[zeromq-dev] encoder::has_data() method deprecated?

Martin Hurton hurtonm at gmail.com
Tue Mar 18 10:49:17 CET 2014


Hi Brian,

Nice work.
No problem introducing has_data member function.
Another option, I think, would be to rely on the fact that encode member
function returns 0 when there are no data pending in the encoder.

- Martin


On Fri, Mar 14, 2014 at 11:43 PM, Brian Adamson
<brian.adamson at nrl.navy.mil>wrote:

> Hello,
>
> I had ported our NACK-Oriented Reliable Multicast (NORM, RFC 5740)
> protocol implementation into a copy of the libzmq 4.0.3 source tree and it
> working with some test code implemented with the "pyzmq" API.   However, in
> the past couple of days, using the latest code from GitHub in order to
> provide a candidate submission of this capability, I found that the
> "encoder::has_data()" method was no longer available.  It had been used in
> the "stream_engine" code and I was using it in my "norm_engine" code.
>
>  I used it because NORM has a mechanism for marking application-defined
> message boundaries so that late-joining receivers can easily "synchronize"
> to sender transmission streams and recover application-defined message
> boundaries.  So I used the "encoder::has_data()" to know when the last byte
> of the message had been "encoded" and written to the NORM transmit stream
> for the NormStreamMarkEom() function to be applied that invokes the message
> boundary capability.
>
> I started to implement a work-around based on the "msg::size()" and
> counting bytes written to the stream, but that means knowing/determining
> the encoder overhead (i.e. flags, length fields, etc) and I want to be more
> forward-looking than that since the NORM transport can potentially be
> applied to more ZeroMQ socket types and purposes than what I've done so far.
>
> So, my question is if I should re-implement the encoder::has_data() method
> or if there is a better approach.  In my fork, I've done this and verified
> that the "norm_engine" works as it did with the libzmq 4.0.3 code, but
> Pieter has wisely suggested I put this question to the list.
>
> Also, I have a short overview/write-up of what I've done with ZeroMQ/NORM
> that I can post to the list if there's interest? And about as soon as this
> issue can be resolved, I can issue a pull request for this "norm_engine"
> code as well.
>
> best regards,
>
>  Brian Adamson
> brian.adamson at nrl.navy.mil
>
>
>
>
>
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>
>
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