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---
version: tip
layout: manpage_v2
title: nng_ctx_open(3)
---
<h1>nng_ctx_open(3)</h1>
<div class="sect1">
<h2 id="_name">NAME</h2>
<div class="sectionbody">
<div class="paragraph">
<p>nng_ctx_open - create context</p>
</div>
</div>
</div>
<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-w"> </span><span class="tok-cpf"><nng/nng.h></span>
<span class="tok-kt">int</span><span class="tok-w"> </span><span class="tok-nf">nng_ctx_open</span><span class="tok-p">(</span><span class="tok-n">nng_ctx</span><span class="tok-w"> </span><span class="tok-o">*</span><span class="tok-n">ctxp</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-n">nng_socket</span><span class="tok-w"> </span><span class="tok-n">s</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_ctx_open()</code> function creates a separate context to be used with
the socket <em>s</em>,
and returns it at the location pointed by <em>ctxp</em>.</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
Not every protocol supports creation of separate contexts.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>Contexts allow the independent and concurrent use of stateful operations
using the same socket.
For example, two different contexts created on a <a href="nng_rep.7.html"><em>rep</em></a>
socket can each receive requests, and send replies to them, without any
regard to or interference with each other.</p>
</div>
<div class="paragraph">
<p>
TIP: Using contexts is an excellent way to write simpler concurrent
applications, while retaining the benefits of the protocol-specific
advanced processing, avoiding the need to bypass that with
<a href="nng.7.html#raw_mode">raw mode</a> sockets.</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
Use of contexts with <a href="nng.7.html#raw_mode">raw mode</a> sockets is
nonsensical, and not supported.
</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_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 does not support separate contexts, or the socket was opened in raw mode.</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_ctx_close.3.html">nng_ctx_close(3)</a>,
<a href="nng_ctx_getopt.3.html">nng_ctx_getopt(3)</a>,
<a href="nng_ctx_recv.3.html">nng_ctx_recv(3)</a>,
<a href="nng_ctx_send.3.html">nng_ctx_send(3)</a>,
<a href="nng_ctx_setopt.3.html">nng_ctx_setopt(3)</a>,
<a href="nng_strerror.3.html">nng_strerror(3)</a>,
<a href="nng_ctx.5.html">nng_ctx(5)</a>,
<a href="nng_socket.5.html">nng_socket(5)</a>,
<a href="nng_rep.7.html">nng_rep(7)</a>,
<a href="nng_req.7.html">nng_req(7)</a>,
<a href="nng.7.html">nng(7)</a></p>
</div>
</div>
</div>
|
