Re: [rtcweb] Sending of zero-length messages over data channels

[Justin Uberti <[e-mail]>]

Changing the send() API defeats the purpose of trying to provide full
WebSockets compatibility.

I think the PPID_EMPTY approach (probably PPID_EMPTY_TEXT and
PPID_EMPTY_BINARY, to be precise) is a simple and complete solution.


On Wed, Jul 23, 2014 at 8:00 AM, Makaraju, Maridi Raju (Raju) <
[e-mail]> wrote:

>
>
> In the existing data channel protocol, it's not possible to send
> zero-length messages, because SCTP prohibits it.
>
>
>
> While this may seem to be an academic point, it does represent a
> divergence from WebSockets, and this difference could be meaningful to
> applications who use empty messages for keepalives. Or maybe the Yo app.
>
>
>
> Since we can't send a zero-length SCTP message, I propose we add a
> PPID_EMPTY value or something similar to indicate a message with empty
> content.
>
> *[Raju] There is a genuine need for this and the proposal is good. *
>
> *However, I am thinking of an alternate proposal to achieve the same but
> in a generic way. *
>
> *Define a PPID_OOB (out of band) or something similar.*
>
> *Apps can use this to send a message of non-zero length. For the “Yo” kind
> of app or empty stream-level heartbeat purpose, app can send a 1 byte
> length message, which other end’s app ignores.*
>
> *This approach involves bit more API work for webrtc to have a variation
> of send(data, oobFlag) and new data type in onmessage(). IMHO, this
> approach allows more possibilities in future and also the same approach can
> be used by other SCTP use cases not involving webrtc.*
>
>
>
> *BR*
>
> *raju*
>