Re: [hybi] Reliable message delivery (was Re: Technical feedback.)

[Maciej Stachowiak <[e-mail]>]

On Feb 1, 2010, at 4:00 PM, Thomson, Martin wrote:

>> If A wants to close the connection it does the following:
>> 
>> 1) transmits 0xFF 0x00 to B.
>> 2) Calls shutdown(SHUT_WR) on its socket (instead of close)
>> 3) Reads anything else transmitted from B until it gets EOF, at which
>> point it calls close().
>> 
>> When B receives 0xFF 0x00, it sends any remaining buffered messages and
>> calls close.
> 
> Anne's described solution works better.

How is it better? Can my solution lead to data loss?

> The 0xff00 frame is the indication that close() can be called safely.  Besides, it's two extra octets, hardly an imposition on either end.

It's not the octets that are wasteful, it's the extra round trip. The only material difference in my protocol is that the party responding to, rather than initiating the close doesn't have to send a special message, it just counts on the close initiator getting an EOF. Since the initiator has to stop sending after the close request, there's no risk of data loss in the other direction either (assuming I understand the TCP issue correctly.)

Regards,
Maciej