Channelstream

This is a websocket-based communication server for python applications, your applications communicate with it via simple JSON REST API.

Visit http://channelstream.org for more information.

Installation and Setup

Obtain source from github and do:

YOUR_PYTHON_ENV/bin/pip install channelstream

Generate new configuration:

YOUR_PYTHON_ENV/bin/channelstream_utils make_config -o config.ini

Start the server:

YOUR_PYTHON_ENV/bin/channelstream -i config.ini

The server can be configured via ini files (channelstream -i filename), example:

Demos

This repository provides demonstrative applications on how to connect with the server and send information to clients.

You have a simple notification demo built on flask:

cd demo/notification/
YOUR_PYTHON_ENV/bin/pip install flask
YOUR_PYTHON_ENV/bin/flask run

Now you can open multiple browser windows to http://127.0.0.1:5000/ and test notifications.

There is also more complex chat application demo included, it showcases multiple channel subscriptions, message edits and user state changing.

YOUR_PYTHON_ENV/bin/python demo/chat/app.py

Open your browser and point it to following url:

http://127.0.0.1:6543

To run the demo you will need to have the requests package installed in your environment.

Security and communication model

Channelstream provides API explorer that you can use to interact with various endpoints, it is available by default under http://127.0.0.1:8000/api-explorer.

To send information client interacts only with your normal www application. Your app handled authentication and processing messages from client, then passed them as signed message to channelstream server for broadcast.

websocket client -> webapp (security and transformation happens here) -> REST call to socket server -> broadcast to other clients

This model is easy to implement, secure, easy to scale and allows all kind of languages/apps/work queues to interact with socket server.

All messages need to be signed with a HMAC of destination endpoint ::

import requests
from itsdangerous import TimestampSigner
signer = TimestampSigner(SERVER_SECRET)
sig_for_server = signer.sign('/connect')
secret_headers = {'x-channelstream-secret': sig_for_server,
                  'Content-Type': 'application/json'}
response = requests.post(url, data=json.dumps(payload),
                         headers=secret_headers).json()

Data format and endpoints

Please consult API Explorer (http://127.0.0.1:8000/api-explorer) for in depth information about endpoints.

Some examples:

• /connect POST connects users to the server
• /subscribe POST Subscribes connection to new channels
• /unsubscribe POST Removes connection from channels
• /user_state POST set the state of specific user
• /message POST Send message to channels and/or users
• /message DELETE Delete message from history and emit changes
• /message PATCH Edit existing message in history and emit changes
• /channel_config POST Set channel configuration
• /info POST Returns channel information

Client API

• /ws GET Handles websocket connections
• /listen GET Handles long polling connections
• /disconnect GET Permanently remove connection from server
• /disconnect POST Permanently remove connection from server

Admin API

• /admin/admin.json GET Return server information in json format for admin panel purposes
• /admin/admin.json POST Return server information in json format for admin panel purposes

Responses to js client

Responses to client are in form of list containing objects:

examples:

new message ::

{
"date": "2011-09-15T11:36:18.471862",
"message": MSG_PAYLOAD,
"type": "message",
"user": "NAME_OF_POSTER",
"channel": "CHAN_NAME"
}

presence info ::

{
"date": "2011-09-15T11:43:47.434905",
"message": {"action":"joined/parted"},
"type": "presence",
"user": "NAME_OF_POSTER",
"channel": "CHAN_NAME"
}

Currently following message types are emited: message, message:edit, message:delete, presence, user_state_change.