Native program example

native_program.py

import sys
import struct
import socket
import json

class MyApp(object):
  def __init__(self):
      self.connection = socket.socket(shit I forgot the parameters)

  def main():
    while True:
      # Each message preceded by a 32-bit length
      length_encoded = sys.stdin.read(4)
      length = struct.unpack('=L', length_encoded)[0]

      body_bytes = sys.stdin.read(length)
      body = json.loads(body_bytes)
      response = self.handle_command(body)
      
      response_encoded = json.dumps(response)
      sys.stdout.write(struct.pack('=L', len(response_encoded)))
      sys.stdout.write(response_encoded)
   
  def handle_command(self, body):
    if body['action'] == 'purchase':
      self.connection.send('BUY %s %s %s', body['product_id'], body['cost'], body['credit_card']['cvv'])
      return {'purchase': 'OK'}
    if body['action'] == 'something':
      return {'something': 'something'}
    
    # shit, unrecognized command
    return {'status': 'err', 'error': 'wtf, unrecognized command'}
    
if __name__ == __main__:
  myapp = MyApp()
  myapp.main()