Operate Maya from an external Python interpreter using the rpyc module

This article is the 23rd day article of Takumi Akashiro Alone Advent Calendar 2020.

At the beginning

When I touched Houdini before, I thought that the hrpyc module that manipulates Houdini's hou object from external Python was amazing ... [^ 1]. With reference to hrpyc, I wondered if I could write something similar in Maya, so I made it.

[^ 1]: I haven't actually used it just because I think it's amazing.

What is the rpyc module?

** R ** emote ** Py ** thon ** C ** all, a module for using Python objects from another process. [^ 2]

The caller can use a Python object in another session by setting up a server and providing the callee with a proxy for the object over the network. I'll leave the details to rpyc · PyPI, but hrpyc used in Houdini is a very simple wrapper for rpyc.

[^ 2]: There are various theories

How to use

1. Install rpyc with pip install rpyc -t <Maya's Script folder>.
   There is no binary, so any python2 system should be okay ...
2. Save the following files in the Maya Script folder.

mrpyc.py

#! python2
# encoding: utf-8

import threading

from rpyc.utils import classic
from rpyc.core import SlaveService
from rpyc.utils.server import ThreadedServer

PORT = 18812

def _start_server(port=PORT):
    t = ThreadedServer(
        SlaveService,
        hostname = '0.0.0.0', port = int(port),
        reuse_addr = True, authenticator = None,
        registrar = None, auto_register = False
        )
    t.start()


def start_server(port=PORT):
    thread = threading.Thread(target=lambda: _start_server(port))
    thread.start()
    return thread


def import_remote_maya_module(server="127.0.0.1", port=PORT):
    return classic.connect(server, port).modules['maya']

3. Set up a Maya server by executing the following with Maya's Script Editor.

import mrpyc
mrpyc.start_server()

4. Execute the following with an external interpreter to get the maya module and try to make a polyCube.

import mrpyc
maya = mrpyc.import_remote_maya_module()

maya.cmds.polyCube()

Tightening

It was easy [^ 3] other than that!

It just feels like an experiment, and after a few minutes the connection dies or Maya crashes, so It may be safe to implement it by referring to _RemoteHouAttrWrapper of hrpyc.

[^ 3]: When I felt it touched, I made it by scraping off the extra part from hrpyc.py, and it took about 3 hours.