Pysher

Warnings

• breaking Prior to v1.0.7, callback functions bound to events or connection binds might have received an incorrect number of arguments. Version 1.0.7 fixed this to match the expected argument signature, which could break existing code that relied on the old, incorrect argument count for `my_func(*args, **kwargs)` or similar callbacks.
  Fix: Review all callback functions bound to Pusher events or connection lifecycle events (e.g., `pusher:connection_established`) and adjust their signatures to correctly handle the arguments passed by Pysher 1.0.7+.
• gotcha Pysher has specific compatibility requirements with its `websocket-client` dependency. `websocket-client==0.49` is explicitly excluded in `setup.py`, and issues have been reported with `websocket-client==0.58.0` and `Pysher 1.0.6`. Always refer to the `install_requires` in `setup.py` or the official GitHub README for the exact compatible versions.
  Fix: Ensure your `websocket-client` version adheres to Pysher's `install_requires` specifications. If issues arise, try downgrading or upgrading `websocket-client` to a known compatible version.
• gotcha Pysher dropped support for Python versions prior to 3.5. Attempting to use Pysher on older Python 3 releases (e.g., 3.4 or 2.x) will result in compatibility errors.
  Fix: Ensure your project is running on Python 3.5 or newer.
• gotcha The Pysher library is explicitly stated to be in 'maintenance mode'. This implies that while bug fixes and contributions (PRs) are welcome and released, active development of new features or rapid updates should not be expected.
  Fix: Set realistic expectations for new features and be prepared to contribute fixes or features via pull requests if needed.
• gotcha For optimal performance, especially when handling high volumes of messages, it is recommended to install the `wsaccel` package. This allows the underlying `websocket-client` to utilize C-compiled UTF-8 validation methods, which are significantly more CPU-efficient than the default pure Python implementation.
  Fix: Install `wsaccel` alongside Pysher: `pip install pysher wsaccel`.

Install

• pip install pysher Install Pysher

Imports

• Pusher

  import pysher
  pusher = pysher.Pusher(...)

Quickstart

This quickstart demonstrates how to connect to Pusher, subscribe to a channel, and bind a callback function to an event. It includes basic logging to observe the connection process and uses environment variables for the Pusher App Key for secure credentials handling.

import pysher
import os
import time
import logging

# Configure logging to see Pysher's internal communication
root = logging.getLogger()
root.setLevel(logging.INFO)
ch = logging.StreamHandler()
root.addHandler(ch)

# Replace with your actual Pusher App Key and Cluster
APP_KEY = os.environ.get('PUSHER_APP_KEY', 'your_app_key')
CLUSTER = os.environ.get('PUSHER_CLUSTER', 'mt1') # e.g., 'mt1', 'eu', 'ap1'

if APP_KEY == 'your_app_key':
    print("WARNING: Please set PUSHER_APP_KEY environment variable or replace 'your_app_key' in the code.")

def my_func(*args, **kwargs):
    """Callback function to process messages from a subscribed event."""
    print(f"Processing Args: {args}")
    print(f"Processing Kwargs: {kwargs}")

def connect_handler(data):
    """Callback function when connection is established."""
    print(f"Connected to Pusher! Connection data: {data}")
    # Subscribe to a channel after successful connection
    channel = pusher.subscribe('my-channel')
    # Bind a callback to a specific event on that channel
    channel.bind('my-event', my_func)
    print("Subscribed to 'my-channel' and bound 'my-event'.")

# Initialize Pusher client
pusher = pysher.Pusher(APP_KEY, cluster=CLUSTER)

# Bind the connect handler to the 'pusher:connection_established' event
pusher.connection.bind('pusher:connection_established', connect_handler)

# Connect to Pusher
print("Connecting to Pusher...")
pusher.connect()

try:
    while True:
        # Keep the main thread alive to allow websocket client to run
        time.sleep(1)
except KeyboardInterrupt:
    print("\nDisconnecting Pysher.")
    pusher.disconnect()
    print("Disconnected.")