Callback callback1 = new TestCallback ("Callback 1");
serviceClient.sendReceiveNonBlocking(getEchoOMBlock("echo1",sequenceKey),callback1);
Callback callback2 = new TestCallback ("Callback 2");
serviceClient.sendReceiveNonBlocking(getEchoOMBlock("echo2",sequenceKey),callback2);
Callback callback3 = new TestCallback ("Callback 3");
serviceClient.sendReceiveNonBlocking(getEchoOMBlock("echo3",sequenceKey),callback3);
while (!callback3.isComplete()) {