Enviar POST desde JSON y recibirlo

sendpost.js

/****Cargar archivo JSON de clientes****/
var http = require('http');
var fs = require('fs');
var querystring = require('querystring'); 

fs.readFile('Clientes.json', 'utf8', function (err, data) {
  if (err) {    
    throw err; 
  }
  var objData = JSON.parse(data);
  hacerPost(objData);

});


function hacerPost(data){

   var collectionName = "personas"; 
  var post_options = {
    host: 'localhost',
    port: 3000,
    path: '/crearRegistros',
    method: 'POST',
    headers: {
      'Content-Type': 'application/x-www-form-urlencoded; charset = utf8'      
    }    
  }


  var post_data = querystring.stringify({
    "collection" : collectionName,
    'data' : data
  });

  post_options.headers['Content-Length'] = post_data.length;

  // Set up the request
  var post_req = http.request(post_options, function(res) {
      res.setEncoding('utf8');
      res.on('data', function (chunk) {
          console.log('Response: ' + chunk);
      });
  });

  post_req.on('error', function(e) {
    console.log('problem with request: ' + e.message);
  });

  post_req.write(post_data, 'utf8');
  post_req.end();

}

server.js

var express = require('express');
var http = require('http');
var path = require('path');
var mongo = require('mongoskin');
var mongouri = 'localhost:4000/mydb';  



var app = express();
app.use(express.bodyParser());



app.post("/crearRegistros", function(req, res){
  console.log("body: " , req.body);
  var doc = req.body;
  console.log('La colección es:',doc.collection);
  res.send("OK"); 
});


/*** config app.get***/
app.get('/people.json', function(request, response) {
  response.contentType('application/json');
  var db = mongo.db(mongouri,{safe:true});
  db.collection('personas').findOne({id:190}, function(error,result){
    if(error) throw error;   
    response.send(result);  //retorna registro encontrado
    console.log(result);
  });  
});



app.listen(3000);
console.log('listening to http://localhost:3000');