var ConversationV1 = require('watson-developer-cloud/conversation/v1');

var conversation = new ConversationV1({
  username: '<username>', // service username not your email!
  password: '<password>', // service password
  version_date: ConversationV1.VERSION_DATE_2017_05_26
});

conversation.message({
  input: { text: 'What's the weather?' },
  workspace_id: 'c9bfac7e-a7fa-4fe0-9b0d-e10f147209c8'
 }, function(err, response) {
     if (err) {
       console.error(err);
     } else {
       console.log(JSON.stringify(response, null, 2));
     }
});