NAME

       zmq_send - send a message part on a socket

SYNOPSIS

       int zmq_send (void *socket, const void *buf, size_t len, int flags);

DESCRIPTION

       The zmq_send() function shall queue a message created from the buffer referenced by the
       buf and len arguments. The flags argument is a combination of the flags defined below:

       ZMQ_DONTWAIT
           For socket types (DEALER, PUSH) that block (either with ZMQ_IMMEDIATE option set and
           no peer available, or all peers having 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_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 0MQ has
           assumed responsibility for the message.

   Multi-part messages
       A 0MQ message is composed of 1 or more message parts. 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_send() 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_send() operation is not supported by this socket type.

       EINVAL
           The sender tried to send multipart data, which the socket type does not allow.

       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 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.

       EHOSTUNREACH
           The message cannot be routed.

EXAMPLE

       Sending a multi-part message.

           /* Send a multi-part message consisting of three parts to socket */
           rc = zmq_send (socket, "ABC", 3, ZMQ_SNDMORE);
           assert (rc == 3);
           rc = zmq_send (socket, "DEFGH", 5, ZMQ_SNDMORE);
           assert (rc == 5);
           /* Final part; no more parts to follow */
           rc = zmq_send (socket, "JK", 2, 0);
           assert (rc == 2);

SEE ALSO

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

AUTHORS

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       Contribution Policy at http://www.zeromq.org/docs:contributing.