above handler:

this.client.disconnect();

Notification Event Types

The following is list of event types that a subscriber can be notified of on a per zone (topic) basis.  Each time an event is triggered it publishes a new notification of a given event type  .  

Notification Event Response Body

The notification's JMS header includes the following:

Requesting Notification Log

A client can make a request to get the log history for all notifications sent to their zone.  The user provides their zone and a from and to date.