1ZMQ_SENDMSG(3)                    0MQ Manual                    ZMQ_SENDMSG(3)
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NAME

6       zmq_sendmsg - send a message part on a socket
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SYNOPSIS

9       int zmq_sendmsg (void *socket, zmq_msg_t *msg, int flags);
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DESCRIPTION

12       The zmq_sendmsg() function shall queue the message referenced by the
13       msg argument to be sent to the socket referenced by the socket
14       argument. The flags argument is a combination of the flags defined
15       below:
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17       ZMQ_DONTWAIT
18           For socket types (DEALER, PUSH) that block (either with
19           ZMQ_IMMEDIATE option set and no peer available, or all peers having
20           full high-water mark), specifies that the operation should be
21           performed in non-blocking mode. If the message cannot be queued on
22           the socket, the zmq_sendmsg() function shall fail with errno set to
23           EAGAIN.
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25       ZMQ_SNDMORE
26           Specifies that the message being sent is a multi-part message, and
27           that further message parts are to follow. Refer to the section
28           regarding multi-part messages below for a detailed description.
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30       The zmq_msg_t structure passed to zmq_sendmsg() is nullified during the
31       call. If you want to send the same message to multiple sockets you have
32       to copy it (e.g. using zmq_msg_copy()).
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34           Note
35           A successful invocation of zmq_sendmsg() does not indicate that the
36           message has been transmitted to the network, only that it has been
37           queued on the socket and 0MQ has assumed responsibility for the
38           message.
39
40           Note
41           this API method is deprecated in favor of zmq_msg_send(3).
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43   Multi-part messages
44       A 0MQ message is composed of 1 or more message parts. Each message part
45       is an independent zmq_msg_t in its own right. 0MQ ensures atomic
46       delivery of messages: peers shall receive either all message parts of a
47       message or none at all. The total number of message parts is unlimited
48       except by available memory.
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50       An application that sends multi-part messages must use the ZMQ_SNDMORE
51       flag when sending each message part except the final one.
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RETURN VALUE

54       The zmq_sendmsg() function shall return number of bytes in the message
55       if successful. Otherwise it shall return -1 and set errno to one of the
56       values defined below.
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ERRORS

59       EAGAIN
60           Non-blocking mode was requested and the message cannot be sent at
61           the moment.
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63       ENOTSUP
64           The zmq_sendmsg() operation is not supported by this socket type.
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66       EINVAL
67           The sender tried to send multipart data, which the socket type does
68           not allow.
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70       EFSM
71           The zmq_sendmsg() operation cannot be performed on this socket at
72           the moment due to the socket not being in the appropriate state.
73           This error may occur with socket types that switch between several
74           states, such as ZMQ_REP. See the messaging patterns section of
75           zmq_socket(3) for more information.
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77       ETERM
78           The 0MQ context associated with the specified socket was
79           terminated.
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81       ENOTSOCK
82           The provided socket was invalid.
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84       EINTR
85           The operation was interrupted by delivery of a signal before the
86           message was sent.
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88       EFAULT
89           Invalid message.
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91       EHOSTUNREACH
92           The message cannot be routed.
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EXAMPLE

95       Filling in a message and sending it to a socket.
96
97           /* Create a new message, allocating 6 bytes for message content */
98           zmq_msg_t msg;
99           int rc = zmq_msg_init_size (&msg, 6);
100           assert (rc == 0);
101           /* Fill in message content with 'AAAAAA' */
102           memset (zmq_msg_data (&msg), 'A', 6);
103           /* Send the message to the socket */
104           rc = zmq_sendmsg (socket, &msg, 0);
105           assert (rc == 6);
106
107       Sending a multi-part message.
108
109           /* Send a multi-part message consisting of three parts to socket */
110           rc = zmq_sendmsg (socket, &part1, ZMQ_SNDMORE);
111           rc = zmq_sendmsg (socket, &part2, ZMQ_SNDMORE);
112           /* Final part; no more parts to follow */
113           rc = zmq_sendmsg (socket, &part3, 0);
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SEE ALSO

117       zmq_recv(3) zmq_socket(7) zmq(7)
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AUTHORS

120       This page was written by the 0MQ community. To make a change please
121       read the 0MQ Contribution Policy at
122       http://www.zeromq.org/docs:contributing.
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1260MQ 4.3.4                         07/23/2022                    ZMQ_SENDMSG(3)
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