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diff --git a/docs/en/cowboy/2.2/guide/handlers/index.html b/docs/en/cowboy/2.2/guide/handlers/index.html new file mode 100644 index 00000000..cdfbf6dd --- /dev/null +++ b/docs/en/cowboy/2.2/guide/handlers/index.html @@ -0,0 +1,250 @@ +<!DOCTYPE html> +<html lang="en"> + +<head> + <meta charset="utf-8"> + <meta name="viewport" content="width=device-width, initial-scale=1.0"> + <meta name="description" content=""> + <meta name="author" content="Loïc Hoguin based on a design from (Soft10) Pol Cámara"> + + <meta name="generator" content="Hugo 0.30.2" /> + + <title>Nine Nines: Handlers</title> + + <link href='https://fonts.googleapis.com/css?family=Open+Sans:400,700,400italic' rel='stylesheet' type='text/css'> + <link href="/css/99s.css?r=1" rel="stylesheet"> + + <link rel="shortcut icon" href="/img/ico/favicon.ico"> + <link rel="apple-touch-icon-precomposed" sizes="114x114" href="/img/ico/apple-touch-icon-114.png"> + <link rel="apple-touch-icon-precomposed" sizes="72x72" 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href="../routing">router configuration</a>.</p></div> +<div class="paragraph"><p>A handler that does nothing would look like this:</p></div> +<div class="listingblock"> +<div class="content"><!-- Generator: GNU source-highlight 3.1.8 +by Lorenzo Bettini +http://www.lorenzobettini.it +http://www.gnu.org/software/src-highlite --> +<pre><tt><span style="font-weight: bold"><span style="color: #000000">init</span></span>(<span style="color: #009900">Req</span>, <span style="color: #009900">State</span>) <span style="color: #990000">-></span> + {<span style="color: #FF6600">ok</span>, <span style="color: #009900">Req</span>, <span style="color: #009900">State</span>}<span style="color: #990000">.</span></tt></pre></div></div> +<div class="paragraph"><p>Despite sending no reply, a <code>204 No Content</code> response will be +sent to the client, as Cowboy makes sure that a response is +sent for every request.</p></div> +<div class="paragraph"><p>We need to use the Req object to reply.</p></div> +<div class="listingblock"> +<div class="content"><!-- Generator: GNU source-highlight 3.1.8 +by Lorenzo Bettini +http://www.lorenzobettini.it +http://www.gnu.org/software/src-highlite --> +<pre><tt><span style="font-weight: bold"><span style="color: #000000">init</span></span>(<span style="color: #009900">Req0</span>, <span style="color: #009900">State</span>) <span style="color: #990000">-></span> + <span style="color: #009900">Req</span> <span style="color: #990000">=</span> <span style="font-weight: bold"><span style="color: #000000">cowboy_req:reply</span></span>(<span style="color: #993399">200</span>, #{ + <span style="color: #990000"><<</span><span style="color: #FF0000">"content-type"</span><span style="color: #990000">>></span> <span style="color: #990000">=></span> <span style="color: #990000"><<</span><span style="color: #FF0000">"text/plain"</span><span style="color: #990000">>></span> + }, <span style="color: #990000"><<</span><span style="color: #FF0000">"Hello World!"</span><span style="color: #990000">>></span>, <span style="color: #009900">Req0</span>), + {<span style="color: #FF6600">ok</span>, <span style="color: #009900">Req</span>, <span style="color: #009900">State</span>}<span style="color: #990000">.</span></tt></pre></div></div> +<div class="paragraph"><p>Cowboy will immediately send a response when <code>cowboy:reply/4</code> +is called.</p></div> +<div class="paragraph"><p>We then return a 3-tuple. <code>ok</code> means that the handler ran +successfully. We also give the modified Req back to Cowboy.</p></div> +<div class="paragraph"><p>The last value of the tuple is a state that will be used +in every subsequent callbacks to this handler. Plain HTTP +handlers only have one additional callback, the optional +and rarely used <code>terminate/3</code>.</p></div> +</div> +</div> +<div class="sect1"> +<h2 id="_other_handlers">Other handlers</h2> +<div class="sectionbody"> +<div class="paragraph"><p>The <code>init/2</code> callback can also be used to inform Cowboy +that this is a different kind of handler and that Cowboy +should switch to it. To do this you simply need to return +the module name of the handler type you want to switch to.</p></div> +<div class="paragraph"><p>Cowboy comes with three handler types you can switch to: +<a href="../rest_handlers">cowboy_rest</a>, <a href="#ws_handlers">cowboy_websocket</a> +and <a href="../loop_handlers">cowboy_loop</a>. In addition to those you +can define your own handler types.</p></div> +<div class="paragraph"><p>Switching is simple. Instead of returning <code>ok</code>, you simply +return the name of the handler type you want to use. The +following snippet switches to a Websocket handler:</p></div> +<div class="listingblock"> +<div class="content"><!-- Generator: GNU source-highlight 3.1.8 +by Lorenzo Bettini +http://www.lorenzobettini.it +http://www.gnu.org/software/src-highlite --> +<pre><tt><span style="font-weight: bold"><span style="color: #000000">init</span></span>(<span style="color: #009900">Req</span>, <span style="color: #009900">State</span>) <span style="color: #990000">-></span> + {<span style="color: #FF6600">cowboy_websocket</span>, <span style="color: #009900">Req</span>, <span style="color: #009900">State</span>}<span style="color: #990000">.</span></tt></pre></div></div> +</div> +</div> +<div class="sect1"> +<h2 id="_cleaning_up">Cleaning up</h2> +<div class="sectionbody"> +<div class="paragraph"><p>All handler types provide the optional <code>terminate/3</code> callback.</p></div> +<div class="listingblock"> +<div class="content"><!-- Generator: GNU source-highlight 3.1.8 +by Lorenzo Bettini +http://www.lorenzobettini.it +http://www.gnu.org/software/src-highlite --> +<pre><tt><span style="font-weight: bold"><span style="color: #000000">terminate</span></span>(<span style="color: #009900">_Reason</span>, <span style="color: #009900">_Req</span>, <span style="color: #009900">_State</span>) <span style="color: #990000">-></span> + <span style="color: #FF6600">ok</span><span style="color: #990000">.</span></tt></pre></div></div> +<div class="paragraph"><p>This callback is strictly reserved for any required cleanup. +You cannot send a response from this function. There is no +other return value.</p></div> +<div class="paragraph"><p>This callback is optional because it is rarely necessary. +Cleanup should be done in separate processes directly (by +monitoring the handler process to detect when it exits).</p></div> +<div class="paragraph"><p>Cowboy does not reuse processes for different requests. The +process will terminate soon after this call returns.</p></div> +</div> +</div> + + + + + + + + + + + <nav style="margin:1em 0"> + + <a style="float:left" href="https://ninenines.eu/docs/en/cowboy/2.2/guide/constraints/"> + Constraints + </a> + + + + <a style="float:right" href="https://ninenines.eu/docs/en/cowboy/2.2/guide/loop_handlers/"> + Loop handlers + </a> + + </nav> + + + + +</div> + +<div class="span3 sidecol"> + + +<h3> + Cowboy + 2.2 + + User Guide +</h3> + +<ul> + + <li><a href="/docs/en/cowboy/2.2/guide">User Guide</a></li> + + + <li><a href="/docs/en/cowboy/2.2/manual">Function Reference</a></li> + + +</ul> + +<h4 id="docs-nav">Navigation</h4> + +<h4>Version select</h4> +<ul> + + + + <li><a href="/docs/en/cowboy/2.2/guide">2.2</a></li> + + <li><a href="/docs/en/cowboy/2.1/guide">2.1</a></li> + + <li><a href="/docs/en/cowboy/2.0/guide">2.0</a></li> + + <li><a href="/docs/en/cowboy/1.0/guide">1.0</a></li> + +</ul> + +</div> +</div> +</div> +</div> + + <footer> + <div class="container"> + <div class="row"> + <div class="span6"> + <p id="scroll-top"><a href="#">↑ Scroll to top</a></p> + <nav> + <ul> + <li><a href="mailto:[email protected]" title="Contact us">Contact us</a></li><li><a href="https://github.com/ninenines/ninenines.github.io" title="Github repository">Contribute to this site</a></li> + </ul> + </nav> + </div> + <div class="span6 credits"> + <p><img src="/img/footer_logo.png"></p> + <p>Copyright © Loïc Hoguin 2012-2016</p> + </div> + </div> + </div> + </footer> + + + <script src="/js/custom.js"></script> + </body> +</html> + + |