Question

I have a simple server, you send it a command, it replies back with an \r\n delimited response.

So I tried to get a command( callback ) method on my client. Check out this simplified code snippet:

var net = require('net');

var Client = function() {
   this.data = "";
   this.stream = net.createConnection(port, host);

   this.stream.on('data', function( data ) {
        var self = this;

        this.data += data;
        self.process()            
   };

   this.process = function() {
       var _terminator = /^([^\r\n]*\r\n)/;

       while( results = _terminator.exec(this.data) ) {
            var line = results[1];
            this.data = this.data.slice(line.length);

            this.emit('response', data);
       };
   };

   this.sendCommand = function( command, callback ) {
       var self = this;

       var handler = function( data ) {
            self.removeListener('response', handler);

            callback && callback(data);
       }

       this.addListener('response', handler);

       this.stream.write(command);
   };

   this.command_1 = function( callback ) {
        this.sendCommand( 'test', callback );
   };

   this.command_2 = function( callback ) {
        this.sendCommand( 'test2', callback );
   };
}

So I am doing a client.command_1( function() {} ) and then a client.command_2( function() {}) but in the callback of my command_2 I am getting the response from command_1.

Is this the right way to implement such a thing?

Answer 1

When you execute

client.command_1( function() { 1; } );
client.command_2( function() { 2; } );

you add both callbacks as ‘result’ listeners, and when emit('result') happens for the first time, both callback are called (then first callback removes itself from a list). You need to set callbacks on some kind of request object, not on a client.

simple code on what happens in your client:

var e = new EventEmitter();
e.on('result', function() { console.log(1); });
e.on('result', function() { console.log(2); });
// ...
e.emit('result'); // here we trigger both callbacks which result in printing "1\n2\n"