private Object executeOperation(HazelcastInstance node, Operation op)
     throws InterruptedException, ExecutionException {
   InternalOperationService operationService = getOperationService(node);
   Address address = getAddress(node);
   InternalCompletableFuture future =
       operationService.invokeOnTarget(MapService.SERVICE_NAME, op, address);
   return future.get();
 }
 public void handleClientMessage(ClientMessage clientMessage, Connection connection) {
   int partitionId = clientMessage.getPartitionId();
   final MessageTask messageTask = messageTaskFactory.create(clientMessage, connection);
   if (partitionId < 0) {
     executor.execute(messageTask);
   } else {
     InternalOperationService operationService = nodeEngine.getOperationService();
     operationService.execute(messageTask);
   }
 }
  private InternalCompletableFuture invoke() {
    Operation op =
        new Operation() {
          @Override
          public void run() throws Exception {
            sleepMillis(1000);
          }

          @Override
          public Object getResponse() {
            return RESULT;
          }
        };
    return opService.invokeOnPartition(null, op, 0);
  }
 @Override
 protected InvocationBuilder getInvocationBuilder(Operation op) {
   final InternalOperationService operationService = nodeEngine.getOperationService();
   return operationService.createInvocationBuilder(getServiceName(), op, parameters.target);
 }