List<String> devices = Datastore.getDevices();
String status;
if (devices.isEmpty()) {
status = "Message ignored as there is no device registered!";
} else {
Queue queue = QueueFactory.getQueue("gcm");
// NOTE: check below is for demonstration purposes; a real
// application
// could always send a multicast, even for just one recipient
if (devices.size() == 1) {
// send a single message using plain post
String device = devices.get(0);
queue.add(withUrl("/send").param(
SendMessageServlet.PARAMETER_DEVICE, device));
status = "Single message queued for registration id " + device;
} else {
// send a multicast message using JSON
// must split in chunks of 1000 devices (GCM limit)
int total = devices.size();
List<String> partialDevices = new ArrayList<String>(total);
int counter = 0;
int tasks = 0;
for (String device : devices) {
counter++;
partialDevices.add(device);
int partialSize = partialDevices.size();
if (partialSize == Datastore.MULTICAST_SIZE
|| counter == total) {
String multicastKey = Datastore
.createMulticast(partialDevices);
logger.fine("Queuing " + partialSize
+ " devices on multicast " + multicastKey);
TaskOptions taskOptions = TaskOptions.Builder
.withUrl("/send")
.param(SendMessageServlet.PARAMETER_MULTICAST,
multicastKey).method(Method.POST);
queue.add(taskOptions);
partialDevices.clear();
tasks++;
}
}
status = "Queued tasks to send " + tasks