File snippets from the Horse Race demonstration.

horserace-1.js

// Connect to Diffusion
function connectToDiffusion() {
	console.log("Connecting to Diffusion...");
    diffusion.connect({
        principal : diffusionUser,
        credentials : diffusionPassword,
        host : diffusionHost,
        port : diffusionPort,
        secure : false, 
    }).then(onConnectSuccess, onConnectError);
    

horserace-2.js

		// Create the JSON topic
		session.topics.add(diffusionTopic, diffusion.topics.TopicType.JSON).then(
            function(result) {
                console.log('JSON Topic Added : ' + result.topic);
			  
                // Start the updates to the topic
                updateTopic(session);
            },
            function(error) {
                console.log('JSON Topic Add Failed : ' + error);
            });

horserace-3.js

function updateTopic(session) {
    // Update the topic with the data from the current row
    var json = JSON.parse(horseData[fileRowNum]);
    session.topics.update(diffusionTopic, json).then(onComplete, onError);
    fileRowNum = fileRowNum + 1;
    if (fileRowNum == horseData.length-1) {
        fileRowNum = 0;
    }

    // Delay until the next record is published
    setTimeout(function(){updateTopic(session)}, delay);

    function onComplete(status) {
    }

    function onError(error) {
        console.log("onError!" + error);
    }
}

horseraceclient-1.js

		// Connection established
		var datatype = diffusion.datatypes.json();
		session.subscribe(diffusionTopic).asType(datatype).on({
			subscribe : function(topic) {
				// Subscribed to a particular topic
			},
			unsubscribe : function(topic, reason) {
				// Unsubscribed from a particular topic
			},
			value : function(topic, specification, newValue, oldValue) {
				// Get the JSON object and plot it on the race course
				var jsObj = newValue.get();
				

horseraceclient-2.js

				// Convert the x and y position to absolute longitude and latitude from data origin. The identifier
				// of the horse is the last two digits of the I field.
				var horseId = parseInt(jsObj.I.substr(-2), 10);
				var horseX = jsObj.X * cosmologicalConstant; 
				var horseY = jsObj.Y * cosmologicalConstant;
				var radiusEarth = 6378137; // In meters
				var horseLatitude  = dataOriginLat  + ( horseY / radiusEarth) * (180 / Math.PI);
				var horseLongitude = dataOriginLong + ( horseX / radiusEarth) * (180 / Math.PI) / Math.cos(dataOriginLat * Math.PI/180);
				
				// Place a marker for the horse on the map at the new location, creating a new one on the fly if it does not already exist
				if( horses[horseId - 1] === undefined) {
					// Create the new marker and append it to the array
					var image = "icons/horse" + horseId + ".png";
					var marker = new google.maps.Marker({
						position: new google.maps.LatLng(horseLatitude, horseLongitude),
						map: map,
						icon : image
					});
					horses[horseId - 1] = marker;
					numberOfHorses = numberOfHorses + 1;
				}
				else {
					// We already had a marker for this horse, so move it...
					horses[horseId - 1].setMap(null);
					horses[horseId - 1].setPosition(new google.maps.LatLng(horseLatitude, horseLongitude));
					horses[horseId - 1].setMap(map);
				}