pubsub.js

// get xml file & publish
km.core = {
	url: 'someDir/someFile',
	fetch: $.get(url, function(xml) {
		$.publish('xmlFetch', [xml]);
	})
};

// subscribe to xml file and do stuff
km.widget.edVolGraph = {
	handle: 'undefined',
	load: function(location) {
		km.widget.edVolGraph.handle = $.subscribe('xmlFetch', function() {
				// do stuff
		});
	}
};

km.core.fetch(); // publish
km.widget.edVolGraph.load('south'); // subscribe
km.widget.edVolGraph.load('north'); // subscribe
$.unsubscribe(km.widget.edVolGraph.handle); // unsubscribes both!

// if a user wants to kill just one of the widgets
// how can you unsubscribe that one widget without
// unsubscribing the other