P2P Protocol Definition
DISCOVERY
Use JmDNS for discovery. The service type you should use is
"_cs6452._tcp.local."
There is still a bit of flakiness in JmDNS. In particular, sometimes requests to
resolve a service aren't handled. It's fairly easy to work around this. In my version
of the code, did the following:
- When you first detect a service (through serviceAdded), fire off requestServiceInfo
to try to resolve the service. Also, add an entry to a dictionary where the name of
the service is the key, and the value is a new Date object that provides a timestamp
on when the request was sent:
self.jmdns.requestServiceInfo(event.type, event.name, 5000)
self.pendingRequests[event.name] = util.Date()
- In our serviceResolved method, remove entries from this dictionary once they are
resolved:
del self.pendingRequests[event.name]
- Create a new thread that will wake up periodically and check for services that are
still in this list, and have a timestamp that is older than, say, 10 seconds ago.
Reissue requests for these to be resolved.
self.jmdnsMender = threading.Thread(target=self.mendJmdns)
self.jmdnsMender.start()
def mendJmdns(self):
while 1:
time.sleep(10) # wake up every 10 seconds
for key, value in self.pendingRequests.items()
now = util.Date()
if now.time - value.time > 10000: # milliseconds
self.jmdns.requestServiceInfo("_cs6452._tcp.local.", key, 5000)
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PROTOCOL BASICS
Each request should open a new connection to the peer, send a correctly formatted
