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| -rw-r--r-- | docs/en/cowboy/2.0/guide/handlers/index.html | 175 |
1 files changed, 89 insertions, 86 deletions
diff --git a/docs/en/cowboy/2.0/guide/handlers/index.html b/docs/en/cowboy/2.0/guide/handlers/index.html index dbb50c85..33cd53e2 100644 --- a/docs/en/cowboy/2.0/guide/handlers/index.html +++ b/docs/en/cowboy/2.0/guide/handlers/index.html @@ -7,7 +7,7 @@ <meta name="description" content=""> <meta name="author" content="Loïc Hoguin based on a design from (Soft10) Pol Cámara"> - <meta name="generator" content="Hugo 0.17" /> + <meta name="generator" content="Hugo 0.26" /> <title>Nine Nines: Handlers</title> @@ -67,97 +67,100 @@ <h1 class="lined-header"><span>Handlers</span></h1> -<div class="paragraph"><p>Handlers are Erlang modules that handle HTTP requests.</p></div>
-<div class="sect1">
-<h2 id="_plain_http_handlers">Plain HTTP handlers</h2>
-<div class="sectionbody">
-<div class="paragraph"><p>The most basic handler in Cowboy implements the mandatory
-<code>init/2</code> callback, manipulates the request, optionally
-sends a response and then returns.</p></div>
-<div class="paragraph"><p>This callback receives the <a href="../req">Req object</a> and the initial
-state defined in the <a 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>
+<div class="paragraph"><p>Handlers are Erlang modules that handle HTTP requests.</p></div> +<div class="sect1"> +<h2 id="_plain_http_handlers">Plain HTTP handlers</h2> +<div class="sectionbody"> +<div class="paragraph"><p>The most basic handler in Cowboy implements the mandatory +<code>init/2</code> callback, manipulates the request, optionally +sends a response and then returns.</p></div> +<div class="paragraph"><p>This callback receives the <a href="../req">Req object</a> and the initial +state defined in the <a 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"> |