scenario-execution-server

Remote action execution for scenario-execution.
Actions declared with remote(host) run on a server process instead of locally.

Packages

Package	Role
scenario_execution_remote	Client-side OSC2 modifier + py_trees integration
scenario_execution_server	Server binary — executes action plugins on behalf of clients

Install

python -m venv .venv && source .venv/bin/activate
pip install -e scenario_execution/scenario_execution   # base library
pip install -e scenario_execution_remote
pip install -e scenario_execution_server

Usage

Start the server (on the machine that should execute actions):

# TCP
scenario_execution_server --port 7613

# Unix domain socket
scenario_execution_server --socket /tmp/se.sock

Declare a remote action in your .osc scenario:

import osc.types
import osc.helpers
import osc.remote

scenario test_run_process:
    do serial:
        run_process("hostname") with:
            remote("127.0.0.1")         # TCP, default port 7613
            # remote("192.168.1.10:9000")  # TCP, explicit port
            # remote("/tmp/se.sock")        # Unix domain socket

Run the scenario normally — the client connects to the server during tree setup:

scenario_execution test.osc -t

How it works

scenario_execution (client)          scenario_execution_server
        |                                       |
  setup()  ──── init + setup ────────────────► |  instantiates action plugin
  initialise() ─ execute ──────────────────── ► |  calls action.execute()
  update() ─────── update (poll) ─────────── ► |  returns RUNNING / SUCCESS / FAILURE
  terminate() ──── terminate ──────────────── ► |

Transport: ZMQ REQ/REP, serialisation: msgpack.
One socket per remote() modifier instance.
Connection timeout: 5 s (setup), 10 s (execution).

OSC2 modifier signature

modifier remote:
    endpoint: string  # hostname/IP, host:port, or /path/to/unix-socket

Any action available as a scenario_execution.actions entry-point on the server can be used remotely.

Deployment notes

Cross-machine use

Use TCP endpoints. Unix domain sockets (/path/...) are local-only.

remote("192.168.1.20")        # TCP — works across machines
remote("/tmp/se.sock")        # IPC — same machine only

The server must have:

• all required action Python packages installed (e.g. scenario_execution_ros)
• any files referenced by actions (launch files, configs, …) present at the same absolute paths as on the client, or accessible via a network mount

Kubernetes / sidecar pattern

Run scenario_execution_server as a sidecar container in the same pod and share a Unix socket via an emptyDir volume for zero-overhead IPC:

volumes:
  - name: ipc
    emptyDir: {}

Both containers mount /ipc and connect via remote("/ipc/se.sock").