'\" t
.\"     Title: xs_send
.\"    Author: [see the "AUTHORS" section]
.\" Generator: DocBook XSL Stylesheets v1.75.2 <http://docbook.sf.net/>
.\"      Date: 06/13/2012
.\"    Manual: Crossroads I/O Manual
.\"    Source: Crossroads I/O 1.2.0
.\"  Language: English
.\"
.TH "XS_SEND" "3" "06/13/2012" "Crossroads I/O 1\&.2\&.0" "Crossroads I/O Manual"
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.SH "NAME"
xs_send \- send a message part on a socket
.SH "SYNOPSIS"
.sp
\fBint xs_send (void \fR\fB\fI*socket\fR\fR\fB, void \fR\fB\fI*buf\fR\fR\fB, size_t \fR\fB\fIlen\fR\fR\fB, int \fR\fB\fIflags\fR\fR\fB);\fR
.SH "DESCRIPTION"
.sp
The \fIxs_send()\fR function shall queue a message created from the buffer referenced by the \fIbuf\fR and \fIlen\fR arguments\&. The \fIflags\fR argument is a combination of the flags defined below:
.PP
\fBXS_DONTWAIT\fR
.RS 4
Specifies that the operation should be performed in non\-blocking mode\&. If the message cannot be queued on the
\fIsocket\fR, the
\fIxs_send()\fR
function shall fail with
\fIerrno\fR
set to EAGAIN\&.
.RE
.PP
\fBXS_SNDMORE\fR
.RS 4
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\&.
.RE
.if n \{\
.sp
.\}
.RS 4
.it 1 an-trap
.nr an-no-space-flag 1
.nr an-break-flag 1
.br
.ps +1
\fBNote\fR
.ps -1
.br
.sp
A successful invocation of \fIxs_send()\fR does not indicate that the message has been transmitted to the network, only that it has been queued on the \fIsocket\fR and Crossroads have assumed responsibility for the message\&.
.sp .5v
.RE
.SS "Multi\-part messages"
.sp
A Crossroads message is composed of 1 or more message parts\&. Crossroads ensures atomic delivery of messages; peers shall receive either all \fImessage parts\fR of a message or none at all\&. The total number of message parts is unlimited except by available memory\&.
.sp
An application that sends multipart messages must use the \fIXS_SNDMORE\fR flag when sending each message part except the final one\&.
.SH "RETURN VALUE"
.sp
The \fIxs_send()\fR function shall return number of bytes in the message if successful\&. Otherwise it shall return \-1 and set \fIerrno\fR to one of the values defined below\&.
.SH "ERRORS"
.PP
\fBEAGAIN\fR
.RS 4
Non\-blocking mode was requested and the message cannot be sent at the moment\&.
.RE
.PP
\fBENOTSUP\fR
.RS 4
The
\fIxs_send()\fR
operation is not supported by this socket type\&.
.RE
.PP
\fBEFSM\fR
.RS 4
The
\fIxs_send()\fR
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
\fImessaging patterns\fR
section of
\fBxs_socket\fR(3)
for more information\&.
.RE
.PP
\fBETERM\fR
.RS 4
The
\fIcontext\fR
associated with the specified
\fIsocket\fR
was terminated\&.
.RE
.PP
\fBENOTSOCK\fR
.RS 4
The provided
\fIsocket\fR
was invalid\&.
.RE
.PP
\fBEINTR\fR
.RS 4
The operation was interrupted by delivery of a signal before the message was sent\&.
.RE
.SH "EXAMPLE"
.PP
\fBSending a multi-part message\fR. 
.sp
.if n \{\
.RS 4
.\}
.nf
/* 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);
.fi
.if n \{\
.RE
.\}
.sp
.SH "SEE ALSO"
.sp
Applications that wish to use zero\-copy messaging must use \fBxs_sendmsg\fR(3) instead of \fIxs_send()\fR\&.
.sp
\fBxs_recv\fR(3) \fBxs_socket\fR(7) \fBxs\fR(7)
.SH "AUTHORS"
.sp
This man page was written by Martin Sustrik <\m[blue]\fBsustrik@250bpm\&.com\fR\m[]\&\s-2\u[1]\d\s+2>, Martin Lucina <\m[blue]\fBmartin@lucina\&.net\fR\m[]\&\s-2\u[2]\d\s+2> and Pieter Hintjens <\m[blue]\fBph@imatix\&.com\fR\m[]\&\s-2\u[3]\d\s+2>\&.
.SH "NOTES"
.IP " 1." 4
sustrik@250bpm.com
.RS 4
\%mailto:sustrik@250bpm.com
.RE
.IP " 2." 4
martin@lucina.net
.RS 4
\%mailto:martin@lucina.net
.RE
.IP " 3." 4
ph@imatix.com
.RS 4
\%mailto:ph@imatix.com
.RE