Re: [hybi] thewebsocketprotocol #28 (new): Fragmentation

[Zhong Yu <[e-mail]>]

On Mon, Nov 22, 2010 at 1:09 PM, John Tamplin <[e-mail]> wrote:
> On Mon, Nov 22, 2010 at 1:32 PM, Zhong Yu <[e-mail]> wrote:
>>
>> I think the answers to this question depend on specific programming
>> models, therefore they are best addressed by applications/frameworks.
>> WS protocol doesn't have to support streaming - that's the job of
>> frameworks. A single layer shouldn't mix streams and messages. (So we
>> have streaming framework, on top of WebSocket frames, on top of TCP
>> stream, on top of IP frames, on top of electronic stream, on top of
>> quantum of photons... It's turtle all the way, but there is only one
>> turtle at each level)
>
> I disagree completely.  WebSocket fragmentation isn't about supporting
> streams but rather supporting senders that don't know the length up front

if fragments of a single message must be consecutive and there cannot
be gaps between, then it is equivalent to in-frame chunking. That
sounds simple and fine.

> and advanced uses such as multiplexing.

for example?

> The unit of communication via
> WebSocket is always a message.
> This question has to be answered in order to interpret a stream of frames
> properly.  One of the following must be true to have a single unique
> interpretation of a sequence of frames:
> - control frames can't be fragmented
> - control frames cannot be inserted in the middle of a fragmented message
> - there must be a way to differentiate a control fragment from a data
> fragment
> - the receiver must keep an arbitrarily deep stack of in-progress messages
> --
> John A. Tamplin
> Software Engineer (GWT), Google
>