Nodejs socket client - callback for each request

Question

I have the following code

var net = require('net');

var client = new net.Socket();
client.connect(1337, '127.0.0.1', function() {
    console.log('Connected');
    client.write('Hello, server! Love, Client.');
});

client.on('data', function(data) {
    console.log('Received: ' + data);
    client.destroy(); // kill client after server's response
});

I need to send several messages at once to the server and I need to process each of the answers, it turns out that Node is asynchronous, I mean, I don’t have a response order. the commands below trigger the event client.on('data'function(data) {... however I can not know exactly the response of each request, the ideal would be to execute synchronously but not to be able.

   client.write('Algumacoisa1');
   client.write('Algumacoisa2');
   client.write('Algumacoisa3');

By the manual net socket socket.write(data[, encoding][, callback]) I saw that I can use it like this :

  client.write('algumacoisa', 'utf8', function(data){
     console.log(data); //data sempre é undefined

   })

summing up, I want for each client.write I get your reply and only then I send more client.writeto the server.

I know this whole problem is because Node is asynchronous, how to solve?

Answer 1

You can use the async.series for that reason:

async.series([function(done){
    client.write('uma mensagem', 'utf8', function(data){
      console.log('primeira mensagem enviada');;
      done();
    });
  },function(done){
    client.write('outra mensagem', 'utf8', function(data){
      console.log('segunda mensagem enviada');
      done();
    });
  },function(done){
    client.write('terceira mensagem', 'utf8', function(data){
      console.log('terceira mensagem enviada');
      done();
    });
  },function(done){
    console.log('todas mensagens enviadas');
    done();
}]);

This code will only send the next message when the previous one receives a reply.