zmq_send(3)

SYNOPSIS

int zmq_send (void *socket, zmq_msg_t *msg, int flags);

DESCRIPTION

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:

-ZMQ_NOBLOCK -: -
-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. -
-
-ZMQ_SNDMORE -: -
-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. -
-

- - - -

Note

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 ØMQ has assumed responsibility for the message.

Multi-part messages

A ØMQ message is composed of 1 or more message parts; each message part is an -independent zmq_msg_t in its own right. ØMQ 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 ØMQ -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.

RETURN VALUE

The zmq_send() function shall return zero if successful. Otherwise it shall -return -1 and set errno to one of the values defined below.

ERRORS

-EAGAIN -: -
-Non-blocking mode was requested and the message cannot be sent at the moment. -
-
-ENOTSUP -: -
-The zmq_send() operation is not supported by this socket type. -
-
-EFSM -: -
-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. -
-
-ETERM -: -
-The ØMQ context associated with the specified socket was terminated. -
-
-EFAULT -: -
-The provided context was not valid (NULL). -
-

EXAMPLE

Filling in a message and sending it to a socket

/* Create a new message, allocating 6 bytes for message content */
-zmq_msg_t msg;
-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);

AUTHORS

The ØMQ documentation was written by Martin Sustrik <sustrik@250bpm.com> and -Martin Lucina <mato@kotelna.sk>.

-zmq_send(3) Manual Page -

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