We can’t entirely stream from the files because we need to encrypt the data.
Any thoughts on using multiple threads rather than one? Or using the GPU to encrypt/decrypt the data? I lean towards using a single thread unless the performance becomes limited by the encryption/decryption work, then multiple threads might help... On Jan 10, 2019, at 9:58 AM, Quinn The Eskimo! <eski...@apple.com<mailto:eski...@apple.com>> wrote: On 10 Jan 2019, at 15:42, Howard Shere <howard.sh...@synchronoss.com<mailto:howard.sh...@synchronoss.com>> wrote: Lots of files. That’s likely to be the most interesting part of this. Transferring a single large file over Wi-Fi is pretty straightforward: Open a TCP connection and pour bytes down it. That’ll be fast and work well in a wide variety of network environments. You may be able to do better with a custom transport protocol in some specific environments, but it’s hard to do better than TCP in general. If you go down this path it’s a good idea to start the transfer with a header (including, at a minimum, the expected length) and end the transfer with a checksum. IMPORTANT: You need an end-to-end checksum because, when transferring /large/ amounts of data, the probability of an error not being detected by the TCP checksum starts to rise. The header will also allow you to support resumable transfers, which is always a good idea on iOS. The specific API you use for this doesn’t really matter than much. If you had a minimum deployment target of iOS 12 I’d recommend `NWConnection` but, as you have to support older systems, using `NSStream` is fine. If you have multiple files to transfer then things get substantially more complex. Ideally you’d want to transfer all the files over the same TCP connection. The thing you want to avoid is an archive-transfer-unarchive approach, because the time taken for the [un]archiving could be significant. That means the sender needs to stream off the file system and on to the network, and the receiver needs to do the reverse. This isn’t too hard but the devil is in the details. For example, supporting resumable transfers with multiple files is going to be tricky. You could probably find an industry-standard protocol that meets your needs, but that’s not always a win. A lot of the time standard protocols tend to be more complex than necessary, and they’re only an advantage if you can find a library that implements the protocol, and that brings its own complexities. Share and Enjoy -- Quinn "The Eskimo!" <http://www.apple.com/developer/> Apple Developer Relations, Developer Technical Support, Core OS/Hardware _______________________________________________ Do not post admin requests to the list. They will be ignored. Macnetworkprog mailing list (Macnetworkprog@lists.apple.com<mailto:Macnetworkprog@lists.apple.com>) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/macnetworkprog/howard.shere%40synchronoss.com This email sent to howard.sh...@synchronoss.com Howard Shere | Software Sculptor Desk: +1 CAL.LMO.BILE | Mobile: +1 901.359.4200 howard.sh...@synchronoss.com<mailto:howard.sh...@synchronoss.com> www.synchronoss.com<http://www.synchronoss.com>
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