One of the strengths of Tornado is it’s ability to handle asynchronous requests and support for websockets. Top make Mojo more of a responsive framework, we’ve decided to bundle TornadIO2 functionality as part of the overall package.
For those that do not know what TornadIO2 is, it is a SocketIO server implementation written in Python for Tornado, and makes it transparent to implement SocketIO clients into your app.
By default, Mojo will start a TornadIO server for you that multiplexes a channel connection for each of the apps in your project.
So if you have 2 apps: App1 and App2, then you will be able to speak to either of these apps via SocketIO on the client by connecting to the /App1Socket or /App2Socket channels in your client side configuration.
To configure what commands the server should intitiate on connection, send event or receive event, simply edit the socket_handlers.py file in your app folder:
from Mojo.SocketHandlers.BaseSocketHandler import MojoSocketHandler, CURRENT_SESSIONS, LOGGED_IN_SESSIONS
#Setup your socket connections here
class SocketConnectionHandler(MojoSocketHandler):
def on_message(self, msg):
#Do something cool when a message arrives
pass
To make the most of TornadIO2 and SocketIO we’d recommend you read the documentation for both as their inner workings fall outside of the remit of the Mojo documentation.
Mojo does some handy tracking for you if you use the MojoSocketHandler to manage your socket connections. Mojo will automatically register all connections in two variables that enable you to communicate with users directly from the start, these variables are CURRENT_SESSIONS and LOGGED_IN_SESSIONS
This is a dictionary object that will track each connection by their Session ID. The session ID is a secure Tornado cookie that is called session_id, if you are using the MojoSessionMixin module, this will be set for you, however if you want to roll your own session management, you can just set this cookie and the user will be tracked by the ID in the SocketHandler.
This will enable you to do something like:
from Mojo.RequestHandlers.MojoHandler import MojoRequestHandler
from Mojo.SocketHandlers.BaseSocketHandler import CURRENT_SESSIONS
import json
class HelloWorldHandler(MojoRequestHandler):
def get(self, *args, **kwargs):
jsonObj = json.dumps({'data':'%s has joined the chat' % (self.session_id)})
for session in CURRENT_SESSIONS:
session.emit('joinedStatus', jsonObj)
self.render('hello.html')
Although the above code is not functional, the principle is valid - in this example, you could use the CURRENT_SESSIONS object to broadcast to all active users that a new user has joined the conversation.
If you are using the AuthMixin from Mojo, then it will set an encrypted cookie of the name logged_in with the user ID of the current user. Naturally, you can set this yourself to whatever identifier you like if you decide not use the mixins.
Any session that is identified as Logged in will be added to the LOGGED_IN_SESSIONS dictionary, and will enable you to interact with users. In a similar vein to the CURRENT_SESSIONS object, you would now be able to send specific messages only to logged in members of your app.