NAME

       zmq_sendmsg - send a message part on a socket

SYNOPSIS

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

DESCRIPTION

       The zmq_sendmsg() 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_DONTWAIT
           For socket types (DEALER, PUSH) that block when there are no available peers (or all
           peers have full high-water mark), specifies that the operation should be performed in
           non-blocking mode. If the message cannot be queued on the socket, the zmq_sendmsg()
           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.

       The zmq_msg_t structure passed to zmq_sendmsg() 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()).

           Note
           A successful invocation of zmq_sendmsg() 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 message.

           Note
           this API method is deprecated in favor of zmq_msg_send(3).

   Multi-part messages
       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 except by available memory.

       An application that sends multi-part messages must use the ZMQ_SNDMORE flag when sending
       each message part except the final one.

RETURN VALUE

       The zmq_sendmsg() function shall return number of bytes in the message 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_sendmsg() operation is not supported by this socket type.

       EFSM
           The zmq_sendmsg() 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 0MQ context associated with the specified socket was terminated.

       ENOTSOCK
           The provided socket was invalid.

       EINTR
           The operation was interrupted by delivery of a signal before the message was sent.

       EFAULT
           Invalid message.

       EHOSTUNREACH
           The message cannot be routed.

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_sendmsg (socket, &msg, 0);
           assert (rc == 6);

       Sending a multi-part message.

           /* Send a multi-part message consisting of three parts to socket */
           rc = zmq_sendmsg (socket, &part1, ZMQ_SNDMORE);
           rc = zmq_sendmsg (socket, &part2, ZMQ_SNDMORE);
           /* Final part; no more parts to follow */
           rc = zmq_sendmsg (socket, &part3, 0);

SEE ALSO

       zmq_recv(3) zmq_socket(7) zmq(7)

AUTHORS

       This page was written by the 0MQ community. To make a change please read the 0MQ
       Contribution Policy at http://www.zeromq.org/docs:contributing.