doc/zmq_send.html

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<body>
<div id="header">
<h1>
zmq_send(3) Manual Page
</h1>
<h2>NAME</h2>
<div class="sectionbody">
<p>zmq_send -
   send a message on a socket
</p>
</div>
</div>
<div id="content">
<h2 id="_synopsis">SYNOPSIS</h2>
<div class="sectionbody">
<div class="paragraph"><p><strong>int zmq_send (void <em>*socket</em>, zmq_msg_t <em>*msg</em>, int <em>flags</em>);</strong></p></div>
</div>
<h2 id="_description">DESCRIPTION</h2>
<div class="sectionbody">
<div class="paragraph"><p>The <em>zmq_send()</em> function shall queue the message referenced by the <em>msg</em>
argument to be sent to the socket referenced by the <em>socket</em> argument.  The
<em>flags</em> argument is a combination of the flags defined below:</p></div>
<div class="dlist"><dl>
<dt class="hdlist1">
<strong>ZMQ_NOBLOCK</strong>
</dt>
<dd>
<p>
Specifies that the operation should be performed in non-blocking mode. If the
message cannot be queued on the <em>socket</em>, the <em>zmq_send()</em> function shall fail
with <em>errno</em> set to EAGAIN.
</p>
</dd>
<dt class="hdlist1">
<strong>ZMQ_SNDMORE</strong>
</dt>
<dd>
<p>
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.
</p>
</dd>
</dl></div>
<div class="paragraph"><p>The <em>zmq_msg_t</em> structure passed to <em>zmq_send()</em> is nullified during the call.
If you want to send the same message to multiple sockets you have to copy it
using (e.g. using <em>zmq_msg_copy()</em>).</p></div>
<div class="admonitionblock">
<table><tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">A successful invocation of <em>zmq_send()</em> does not indicate that the
message has been transmitted to the network, only that it has been queued on
the <em>socket</em> and ØMQ has assumed responsibility for the message.</td>
</tr></table>
</div>
<h3 id="_multi_part_messages">Multi-part messages</h3><div style="clear:left"></div>
<div class="paragraph"><p>A ØMQ message is composed of 1 or more message parts; each message part is an
independent <em>zmq_msg_t</em> in its own right. ØMQ ensures atomic delivery of
messages; peers shall receive either all <em>message parts</em> of a message or none
at all.</p></div>
<div class="paragraph"><p>The total number of message parts is unlimited.</p></div>
<div class="paragraph"><p>An application wishing to send a multi-part message does so by specifying the
<em>ZMQ_SNDMORE</em> flag to <em>zmq_send()</em>. The presence of this flag indicates to ØMQ
that the message being sent is a multi-part message and that more message parts
are to follow. When the application wishes to send the final message part it
does so by calling <em>zmq_send()</em> without the <em>ZMQ_SNDMORE</em> flag; this indicates
that no more message parts are to follow.</p></div>
</div>
<h2 id="_return_value">RETURN VALUE</h2>
<div class="sectionbody">
<div class="paragraph"><p>The <em>zmq_send()</em> function shall return zero if successful. Otherwise it shall
return <tt>-1</tt> and set <em>errno</em> to one of the values defined below.</p></div>
</div>
<h2 id="_errors">ERRORS</h2>
<div class="sectionbody">
<div class="dlist"><dl>
<dt class="hdlist1">
<strong>EAGAIN</strong>
</dt>
<dd>
<p>
Non-blocking mode was requested and the message cannot be sent at the moment.
</p>
</dd>
<dt class="hdlist1">
<strong>ENOTSUP</strong>
</dt>
<dd>
<p>
The <em>zmq_send()</em> operation is not supported by this socket type.
</p>
</dd>
<dt class="hdlist1">
<strong>EFSM</strong>
</dt>
<dd>
<p>
The <em>zmq_send()</em> 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
<em>messaging patterns</em> section of <a href="zmq_socket.html">zmq_socket(3)</a> for more information.
</p>
</dd>
<dt class="hdlist1">
<strong>ETERM</strong>
</dt>
<dd>
<p>
The ØMQ <em>context</em> associated with the specified <em>socket</em> was terminated.
</p>
</dd>
<dt class="hdlist1">
<strong>ENOTSOCK</strong>
</dt>
<dd>
<p>
The provided <em>socket</em> was invalid.
</p>
</dd>
<dt class="hdlist1">
<strong>EINTR</strong>
</dt>
<dd>
<p>
The operation was interrupted by delivery of a signal before the message was
sent.
</p>
</dd>
<dt class="hdlist1">
<strong>EFAULT</strong>
</dt>
<dd>
<p>
Invalid message.
</p>
</dd>
</dl></div>
</div>
<h2 id="_example">EXAMPLE</h2>
<div class="sectionbody">
<div class="listingblock">
<div class="title">Filling in a message and sending it to a socket</div>
<div class="content">
<pre><tt>/* Create a new message, allocating 6 bytes for message content */
zmq_msg_t msg;
int rc = zmq_msg_init_size (&amp;msg, 6);
assert (rc == 0);
/* Fill in message content with 'AAAAAA' */
memset (zmq_msg_data (&amp;msg), 'A', 6);
/* Send the message to the socket */
rc = zmq_send (socket, &amp;msg, 0);
assert (rc == 0);</tt></pre>
</div></div>
<div class="listingblock">
<div class="title">Sending a multi-part message</div>
<div class="content">
<pre><tt>/* Send a multi-part message consisting of three parts to socket */
rc = zmq_send (socket, &amp;part1, ZMQ_SNDMORE);
rc = zmq_send (socket, &amp;part2, ZMQ_SNDMORE);
/* Final part; no more parts to follow */
rc = zmq_send (socket, &amp;part3, 0);</tt></pre>
</div></div>
</div>
<h2 id="_see_also">SEE ALSO</h2>
<div class="sectionbody">
<div class="paragraph"><p><a href="zmq_recv.html">zmq_recv(3)</a>
<a href="zmq_socket.html">zmq_socket(7)</a>
<a href="zmq.html">zmq(7)</a></p></div>
</div>
<h2 id="_authors">AUTHORS</h2>
<div class="sectionbody">
<div class="paragraph"><p>This ØMQ manual page was written by Martin Sustrik &lt;<a href="mailto:sustrik@250bpm.com">sustrik@250bpm.com</a>&gt; and
Martin Lucina &lt;<a href="mailto:mato@kotelna.sk">mato@kotelna.sk</a>&gt;.</p></div>
</div>
</div>
<div id="footnotes"><hr /></div>
<div id="footer">
<div id="footer-text">
ØMQ 2.1.6<br />
Last updated 2011-05-07 07:13:32 CEST
</div>
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