[Twisted-Python] twisted and gprs networks

Carl Zmola zmola at acm.org
Sun Jan 7 09:56:37 MST 2007


 From my experience with mobile devices, you will need to do a little 
more work than just using TCP/IP or UDP for this. Sockets work well if 
the communication is reliable, but if the connection goes down regularly 
you will need to think about different ways of doing this.

I would suggest assigning each PDA a unique name (at the PDA device).  
Your GPRS device should have an ID that will serve this purpose.

It will be up to the PDA to reconnect the socket when the network 
becomes available again.

The server can do the mapping by the devices ID number.


John Aherne wrote:
> I am looking at using PDA devices talking to a server over gprs.
> I need to push data to the PDA over elapsed timeframes that might be 
> hours. Naturally during this timespan the device may have been dropped 
> from the network or acquire a different IP address.
> However to push data to the PDA, I need to record the IP and port used 
> by the PDA for its first contact since it is stuck behind a firewall.
> The socket needs to be kept open on the PDA so the server can keep 
> responding on the same session over a period of time.
> Using straight sockets I can do this by holding the reference to the 
> IP/port used by the PDA. And checking every now and then that the 
> connection is still valid. But I am no comms expert and I need to keep 
> track of over 100 devices and keep reliably sending messages to them 
> at random intervals.
> So, I thought it might be better to use some framework for the server 
> since I am no expert on sockets.
> But looking through the docs for twisted and some of the code, I can't 
> see anywhere how I can get and use a reference to the port and reuse 
> the open session on the PDA.
> Can I do this with twisted or should I look for some other way of 
> doing what I want.
> I was thinking I could use irc with twisted but not sure if I am 
> barking up the wrong tree.
> Thanks for any ideas of solving the problem.
> John Aherne
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