'\" t
.\"     Title: zmq_msg_routing_id
.\"    Author: [see the "AUTHORS" section]
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 10/23/2023
.\"    Manual: 0MQ Manual
.\"    Source: 0MQ 4.3.5
.\"  Language: English
.\"
.TH "ZMQ_MSG_ROUTING_ID" "3" "10/23/2023" "0MQ 4\&.3\&.5" "0MQ Manual"
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.SH "NAME"
zmq_msg_routing_id \- return routing ID for message, if any
.SH "SYNOPSIS"
.sp
\fBuint32_t zmq_msg_routing_id (zmq_msg_t \fR\fB\fI*message\fR\fR\fB);\fR
.SH "DESCRIPTION"
.sp
The \fIzmq_msg_routing_id()\fR function returns the routing ID for the message, if any\&. The routing ID is set on all messages received from a \fIZMQ_SERVER\fR socket\&. To send a message to a \fIZMQ_SERVER\fR socket you must set the routing ID of a connected \fIZMQ_CLIENT\fR peer\&. Routing IDs are transient\&.
.SH "RETURN VALUE"
.sp
The \fIzmq_msg_routing_id()\fR function shall return zero if there is no routing ID, otherwise it shall return an unsigned 32\-bit integer greater than zero\&.
.SH "EXAMPLE"
.PP
\fBReceiving a client message and routing ID\fR. 
.sp
.if n \{\
.RS 4
.\}
.nf
void *ctx = zmq_ctx_new ();
assert (ctx);

void *server = zmq_socket (ctx, ZMQ_SERVER);
assert (server);
int rc = zmq_bind (server, "tcp://127\&.0\&.0\&.1:8080");
assert (rc == 0);

zmq_msg_t message;
rc = zmq_msg_init (&message);
assert (rc == 0);

//  Receive a message from socket
rc = zmq_msg_recv (server, &message, 0);
assert (rc != \-1);
uint32_t routing_id = zmq_msg_routing_id (&message);
assert (routing_id);
.fi
.if n \{\
.RE
.\}
.sp
.SH "SEE ALSO"
.sp
\fBzmq_msg_set_routing_id\fR(3)
.SH "AUTHORS"
.sp
This page was written by the 0MQ community\&. To make a change please read the 0MQ Contribution Policy at \m[blue]\fBhttp://www\&.zeromq\&.org/docs:contributing\fR\m[]\&.