Here's Lukas response (from the OS Synthesis list): ------------------------------------------------------------ What our SyncML clients do is timing out the wait for data after a 5 minutes or so, and then run a retry (send same message again). Servers should be able to handle that - Nokia started doing this years ago as a way to increase stability. Our server simply buffers the last response, and when it receives a message it detects as a resend of an already answered message (by MsgID), it just re-sends the buffered response. The timeout could also be shorter, because especially SonyEricsson clients exist that have very little patience (around 30 secs), so again, servers will ensure that they can answer within 30 secs. Our server has one operation that could take longer for huge datasets (loading the sync set for a slow sync), and solves the problem by sending "empty" responses (just non-<final/>, with Alert 222 when needed) at least every 30 seconds (configurable, of course :-) while the sync set loading is in progress. This approach has proven robust, we did many tests with ripping a device out of it's USB cradle connection in mid-sync and when wireless network was established the sync session continued on a new connection, of course with some retries (message resends). ------------------------------------------------------------- We should implement something similar.