socket.recv is empty but the result is showing in Maya

Question

I am trying to get values for the rotation of joints in Maya into an external IDE. I have successfully been able to send commands and Maya responds properly but I am having trouble understanding how to receive the results back in the IDE.

I have tried using socket.recv and socket.recvmsg but got errors for both.

Code running in PyCharm

import socket
host = 'localhost'
port = 7720

code1 = ("servo_1 = [cmds.getAttr('joint2.rotateY')]\\n"
         "print servo_1")
try:
   # Connect to Maya Command Port
   maya = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
   maya.connect( (host,port) )
   # Send Command Through Socket --> Can Only Send MEL Commands
   message = 'python("{}")'.format(code1)
   print message
   maya.send(message)
   reply = maya.recv(4096)
   print reply
except:
   raise Exception, 'Connection Failed To : %s:%s' % (host, port)

finally:
   #Close Socket Connection
   maya.close()

Code in Maya to open the commandPort

import maya.cmds as cmds
if not cmds.commandPort(':7720', q=True, echoOutput=True, noreturn=False):
    cmds.commandPort(name=':7720')

The expected output is [43.74] as is shown in Maya but the actual output in PyCharm

Answer 1

I got it to work by setting up a client socket connection from Maya to PyCharm making a python socket server and setting up maya as the client and using the pickle module to send a list.

Python Server

import socket
import pickle

HOST = 'localhost'
PORT = 50007
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((HOST, PORT))
s.listen(1)
conn, addr = s.accept()
print 'Connected by', addr
while 1:
    data = conn.recv(4096)
    if not data: break
    conn.send(data)
    data2 = pickle.loads(data)
    print 'servo_1 = %s' % (data2)
conn.close()

Maya Client

import socket, pickle
import maya.cmds as cmds

HOST = 'localhost'
PORT = 50007
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((HOST, PORT))

max = int(cmds.playbackOptions( q=True, aet=True))
servo_1 = [cmds.getAttr("joint2.rotateY")]

data_string = pickle.dumps(servo_1)
s.send(data_string)

data = s.recv(4096)
data_arr = pickle.loads(data)
s.close()
print 'Received', repr(data_arr)

Answer 2

CommandPort is meant for sending commands rather than retrieving output, there's still a way to do it: the trick is you need to send each command and receive output separately: https://forums.cgsociety.org/t/telnet-or-socket-no-result-back-from-maya/1730817/2

But the smart way to do is using maya.api.OpenMaya MCommandMessage message callback to stream output that maya received; So basically, a server (editor) client (maya) to send command, and another client (editor) server to stream output. This is how plugin's like MayaCharm (for PyCharm) and MayaSublime (for Sublime) work, and this is what I ended up choosing after some research. See detail examples: https://www.xingyulei.com/post/maya-commandport/ https://www.xingyulei.com/post/maya-streaming/