zmq_send(3)

SYNOPSIS

int zmq_send (void *socket, 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 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_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. 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 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. +
+
+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. +
+
+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);

AUTHORS

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

+zmq_send(3) Manual Page +

NAME