Source code for cyclone.sse

# coding: utf-8
#
# Copyright 2010 Alexandre Fiori
# based on the original Tornado by Facebook
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.

"""`Server-sent events <http://en.wikipedia.org/wiki/Server-sent_events>`_
is a technology for providing push notifications from a server to a browser
client in the form of DOM events.

For more information, check out the `SEE demo
<https://github.com/fiorix/cyclone/tree/master/demos/sse>`_.
"""

from cyclone import escape
from cyclone.web import RequestHandler
from twisted.python import log


[docs]class SSEHandler(RequestHandler): """Subclass this class and define `bind` and `unbind` to get notified when a new client connects or disconnects, respectively. Once connected, you may send events to the browser via `sendEvent`. """ def __init__(self, application, request, **kwargs): RequestHandler.__init__(self, application, request, **kwargs) self.transport = request.connection.transport self._auto_finish = False
[docs] def sendEvent(self, message, event=None, eid=None, retry=None): """ sendEvent is the single method to send events to clients. Parameters: message: the event itself event: optional event name eid: optional event id to be used as Last-Event-ID header or e.lastEventId property retry: set the retry timeout in ms. default 3 secs. """ if isinstance(message, dict): message = escape.json_encode(message) if isinstance(message, unicode): message = message.encode("utf-8") assert isinstance(message, str) if eid: self.transport.write("id: %s\n" % eid) if event: self.transport.write("event: %s\n" % event) if retry: self.transport.write("retry: %s\n" % retry) self.transport.write("data: %s\n\n" % message)
def _execute(self, transforms, *args, **kwargs): self._transforms = [] # transforms if self.settings.get("debug"): log.msg("SSE connection from %s" % self.request.remote_ip) self.set_header("Content-Type", "text/event-stream") self.set_header("Cache-Control", "no-cache") self.set_header("Connection", "keep-alive") self.flush() self.request.connection.setRawMode() self.notifyFinish().addCallback(self.on_connection_closed) self.bind() def on_connection_closed(self, *args, **kwargs): if self.settings.get("debug"): log.msg("SSE client disconnected %s" % self.request.remote_ip) self.unbind()
[docs] def bind(self): """Gets called when a new client connects.""" pass
[docs] def unbind(self): """Gets called when an existing client disconnects.""" pass