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<h1 class="lined-header"><span>cowboy_middleware(3)</span></h1>
<h2 id="_name">Name</h2>
<p>cowboy_middleware - Middlewares</p>
<h2 id="_description">Description</h2>
<p>The module <code>cowboy_middleware</code> defines a callback interface for Cowboy middlewares.</p>
<p>Middlewares process the request sequentially in the order they are configured.</p>
<h2 id="_callbacks">Callbacks</h2>
<p>Middlewares implement the following interface:</p>
<div class="listingblock"><div class="content"><!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt><b><font color="#000000">execute</font></b>(<font color="#009900">Req</font>, <font color="#009900">Env</font>)
<font color="#990000">-></font> {<font color="#FF6600">ok</font>, <font color="#009900">Req</font>, <font color="#009900">Env</font>}
| {<font color="#FF6600">suspend</font>, <b><font color="#000000">module</font></b>(), <b><font color="#000080">atom</font></b>(), [<b><font color="#000000">any</font></b>()]}
| {<font color="#FF6600">stop</font>, <font color="#009900">Req</font>}
<font color="#009900">Req</font> <font color="#990000">::</font> <b><font color="#000000">cowboy_req:req</font></b>()
<font color="#009900">Env</font> <font color="#990000">::</font> <b><font color="#000000">cowboy_middleware:env</font></b>()</tt></pre>
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<p>The <code>execute/2</code> is the only callback that needs to be implemented. It must execute the middleware and return with instructions for Cowboy.</p>
<dl><dt>ok</dt>
<dd><p>Cowboy should continue processing the request using the returned Req object and environment.</p>
</dd>
<dt>suspend</dt>
<dd><p>Cowboy will hibernate the process. When resuming, Cowboy will apply the returned module, function and arguments.</p>
</dd>
<dt>stop</dt>
<dd><p>Cowboy will stop middleware execution. No other middleware will be executed. This effectively ends the processing of the request.</p>
</dd>
</dl>
<!-- @todo No need to return the Req when stopping. Fix in 3.0.-->
<h2 id="_types">Types</h2>
<h3 id="_env">env()</h3>
<div class="listingblock"><div class="content"><!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><tt><b><font color="#000000">env</font></b>() <font color="#990000">::</font> #{<b><font color="#000080">atom</font></b>() <font color="#990000">=></font> <b><font color="#000000">any</font></b>()}</tt></pre>
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<p>Middleware environment.</p>
<p>A new environment is created for every request. The initial environment contained the user configured environment values (like <code>dispatch</code> for example) plus the <code>listener</code> value which contains the name of the listener for this connection.</p>
<p>Middlewares may modify the environment as necessary.</p>
<h2 id="_changelog">Changelog</h2>
<ul><li><strong>2.0</strong>: The <code>env</code> type is now a map instead of a proplist.
</li>
<li><strong>1.0</strong>: Behavior introduced.
</li>
</ul>
<h2 id="_see_also">See also</h2>
<p><a href="..">cowboy(7)</a></p>
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