Remote Procedure Calls
Requirements
Establishing a connection
Python
import os
import signal
from autobahn.asyncio.component import Component
from autobahn.asyncio.component import run
BONDY_URL = os.getenv("BONDY_URL", "ws://localhost:18080/ws")
REALM = os.getenv("REALM", "com.example.realm")
AUTHMETHOD = os.getenv("AUTHMETHOD", "anonymous")
AUTHENTICATION_CONFIG = {"anonymous": None}
class Connect:
# Creation of the autobahn component
def __init__(self):
transport = {
"type": "websocket",
"url": BONDY_URL,
"serializers": ["json"],
}
auth_config = AUTHENTICATION_CONFIG[AUTHMETHOD]
self._component = Component(
transports=[transport],
authentication=auth_config,
realm=REALM
)
# Register session lifecycle callbacks
self._component.on("join", self._on_join)
self._component.on("leave", self._on_leave)
self._session = None
def start(self):
run([self._component])
print("Done.")
def _on_join(self, session, details):
self._session = session
def _on_leave(self, session, details):
self._session = None
# Start of the script when called from prompt
if __name__ == "__main__":
# Handle Ctrl+C gracefully
def signal_handler(sig, frame):
sys.exit(0)
signal.signal(signal.SIGINT, signal_handler)
connect = Connect()
connect.start()How Registrations Work
Basic Registrations
Typically, you will place you procedure registration on the session's on_join callback, that way as soon as the session has been established your component will register the procedures it offers.
In the following snippet we register the procedure com.example.add which takes two integers as arguments.
Python
async def _on_join(self, session, details):
self._session = session
self._session.register(self.add, "com.example.add")
# Call handler for procedure 'com.example.add'
def add(self, x, y):
"""Add 2 numbers."""
try:
z = float(x) + float(y)
except Exception as error:
print(f"Invalid input: {error.args[0]}")
raise
else:
return zMaking a Call
Python
# The user provides and input for x and y
try:
z = await self._session.call("com.example.add", x, y)
except Exception as error:
print(f"RPC failed: {error.args[0]}")
else:
print(f"{x} + {y} = {z}")