XS_SEND(3) Crossroads I/O Manual XS_SEND(3)NAMExs_send - send a message part on a socket
SYNOPSIS
int xs_send (void *socket, void *buf, size_t len, int flags);
DESCRIPTION
The xs_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:
XS_DONTWAIT
Specifies that the operation should be performed in non-blocking
mode. If the message cannot be queued on the socket, the xs_send()
function shall fail with errno set to EAGAIN.
XS_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 xs_send() does not indicate that the
message has been transmitted to the network, only that it has been
queued on the socket and Crossroads have assumed responsibility for
the message.
Multi-part messages
A Crossroads message is composed of 1 or more message parts. Crossroads
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 multipart messages must use the XS_SNDMORE
flag when sending each message part except the final one.
RETURN VALUE
The xs_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 xs_send() operation is not supported by this socket type.
EFSM
The xs_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 XS_REP. See the messaging patterns section of
xs_socket(3) for more information.
ETERM
The 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.
EXAMPLE
Sending a multi-part message.
/* Send a multi-part message consisting of three parts to socket */
rc = xs_send (socket, "ABC", 3, XS_SNDMORE);
assert (rc == 3);
rc = xs_send (socket, "DEFGH", 5, XS_SNDMORE);
assert (rc == 5);
/* Final part; no more parts to follow */
rc = xs_send (socket, "JK", 2, 0);
assert (rc == 2);
SEE ALSO
Applications that wish to use zero-copy messaging must use
xs_sendmsg(3) instead of xs_send().
xs_recv(3)xs_socket(7)xs(7)AUTHORS
This man page was written by Martin Sustrik <sustrik@250bpm.com[1]>,
Martin Lucina <martin@lucina.net[2]> and Pieter Hintjens
<ph@imatix.com[3]>.
NOTES
1. sustrik@250bpm.com
mailto:sustrik@250bpm.com
2. martin@lucina.net
mailto:martin@lucina.net
3. ph@imatix.com
mailto:ph@imatix.com
Crossroads I/O 1.2.0 02/17/2016 XS_SEND(3)