server.js

let express = require("express");
let server = express()

let bodyParser = require('body-parser');

let multer = require('multer'); // v1.0.5
let upload = multer(); // for parsing multipart/form-data

// $npm install express body-parser multer --save

server.use(bodyParser.json()); // for parsing application/json
server.use(bodyParser.urlencoded({ extended: true })); // for parsing application/x-www-form-urlencoded

server.post("/", function (req, res)
{
    console.log(req.body);
});

server.listen(8080, function ()
{
    console.log("Listening on http://localhost:8080/");
});

stress_test.py

#!/usr/bin/env python

import requests
import json

URL = "http://localhost:8080/"
TIMES = 100

HEADERS = {"Content-Type": "application/json"}

PAYLOAD = {
    "messagetype": "GET_Shipments",

    "data":
    {
        "parameters":
        [
        	{
        		"type": "string",
        		"customer": "5555"
         	},

        	{
        		"number": "764928"
        	}
        ],

        "select":
        [
        	"idnum",
        	"nimi"
        ]
    }
}

for i in range(0, TIMES):
	r = requests.post(URL, data=json.dumps(PAYLOAD), headers=HEADERS)