As Luca said, no need for DRAFT API here.
zmsg_routing_id() is just a wrapper. you don't need the call to zframe_new_empty() before the call to zmsg_pop. zmsg_pop returns the frame so zframe_t *identity = zmsg_pop(msgIn); as first call after receiving the message just does the trick. then pop your data from the message while remembering the identity_frame. responding you just send a multi-frame message back to that socket where the identity_frame is the first one, followed by your data. ________________________________ From: zeromq-dev <[email protected]> on behalf of Luca Boccassi <[email protected]> Sent: Thursday, December 14, 2017 6:28 AM To: ZeroMQ development list Subject: Re: [zeromq-dev] CZMQ How to capture identity frame? On Wed, 2017-12-13 at 20:24 +0000, Stephen Gray wrote: > Using CZMQ I'm trying to capture the routing identity frame of a > message received off a ROUTER socket. I see in the draft API that > methods exist for this for a SERVER socket; > > > > #ifdef CZMQ_BUILD_DRAFT_API > > // *** Draft method, for development use, may change without warning > *** > > // Return message routing ID, if the message came from a ZMQ_SERVER > socket. > > // Else returns zero. > > CZMQ_EXPORT uint32_t > > zmsg_routing_id (zmsg_t *self); > > > > // *** Draft method, for development use, may change without warning > *** > > // Set routing ID on message. This is used if/when the message is > sent to a > > // ZMQ_SERVER socket. > > CZMQ_EXPORT void > > zmsg_set_routing_id (zmsg_t *self, uint32_t routing_id); > > > I believe my installation of CZMQ built the draft API; but I cannot > work out how to access it in my code, is a pre-processor definition > required? Also do the these methods also work for ROUTER sockets? > > Really though, I'd rather stick with the stable version. Please could > someone enlighten me on how to get the identity frame using CZMQ? I > tried this: > > //Inbound from ROUTER so will be carrying an identity frame > zframe_t *identity = zframe_new_empty(); > identity = zmsg_pop(msgIn);//strip off id frame > > but it crashes at runtime. > > With thanks, > > Stephen You don't need any special API. From the zmq_socket manpage: "When receiving messages a ZMQ_ROUTER socket shall prepend a message part containing the routing id of the originating peer to the message before passing it to the application." -- Kind regards, Luca Boccassi
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