21 May 2002 Status report -------------------------- >I think the file-transfer should send backward confirmation >handshakes, yes, but I *don't* think that "block N" should be held >up in the transmitter until "block N-1" is confirmed (I believe >FTP does it this way). So, the transmitter sends data, the receiver >confirms receipt, and the transmitter verifies that it got a >receipt for every block when it's done. If necessary, at the end >of the transfer, the transmitter resends the block(s) it didn't get >a confirmation for. >Doable?
I am afraid, no. At least as it is stated here. The main objection is that doing so, we will duplicate the functionality provided by TCP/IP stack. What are we going to do with the "blocks" N, N+1, :? We'll have to prestore them in order to glue afterwards. That's what TCP does! The problem is *not* the one of loosing some blocks from the meddle as they go, but that some critical error may occur on receiver that prevents it from getting the rest of the transfer. It could be, for example, lack of room. From this point of view, the best way out could be: 1 sender sends blocks without waiting for confirmation (as you have suggested), 2. sender listens at the same time for a error message from receiver. Once such message has come, the transfer stops and revokes. 3. In the end of transfer, receiver sends back a success message. On that message, sender closes socket and tells the user that it's all right. Q: How long must the sender wait for the success confirmation message to come after the last block has been sent? Is a time out needed? Why, the receiver may have died after all. And how about the progress bar? I guess, it begins to show 100% once the last block has gone but the final OK message pops up upon success confirmation only (well, it may be not a pop-up but some other event instead - does not matter). On time out expiration, a error box pops up. How about that? -Oleg _______________________________________________________________ Don't miss the 2002 Sprint PCS Application Developer's Conference August 25-28 in Las Vegas -- http://devcon.sprintpcs.com/adp/index.cfm _______________________________________________ Kaboodle-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/kaboodle-devel
