[zeromq-dev] how to hook ZMTP to prepend outputs and trim inputs ?

Pieter Hintjens ph at imatix.com
Fri Jan 17 15:30:02 CET 2014


You can't add to a message without breaking ZMTP. What you could
conceivably do is inject command frames, and filter these out.

On Fri, Jan 17, 2014 at 2:57 PM, Laurent Alebarde <l.alebarde at free.fr> wrote:
> For trimming an incoming message, the very beginning of in_event looks like
> the right place.
> For prepending an outgoing message, I would guess out_event just at the
> beginning of the if (!outsize) block. But I am not sure.
>
> What is the granularity of what is written with out_event / int nbytes =
> write (outpos, outsize); , frame ? message ? several message possible ? part
> of a frame possible ?
>
>
> Le 17/01/2014 11:40, Laurent Alebarde a écrit :
>
> Hi Devs,
>
> I am doing some experiments (cf at the end for the goal) and wonder where I
> could hook the beginning of a message both reading and writing.
>
> What I want to do is prepend an outgoing message and trim an incoming
> message (for any mechanism looks simpler) when some option is set.
>
> Typically, when the option is set, when a new message is received, I want to
> be able to store a certain amount of the first bytes in a new mechanism
> buffer, and skip them. These bytes are experimental and not ZMTP, so I have
> to skip or trim them to not hurt ZMTP. When a message is sent, I want to
> initialise the buffer with a copy of what I previously stored before ZMTP
> write the buffer. If it is outpos, I will do outpos += store_size;
>
> So, the question is where & when I should do that to not hurt ZMTP.
>
> FYI, The aim of this experiment is to manage to achieve CURVE proxying. My
> investigations and tests so far lead me to prepend the client ID in every
> message sent to the CURVE worker, and that the worker send back this
> information.
>
> Cheers,
>
>
> Laurent
>
>
> _______________________________________________
> zeromq-dev mailing list
> zeromq-dev at lists.zeromq.org
> http://lists.zeromq.org/mailman/listinfo/zeromq-dev
>
>
>
> _______________________________________________
> zeromq-dev mailing list
> zeromq-dev at lists.zeromq.org
> http://lists.zeromq.org/mailman/listinfo/zeromq-dev
>



More information about the zeromq-dev mailing list