Re: Broadcast server
- From: "Matt Hammond" <matt.hammond@xxxxxxxxxxxx>
- Date: Thu, 31 Aug 2006 12:33:56 +0100
On Thu, 31 Aug 2006 10:14:15 +0100, <swell@xxxxxxxxxxxxxxx> wrote:
I would like to write a server with the low level API of python (
socket+select and/or socket+thread ) that allow me to register client
and update them every X seconds ( could be the time, the temperature, a
stock quote, a message , ... ).
How to write the server that keep hot connections with clients and
update them when events are trigerred. I don't know how to begin this ,
i look at the python doc but the doc is more related to client updating
the server and i am not sure of the right design that could be use
here.
Kamaelia ( http://kamaelia.sf.net/ ) - the project I'm working on, feels like it may be well suited to this kind of task. Its based around having individual components that pass messages to each other. So you can envisage an event source propogating a message to all subscribed clients quite easily.
Your source's of events can be components, that publish their events to a 'backplane' - a kind of distribution board that replicates messages sent to it to all subscribers.
from Axon.Component import component
from Kamaelia.Util.Backplane import Backplane, subscribeTo, publishTo
from Kamaelia.Util.PipelineComponent import pipeline
class EventSource(component):
def main(self):
while 1:
if event_happens:
self.send( "EVENT HAPPENED!\n", "outbox")
yield 1
pipeline( EventSource(),
publishTo("Events"),
).activate()
Backplane("Events").activate()
You can have any number of event sources, all 'publishing' to the same backplane.
Then to handle clients connecting I'd create a server component, with a factory function that creates a component to handle each client connection. In this case, a component that 'subscribes' to messages coming from the backplane:
from Kamaelia.Chassis.ConnectedServer import SimpleServer
def clientHandlerFactory():
return subscribeTo("Events")
SimpleServer(clientHandlerFactory).activate()
Then I'd start the system running:
from Axon.Scheduler import scheduler
scheduler.run.runThreads()
Things like the client handling could be extended relatively easily to marshall complex data types to strings, suitable for network transmission; or to manage clients choosing what data sources to subscribe to.
If you think this approach might work for you, I'm happy to give you a hand with getting Kamaelia up and running, and with learning how to write your own components to make the system more sophisticated.
We hang about on #kamaelia on freenode (irc) - please do drop in for a chat!
Hope this helps!
Matt
--
| Matt Hammond
| Research Engineer, Tech. Group, BBC, Kingswood Warren, Tadworth, Surrey, UK
| http://kamaelia.sf.net/
| http://www.bbc.co.uk/rd/
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