[zeromq-dev] ZMTP/1.1, comments

Pieter Hintjens ph at imatix.com
Tue Aug 14 12:35:38 CEST 2012

On Mon, Aug 13, 2012 at 7:31 PM, Martin Hurton <hurtonm at gmail.com> wrote:

> I think there is a way how we can move from ZTP/1.0 toward a protocol
> with proper versioning and keep backward compatibility.
> We need to define a new VERSION bit in the flags field.

That is a nice idea...

> But I think we can use either share bit, which is use internally and
> seems that that one was always cleared, or MORE bit, which, it seems,
> was not set for greeting frame. This needs to be investigated.
> If neither of those bits can be used, we can still use some bit
> pattern that never occurred in the flag field in the past.


> disadvantages:
> - the support of older peers increases the latency of initial handshake
> - increases code complexity somewhat

Latency of initial handshake is irrelevant compared to the overhead of
creating a new TCP connection...

Code complexity is a shame but if it's localized, that's fine.

> What do you think? Is there something that would prevent the
> interoperability between old and new peers?

It sounds like a great plan. What we need next is working code that
shows this, and then we can update the ZMTP/1.1 RFC accordingly.

And then we'll finally have a versioned protocol in 0MQ :-)

Nice work, Martin.


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