Re: [Cerowrt-devel] real time text

[Michael Richardson <mcr@sandelman.ca>]

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David P. Reed <dpreed@deepplum.com> wrote:
    > Then use on that logic a sort of erasure coding (allowing
    > reconstruction of packets containing backspace/delete) that allows
    > out-of-order delivery as information becomes known. Erasure coding
    > (like Digital Fountain codes) are more efficient than retransmission of
    > duplicates of packets - if there are N packets queued in the network,
    > you'd need some kind of SACK-like scheme, but SACK doesn't work very
    > well when the buffering is a backup in the network, rather than in the
    > receive endpoint's OS queueing. Digital Fountains or its successors
    > work great! (and I think the patent expired finally).

I was reading the wikipedia entry on Fountain_code, because I didn't know
what that was.  I didn't know the IETF had published RaptorQ.
I have only read a page or two of the two RFCs.

While I understand that one could do this to megabyte-sized things,
but I'm unclear if all symbols have to be received before some pieces can be
extracted.  I'm specifically thinking about being able to broadcast firmware
updates to many (IoT) devices at the same time, and for the devices to be
able to not store the codes, just the results into flash.

I can well imagine that due to the FEC, that receipt of a single symbol would
could cause updates to many parts of the image, but I wanted to know if
all the received symbols had to be retained until the end?

--
]               Never tell me the odds!                 | ipv6 mesh networks [
]   Michael Richardson, Sandelman Software Works        |    IoT architect   [
]     mcr@sandelman.ca  http://www.sandelman.ca/        |   ruby on rails    [


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