https://github.com/DazWorrall/flask-sse

https://github.com/DazWorrall/flask-sse

Last synced: about 2 months ago
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• Host: GitHub
• URL: https://github.com/DazWorrall/flask-sse
• Owner: DazWorrall
• License: mit
• Created: 2012-10-18T16:33:20.000Z (almost 12 years ago)
• Default Branch: master
• Last Pushed: 2016-04-10T21:37:22.000Z (over 8 years ago)
• Last Synced: 2024-07-24T21:05:20.405Z (2 months ago)
• Language: Python
• Size: 11.7 KB
• Stars: 120
• Watchers: 6
• Forks: 23
• Open Issues: 0
• Metadata Files:
  • Readme: Readme.md
  • License: LICENSE

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README

        
Flask-Sse

=========

A simple [Flask][0] extension for HTML5 [server-sent events][1] support, powered by [Redis][2]

The extension provides 2 things - a blueprint with a single route for streaming events, and a helper function to send messages to subscribers:

    from flask import Flask, json

    from flask.ext.sse import sse, send_event

    

    app = Flask(__name__)

    app.register_blueprint(sse, url_prefix='/stream')

    

    @app.route('/send')

    def send_message():

        send_event('myevent', json.dumps({"message": "Hello!"}))

        

You can then subscribe to these events in a supported browser:

    

    

    

      

    

    

      

        var source = new EventSource("{{ url_for('sse.stream') }}");

        source.addEventListener('myevent', function(e) {

            var data = JSON.parse(e.data);

            // handle event

        }, false);

      

    

    

The source comes with a basic example

Clients can subscribe to different channels by setting 'channel' on the query string, which defaults to 'sse'. These correspond to redis channels.

    def send_message():

        send_event('myevent', json.dumps({"line": "Something happened"}), channel='logs')

    

    #######

        

    var source = new EventSource("{{ url_for('sse.stream', channel='logs') }}")    

    

Being a blueprint, you can attach a before_request handler to handle things like access control:

    @sse.before_request

    def check_access():

        if request.args.get('channel') == 'firehose' and not g.user.is_admin():

            abort(403)

Configuration

=============

Redis connection details are read from the applications config using the following keys (defaults in [])

* SSE_REDIS_HOST [localhost]

* SSE_REDIS_PORT [6379]

* SSE_REDIS_DB \[0\]

Caveats

=======

Subscribers will connect and block for a long time, so you should seriously consider running under an asynchronous WSGI server, such as gunicorn+gevent (like the example)

I should also say I'm not really maintaining this beyond accepting the odd pull request - it was built as an experiment but I'm not using it in anger on anything production. I wont be publishing it on PyPi myself for the same reasons - if I start using it properly then it will go on PyPi and have some tests put around it.

Credits

=======

Inspired by [django-sse](https://github.com/niwibe/django-sse)

[0]:http://flask.pocoo.org

[1]:http://en.wikipedia.org/wiki/Server-sent_events

[2]:http://redis.io/