Would it help to read some of the Internet RFCs? They deal with this kind of things in various ways.
Not that they're concerned with Objective-C or Cocoa but the concepts might be useful. On 6/8/15, Graham Cox <[email protected]> wrote: > I have the following task I need to implement. > > > 1. I have a queue of NSData objects, usually representing a continuous > stream, but delivered in variable-sized chunks. However some chunks could be > missing, but the queue represents the correct order of the stream that was > delivered, and the missing chunks can be flagged. > > 2. The data in the stream consists of packets of fixed length. I need to > extract the packets and pass them as complete single entities to another > object (a delegate) for further processing. All complete packets must be > extractable, and I’d like to do this on a secondary thread if possible. > > 3. Due to the possibility of missing data chunks, resynchronisation for each > new data may be required. I can detect when a data entry is contiguous with > the previous one, or when one or more chunks has been skipped. A packet may > be split across input data, or may be incomplete due to being split across > data where the second part was missing. > > 4. Packet detection is based on a signature byte at the start of each > packet, and the fixed length of the packet which is a few hundred bytes. If > five consecutive packets are detected having the same signature byte, the > packets are presumed to have been detected and can be extracted for > processing. > > The object that handles this should accept NSData chunks as input and queue > them, or if there is a missing chunk, a nil data object. The object’s > delegate should be passed the extracted packets one at a time in order as > they become available, again as NSData objects. No time synchronization > between the input and output is required. > > This sort of processing isn’t really my strong point, so while I can think > of various ways to solve it by brute force and ignorance, I would have > thought this is something that would be recognisable as a standard sort of > stream processing algorithm by those who’ve done it before. Even just an > outline or pointer to something like this would be a help. > > > —Graham > > > > _______________________________________________ > > Cocoa-dev mailing list ([email protected]) > > Please do not post admin requests or moderator comments to the list. > Contact the moderators at cocoa-dev-admins(at)lists.apple.com > > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/cocoa-dev/mdcrawford%40gmail.com > > This email sent to [email protected] -- Michael David Crawford, Consulting Software Engineer [email protected] http://www.warplife.com/mdc/ Available for Software Development in the Portland, Oregon Metropolitan Area. _______________________________________________ Cocoa-dev mailing list ([email protected]) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [email protected]
