ZMQ_SEND(3) 0MQ Manual ZMQ_SEND(3)
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
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.
0MQ 4.3.4 01/18/2023 ZMQ_SEND(3)
Generated by dwww version 1.15 on Wed Jun 26 18:08:57 CEST 2024.