OTish: using short-term TCP connections to send to multiple slaves

[jkn]

Hi all
    This is a little bit OT for this newsgroup, but I intend to use python 
for prototyping at least, and I know there are a lot of knowledgeable 
people using Python in a Network context here...

I have a use case of a single 'master' machine which will need to 
periodically 'push' data to a variety of 'slave' devices on a small local 
subnet, over Ethernet. We are talking perhaps a dozen devices in all with 
comms occurring perhaps once very few seconds, to much less often - once per 
half an hour, or less. There is probably an upper bound of 64KB or so of 
data that is likely to be sent on each occasion.

Previous similar systems have attempted to do this by maintaining multiple 
long-term TCP connections from the master to all the slave devices. The 
Master is the server and the slaves periodically check the master to see 
what has changed. Although this ... works ..., we have had trouble 
maintaining the connection, for reasons ... I am not yet fully aware of.

We are now considering an alternative approach where the master maintains a 
list of slave devices and acts as a client. Each device is a server from the 
point of view of data transfer. We would then use a short-lived TCP 
connection when data is available; the Master would connect to each slave 
which needed the data, send it, and close the connection.

I should also add that we desire our system to be 'robust' in the face of 
situations such as cable unplugging, device power cycles, etc.

Although this might get round some of our current problems, I can see that 
we might end up with new problems to deal with. I am wondering if this 
scenario rings bells with anyone, and seeking pointers to what has been done 
elsewhere. As I say, I am expecting to prototype it in Python so any 
specifics also welcome!

(suggestions as to a better forum to ask for previous experience also 
gratefully received)

Thanks al lot for any thoughts/suggestions

    Jon N