scripts/json_client.py

   1 #!/usr/bin/env python
   2 # -*- coding: iso-8859-15 -*-
   3
   4 import sys
   5 import socket
   6 import json
   7
   8 def set_keepalive(sock, after_idle_sec=1, interval_sec=3, max_fails=5):
   9         """Set TCP keepalive on an open socket.
  10
  11         It activates after 1 second (after_idle_sec) of idleness,
  12         then sends a keepalive ping once every 3 seconds (interval_sec),
  13         and closes the connection after 5 failed ping (max_fails), or 15 seconds
  14         """
  15         sock.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
  16         sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPIDLE, after_idle_sec)
  17         sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPINTVL, interval_sec)
  18         sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPCNT, max_fails)
  19 if not hasattr(socket, "set_keepalive"):
  20         socket.set_keepalive = set_keepalive
  21
  22 class JsonClient:
  23         def __init__(self, addr = ("arm", 10002)):
  24                 self.pSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
  25                 self.pSocket.settimeout(1)
  26                 socket.set_keepalive(self.pSocket)
  27                 self.pSocket.connect(addr)
  28                 self.lMsgs = []
  29
  30         def write(self, cmd):
  31                 data = {'command': cmd}
  32                 num = self.pSocket.sendall(json.dumps(data))
  33                 while True:
  34                         msg = json.loads(self.pSocket.recv(4096))
  35                         if msg.has_key("return"): return msg["return"]
  36                         elif msg.has_key("error"): return msg["error"]
  37                         self.lMsgs.insert(0, msg)
  38
  39         def read(self):
  40                 if len(self.lMsgs) > 0:
  41                         return self.lMsgs.pop()
  42                 self.pSocket.setblocking(False)
  43                 try:
  44                         return json.loads(self.pSocket.recv(4096))
  45                 except socket.error:
  46                         pass
  47                 finally:
  48                         self.pSocket.setblocking(True)
  49
  50 if __name__ == "__main__":
  51         print JsonClient().write(sys.argv[1])
  52
  53         #from datetime import datetime
  54         #from time import sleep
  55         #pClient = JsonClient()
  56         #while True:
  57         #       msg = pClient.read()
  58         #       if msg:
  59         #               print "Got async", msg
  60         #       print datetime.now(), float(pClient.write("get distance forward lower"))
  61         #       sleep(0.1)