Quick Node.js script to look at the XML feed on ActiveMQ to demonstrate a way of doing this if not hooked into something like Nagios or antoehr monitoring service

monitor.js

var http = require('http'),
    util = require('util'),
    url = require('url'), 
    fs = require('fs'),
    xml2js = require('xml2js');

try {
	var amq_client = http.request(8161, 'localhost');
	var parser = new xml2js.Parser();
	var MAX_PENDING = 5; //high water mark set for pending messages
	var MAX_DIFF = 5; //high water mark variable set
	var LOG_HOME = '/path/to/amq.log';
} catch (err) {
	console.log('set up error: '+err);
}


function get_queue() {

	var request = amq_client.request("GET", "/admin/xml/queues.jsp", {"host": "localhost"}); //must be changed to read the timelines
	request.addListener("response", function (response) {
		var body = "";
		
		response.addListener("data", function(data) {
			body += data;
		});
		
		response.addListener("end", function() {
			parser.on('end', function(result) {
				var queues = JSON.parse(JSON.stringify(result));
			    for(var i in queues.queues.queue) {
			    	var name = queues.queues.queue[i].$.name;;
			    	var q = queues.queues.queue[i];
			    	for (var k in q.stats) {
			    		var size = q.stats[k].$.size;
			    		var enq = q.stats[k].$.enqueueCount;
			    		var deq = q.stats[k].$.dequeueCount;
			    		
			    		if (size > MAX_PENDING) {
			    			var writeStream = fs.createWriteStream(LOG_HOME, {'flags':'a'});
			    			writeStream.write('ERROR: Queue: '+name+'. Pending queue size is too large. Pending size is '+ size + "\n");
			    		}
			    		
			    		if (enq + MAX_DIFF > deq) {
			    			var writeStream = fs.createWriteStream(LOG_HOME, {'flags':'a'});
			    			writeStream.write('ERROR: Queue: '+name+'. Messages are building up. Enqueue size: '+ enq +' dequeue is '+deq + "\n");
			    		}
			    	}
			    }
			});
			parser.parseString(body);
	    });
	});
	
	request.end();

} //end get_queue

setInterval(get_queue, 5000);

http.createServer(function(req, resp){}).listen(8002);