node-amqp exchange.publish callb

I met a problem when using exchange.publish to push message.
my code fragment as follow

exc.pushblish('', JSON.stringify(message), {}, function(){
  console.log("message published");
});

Every time push the message, would output the log, sadly it can't work as my expect.
After read the doc exchange.publish(routingKey, message, options, callback), I found some description:

callback
is a function that will get called if the exchange is in confirm mode, the value sent will be true or false, this is the presense of a error so true, means an error occured and false, means the publish was successfull

my exchange object new as:

var exc = connection.exchange("ethereum.exchange", options = { type: 'fanout', durable: true, autoDelete: false  }, function(exchange){
  console.log("exchange" + exchange.name + "is opened");
});

horriblely! without confirm mode when create exchange, when publish message, it would the callback function would not be called.
So, to solve the problem, we should add confirm: true for connection.exchange function second args options.