mirror of
https://github.com/zeromq/libzmq.git
synced 2025-10-28 19:52:00 +01:00
104 lines
3.3 KiB
Plaintext
104 lines
3.3 KiB
Plaintext
zmq_send_const(3)
|
|
=================
|
|
|
|
|
|
NAME
|
|
----
|
|
zmq_send_const - send a constant-memory message part on a socket
|
|
|
|
|
|
SYNOPSIS
|
|
--------
|
|
*int zmq_send_const (void '*socket', void '*buf', size_t 'len', int 'flags');*
|
|
|
|
|
|
DESCRIPTION
|
|
-----------
|
|
The _zmq_send_const()_ function shall queue a message created from the buffer
|
|
referenced by the 'buf' and 'len' arguments. The message buffer is assumed
|
|
to be constant-memory and will therefore not be copied or deallocated
|
|
in any way. 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_const()_ 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_const()_ 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_const()_ 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_const()_ operation is not supported by this socket type.
|
|
*EFSM*::
|
|
The _zmq_send_const()_ 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 linkzmq: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_const (socket, "ABC", 3, ZMQ_SNDMORE);
|
|
assert (rc == 3);
|
|
rc = zmq_send_const (socket, "DEFGH", 5, ZMQ_SNDMORE);
|
|
assert (rc == 5);
|
|
/* Final part; no more parts to follow */
|
|
rc = zmq_send_const (socket, "JK", 2, 0);
|
|
assert (rc == 2);
|
|
----
|
|
|
|
SEE ALSO
|
|
--------
|
|
linkzmq:zmq_send[3]
|
|
linkzmq:zmq_recv[3]
|
|
linkzmq:zmq_socket[7]
|
|
linkzmq: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>.
|