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 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

AUTHORS

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