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---
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---
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<h1>nng_sendmsg(3) Manual Page</h1>
<div id="toc" class="toc2">
<div id="toctitle">Table of Contents</div>
<ul class="sectlevel1">
<li><a href="#_synopsis">SYNOPSIS</a></li>
<li><a href="#_description">DESCRIPTION</a></li>
<li><a href="#_return_values">RETURN VALUES</a></li>
<li><a href="#_errors">ERRORS</a></li>
<li><a href="#_see_also">SEE ALSO</a></li>
</ul>
</div>
<h2 id="_name">NAME</h2>
<div class="sectionbody">
<p>nng_sendmsg - send message</p>
</div>
</div>
<div id="content">
<div class="sect1">
<h2 id="_synopsis">SYNOPSIS</h2>
<div class="sectionbody">
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="c"><span></span><span class="tok-cp">#include</span> <span class="tok-cpf"><nng/nng.h></span><span class="tok-cp"></span>
<span class="tok-kt">int</span> <span class="tok-nf">nng_sendmsg</span><span class="tok-p">(</span><span class="tok-n">nng_socket</span> <span class="tok-n">s</span><span class="tok-p">,</span> <span class="tok-n">nng_msg</span> <span class="tok-o">*</span><span class="tok-n">msg</span><span class="tok-p">,</span> <span class="tok-kt">int</span> <span class="tok-n">flags</span><span class="tok-p">);</span></code></pre>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_description">DESCRIPTION</h2>
<div class="sectionbody">
<div class="paragraph">
<p>The <code>nng_sendmsg()</code> sends message <em>msg</em> using the socket <em>s</em>.</p>
</div>
<div class="paragraph">
<p>If the function returns zero, indicating it has accepted the message for
delivery, then the <em>msg</em> is “owned” by the socket <em>s</em>, and the caller
must not make any further use of it.
The socket will free the message when it is finished.</p>
</div>
<div class="paragraph">
<p>If the function returns non-zero, then it is the caller’s responsibility
to dispose of the <em>msg</em>, which may include freeing it, sending it to
another socket, or simply trying again later.</p>
</div>
<div class="admonitionblock tip">
<table>
<tr>
<td class="icon">
<i class="fa icon-tip" title="Tip"></i>
</td>
<td class="content">
Using this function gives access to the message structure, and may
offer more functionality than the simpler <a href="nng_send.3.html"><code>nng_send()</code></a> function.
</td>
</tr>
</table>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
The semantics of what sending a message means vary from protocol to
protocol, so examination of the protocol documentation is encouraged.
(For example, with a <a href="nng_pub.7.html"><em>pub</em></a> socket the data is broadcast, so that
any peers who have a suitable subscription will be able to receive it using
<a href="nng_recv.3.html"><code>nng_recv()</code></a> or a similar function.)
Furthermore, some protocols may not support sending (such as
<a href="nng_sub.7.html"><em>sub</em></a>) or may require other conditions.
(For example, <a href="nng_rep.7.html"><em>rep</em></a> sockets cannot normally send data, which
are responses to requests, until they have first received a request.)
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>The <em>flags</em> may contain the following value:</p>
</div>
<div class="dlist">
<dl>
<dt class="hdlist1"><code>NNG_FLAG_NONBLOCK</code></dt>
<dd>
<p>The function returns immediately, regardless of whether
the socket is able to accept the data or not.
If the socket is unable to accept the data (such as if backpressure exists
because the peers are consuming messages too slowly, or no peer is present),
then the function will return with <code>NNG_EAGAIN</code>.
If this flag is not specified, then the function will block if such a
condition exists.</p>
</dd>
</dl>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
Regardless of the presence or absence of <code>NNG_FLAG_NONBLOCK</code>, there may
be queues between the sender and the receiver.
Furthermore, there is no guarantee that the message has actually been delivered.
Finally, with some protocols, the semantic is implicitly <code>NNG_FLAG_NONBLOCK</code>,
such as with <a href="nng_pub.7.html"><em>pub</em></a> sockets, which are best-effort delivery only.
</td>
</tr>
</table>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_return_values">RETURN VALUES</h2>
<div class="sectionbody">
<div class="paragraph">
<p>This function returns 0 on success, and non-zero otherwise.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_errors">ERRORS</h2>
<div class="sectionbody">
<div class="hdlist">
<table>
<tr>
<td class="hdlist1">
<code>NNG_EAGAIN</code>
</td>
<td class="hdlist2">
<p>The operation would block, but <code>NNG_FLAG_NONBLOCK</code> was specified.</p>
</td>
</tr>
<tr>
<td class="hdlist1">
<code>NNG_ECLOSED</code>
</td>
<td class="hdlist2">
<p>The socket <em>s</em> is not open.</p>
</td>
</tr>
<tr>
<td class="hdlist1">
<code>NNG_EINVAL</code>
</td>
<td class="hdlist2">
<p>An invalid set of <em>flags</em> was specified.</p>
</td>
</tr>
<tr>
<td class="hdlist1">
<code>NNG_EMSGSIZE</code>
</td>
<td class="hdlist2">
<p>The value of <em>size</em> is too large.</p>
</td>
</tr>
<tr>
<td class="hdlist1">
<code>NNG_ENOMEM</code>
</td>
<td class="hdlist2">
<p>Insufficient memory is available.</p>
</td>
</tr>
<tr>
<td class="hdlist1">
<code>NNG_ENOTSUP</code>
</td>
<td class="hdlist2">
<p>The protocol for socket <em>s</em> does not support sending.</p>
</td>
</tr>
<tr>
<td class="hdlist1">
<code>NNG_ESTATE</code>
</td>
<td class="hdlist2">
<p>The socket <em>s</em> cannot send data in this state.</p>
</td>
</tr>
<tr>
<td class="hdlist1">
<code>NNG_ETIMEDOUT</code>
</td>
<td class="hdlist2">
<p>The operation timed out.</p>
</td>
</tr>
</table>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_see_also">SEE ALSO</h2>
<div class="sectionbody">
<div class="paragraph text-left">
<p><a href="nng_msg_alloc.3.html">nng_msg_alloc(3)</a>,
<a href="nng_recvmsg.3.html">nng_recvmsg(3)</a>,
<a href="nng_send.3.html">nng_send(3)</a>,
<a href="nng_strerror.3.html">nng_strerror(3)</a>,
<a href="nng_msg.5.html">nng_msg(5)</a>,
<a href="nng_socket.5.html">nng_socket(5)</a>,
<a href="nng.7.html">nng(7)</a></p>
</div>
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