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.
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.
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.
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.
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);
