Provided by: libzmq-dev_2.1.11-1ubuntu1_i386
zmq_send - send a message on a socket
int zmq_send (void *socket, zmq_msg_t *msg, int flags);
The zmq_send() function shall queue the message referenced by the msg
argument to be sent to the socket referenced by the socket argument.
The flags argument is a combination of the flags defined below:
Specifies that the operation should be performed in non-blocking
mode. If the message cannot be queued on the socket, the zmq_send()
function shall fail with errno set to EAGAIN.
Specifies that the message being sent is a multi-part message, and
that further message parts are to follow. Refer to the section
regarding multi-part messages below for a detailed description.
The zmq_msg_t structure passed to zmq_send() is nullified during the
call. If you want to send the same message to multiple sockets you have
to copy it using (e.g. using zmq_msg_copy()).
A successful invocation of zmq_send() does not indicate that the
message has been transmitted to the network, only that it has been
queued on the socket and 0MQ has assumed responsibility for the
A 0MQ message is composed of 1 or more message parts; each message part
is an independent zmq_msg_t in its own right. 0MQ ensures atomic
delivery of messages; peers shall receive either all message parts of a
message or none at all.
The total number of message parts is unlimited.
An application wishing to send a multi-part message does so by
specifying the ZMQ_SNDMORE flag to zmq_send(). The presence of this
flag indicates to 0MQ that the message being sent is a multi-part
message and that more message parts are to follow. When the application
wishes to send the final message part it does so by calling zmq_send()
without the ZMQ_SNDMORE flag; this indicates that no more message parts
are to follow.
The zmq_send() function shall return zero if successful. Otherwise it
shall return -1 and set errno to one of the values defined below.
Non-blocking mode was requested and the message cannot be sent at
The zmq_send() operation is not supported by this socket type.
The zmq_send() operation cannot be performed on this socket at the
moment due to the socket not being in the appropriate state. This
error may occur with socket types that switch between several
states, such as ZMQ_REP. See the messaging patterns section of
zmq_socket(3) for more information.
The 0MQ context associated with the specified socket was
The provided socket was invalid.
The operation was interrupted by delivery of a signal before the
message was sent.
Filling in a message and sending it to a socket.
/* Create a new message, allocating 6 bytes for message content */
int rc = zmq_msg_init_size (&msg, 6);
assert (rc == 0);
/* Fill in message content with 'AAAAAA' */
memset (zmq_msg_data (&msg), 'A', 6);
/* Send the message to the socket */
rc = zmq_send (socket, &msg, 0);
assert (rc == 0);
Sending a multi-part message.
/* Send a multi-part message consisting of three parts to socket */
rc = zmq_send (socket, &part1, ZMQ_SNDMORE);
rc = zmq_send (socket, &part2, ZMQ_SNDMORE);
/* Final part; no more parts to follow */
rc = zmq_send (socket, &part3, 0);
zmq_recv(3) zmq_socket(7) zmq(7)
This 0MQ manual page was written by Martin Sustrik
<firstname.lastname@example.org> and Martin Lucina <email@example.com>.