web service failure and recovery

[Iain]

Hi,

I am calling a web service from a PDA that returns a sizeable amount of
data. The connection the PDA gets to the net is very unreliable, and if
there is a connection problem half way though the PDA basically has to start
the download again.

Does anyone know of a good way to make this situation recoverable?

Is there any way to download from the web service in chunks, so that if a
chunk never arrives it can be requested again? E.g. download 100k at a time.

Thanks for your time
Iain