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| author | Loïc Hoguin <[email protected]> | 2017-12-11 11:27:17 +0100 |
|---|---|---|
| committer | Loïc Hoguin <[email protected]> | 2017-12-11 11:27:17 +0100 |
| commit | 1b863c350ba1f9b8ad1cb458df514ab0fe6bb127 (patch) | |
| tree | f3f88acba06cce7095a047da8163ac0f92b1a64a /docs/en/cowboy/2.2/guide/resp/index.html | |
| parent | 35825f89b61579d4270d6970609047945277acf7 (diff) | |
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Add documentation for Cowboy 2.2
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diff --git a/docs/en/cowboy/2.2/guide/resp/index.html b/docs/en/cowboy/2.2/guide/resp/index.html new file mode 100644 index 00000000..0b18cc4c --- /dev/null +++ b/docs/en/cowboy/2.2/guide/resp/index.html @@ -0,0 +1,505 @@ +<!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: Sending a response</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" href="/img/ico/apple-touch-icon-72.png"> + <link rel="apple-touch-icon-precomposed" href="/img/ico/apple-touch-icon-57.png"> + + +</head> + + +<body class=""> + <header id="page-head"> + <div id="topbar" class="container"> + <div class="row"> + <div class="span2"> + <h1 id="logo"><a href="/" title="99s">99s</a></h1> + </div> + <div class="span10"> + + <div id="side-header"> + <nav> + <ul> + <li><a title="Hear my thoughts" href="/articles">Articles</a></li> + <li><a title="Watch my talks" href="/talks">Talks</a></li> + <li class="active"><a title="Read the docs" href="/docs">Documentation</a></li> + <li><a title="Request my services" href="/services">Consulting & Training</a></li> + </ul> + </nav> + <ul id="social"> + <li> + <a href="https://github.com/ninenines" title="Check my Github repositories"><img src="/img/ico_github.png" data-hover="/img/ico_github_alt.png" alt="Github"></a> + </li> + <li> + <a title="Keep in touch!" href="http://twitter.com/lhoguin"><img src="/img/ico_microblog.png" data-hover="/img/ico_microblog_alt.png"></a> + </li> + <li> + <a title="Contact me" href="mailto:[email protected]"><img src="/img/ico_mail.png" data-hover="/img/ico_mail_alt.png"></a> + </li> + </ul> + </div> + </div> + </div> + </div> + + +</header> + +<div id="contents" class="two_col"> +<div class="container"> +<div class="row"> +<div id="docs" class="span9 maincol"> + +<h1 class="lined-header"><span>Sending a response</span></h1> + +<div class="paragraph"><p>The response must be sent using the Req object.</p></div> +<div class="paragraph"><p>Cowboy provides two different ways of sending responses: +either directly or by streaming the body. Response headers +and body may be set in advance. The response is sent as +soon as one of the reply or stream reply function is +called.</p></div> +<div class="paragraph"><p>Cowboy also provides a simplified interface for sending +files. It can also send only specific parts of a file.</p></div> +<div class="paragraph"><p>While only one response is allowed for every request, +HTTP/2 introduced a mechanism that allows the server +to push additional resources related to the response. +This chapter also describes how this feature works in +Cowboy.</p></div> +<div class="sect1"> +<h2 id="_reply">Reply</h2> +<div class="sectionbody"> +<div class="paragraph"><p>Cowboy provides three functions for sending the entire reply, +depending on whether you need to set headers and body. In all +cases, Cowboy will add any headers required by the protocol +(for example the date header will always be sent).</p></div> +<div class="paragraph"><p>When you need to set only the status code, +use <code>cowboy_req:reply/2</code>:</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="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: #009900">Req0</span>)<span style="color: #990000">.</span></tt></pre></div></div> +<div class="paragraph"><p>When you need to set response headers at the same time, +use <code>cowboy_req:reply/3</code>:</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="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">303</span>, #{ + <span style="color: #990000"><<</span><span style="color: #FF0000">"location"</span><span style="color: #990000">>></span> <span style="color: #990000">=></span> <span style="color: #990000"><<</span><span style="color: #FF0000">"https://ninenines.eu"</span><span style="color: #990000">>></span> +}, <span style="color: #009900">Req0</span>)<span style="color: #990000">.</span></tt></pre></div></div> +<div class="paragraph"><p>Note that the header name must always be a lowercase +binary.</p></div> +<div class="paragraph"><p>When you also need to set the response body, +use <code>cowboy_req:reply/4</code>:</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="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: #FF0000">"Hello world!"</span>, <span style="color: #009900">Req0</span>)<span style="color: #990000">.</span></tt></pre></div></div> +<div class="paragraph"><p>You should always set the content-type header when the +response has a body. There is however no need to set +the content-length header; Cowboy does it automatically.</p></div> +<div class="paragraph"><p>The response body and the header values must be either +a binary or an iolist. An iolist is a list containing +binaries, characters, strings or other iolists. This +allows you to build a response from different parts +without having to do any concatenation:</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="color: #009900">Title</span> <span style="color: #990000">=</span> <span style="color: #FF0000">"Hello world!"</span>, +<span style="color: #009900">Body</span> <span style="color: #990000">=</span> <span style="color: #990000"><<</span><span style="color: #FF0000">"Hats off!"</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/html"</span><span style="color: #990000">>></span> +}, [<span style="color: #FF0000">"<html><head><title>"</span>, <span style="color: #009900">Title</span>, <span style="color: #FF0000">"</title></head>"</span>, + <span style="color: #FF0000">"<body><p>"</span>, <span style="color: #009900">Body</span>, <span style="color: #FF0000">"</p></body></html>"</span>], <span style="color: #009900">Req0</span>)<span style="color: #990000">.</span></tt></pre></div></div> +<div class="paragraph"><p>This method of building responses is more efficient than +concatenating. Behind the scenes, each element of the list +is simply a pointer, and those pointers are used directly +when writing to the socket.</p></div> +</div> +</div> +<div class="sect1"> +<h2 id="_stream_reply">Stream reply</h2> +<div class="sectionbody"> +<div class="paragraph"><p>Cowboy provides two functions for initiating a response, +and an additional function for streaming the response body. +Cowboy will add any required headers to the response.</p></div> +<div class="paragraph"><p>When you need to set only the status code, +use <code>cowboy_req:stream_reply/2</code>:</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="color: #009900">Req</span> <span style="color: #990000">=</span> <span style="font-weight: bold"><span style="color: #000000">cowboy_req:stream_reply</span></span>(<span style="color: #993399">200</span>, <span style="color: #009900">Req0</span>), + +<span style="font-weight: bold"><span style="color: #000000">cowboy_req:stream_body</span></span>(<span style="color: #FF0000">"Hello..."</span>, <span style="color: #FF6600">nofin</span>, <span style="color: #009900">Req</span>), +<span style="font-weight: bold"><span style="color: #000000">cowboy_req:stream_body</span></span>(<span style="color: #FF0000">"chunked..."</span>, <span style="color: #FF6600">nofin</span>, <span style="color: #009900">Req</span>), +<span style="font-weight: bold"><span style="color: #000000">cowboy_req:stream_body</span></span>(<span style="color: #FF0000">"world!!"</span>, <span style="color: #FF6600">fin</span>, <span style="color: #009900">Req</span>)<span style="color: #990000">.</span></tt></pre></div></div> +<div class="paragraph"><p>The second argument to <code>cowboy_req:stream_body/3</code> indicates +whether this data terminates the body. Use <code>fin</code> for the +final flag, and <code>nofin</code> otherwise.</p></div> +<div class="paragraph"><p>This snippet does not set a content-type header. This is +not recommended. All responses with a body should have +a content-type. The header can be set beforehand, or +using the <code>cowboy_req:stream_reply/3</code>:</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="color: #009900">Req</span> <span style="color: #990000">=</span> <span style="font-weight: bold"><span style="color: #000000">cowboy_req:stream_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/html"</span><span style="color: #990000">>></span> +}, <span style="color: #009900">Req0</span>), + +<span style="font-weight: bold"><span style="color: #000000">cowboy_req:stream_body</span></span>(<span style="color: #FF0000">"<html><head>Hello world!</head>"</span>, <span style="color: #FF6600">nofin</span>, <span style="color: #009900">Req</span>), +<span style="font-weight: bold"><span style="color: #000000">cowboy_req:stream_body</span></span>(<span style="color: #FF0000">"<body><p>Hats off!</p></body></html>"</span>, <span style="color: #FF6600">fin</span>, <span style="color: #009900">Req</span>)<span style="color: #990000">.</span></tt></pre></div></div> +<div class="paragraph"><p>HTTP provides a few different ways to stream response bodies. +Cowboy will select the most appropriate one based on the HTTP +version and the request and response headers.</p></div> +<div class="paragraph"><p>While not required by any means, it is recommended that you +set the content-length header in the response if you know it +in advance. This will ensure that the best response method +is selected and help clients understand when the response +is fully received.</p></div> +</div> +</div> +<div class="sect1"> +<h2 id="_preset_response_headers">Preset response headers</h2> +<div class="sectionbody"> +<div class="paragraph"><p>Cowboy provides functions to set response headers without +immediately sending them. They are stored in the Req object +and sent as part of the response when a reply function is +called.</p></div> +<div class="paragraph"><p>To set response headers:</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="color: #009900">Req</span> <span style="color: #990000">=</span> <span style="font-weight: bold"><span style="color: #000000">cowboy_req:set_resp_header</span></span>(<span style="color: #990000"><<</span><span style="color: #FF0000">"allow"</span><span style="color: #990000">>></span>, <span style="color: #FF0000">"GET"</span>, <span style="color: #009900">Req0</span>)<span style="color: #990000">.</span></tt></pre></div></div> +<div class="paragraph"><p>Header names must be a lowercase binary.</p></div> +<div class="paragraph"><p>Do not use this function for setting cookies. Refer to +the <a href="../cookies">Cookies</a> chapter for more information.</p></div> +<div class="paragraph"><p>To check if a response header has already been set:</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">cowboy_req:has_resp_header</span></span>(<span style="color: #990000"><<</span><span style="color: #FF0000">"allow"</span><span style="color: #990000">>></span>, <span style="color: #009900">Req</span>)<span style="color: #990000">.</span></tt></pre></div></div> +<div class="paragraph"><p>It returns <code>true</code> if the header was set, <code>false</code> otherwise.</p></div> +<div class="paragraph"><p>To delete a response header that was set previously:</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="color: #009900">Req</span> <span style="color: #990000">=</span> <span style="font-weight: bold"><span style="color: #000000">cowboy_req:delete_resp_header</span></span>(<span style="color: #990000"><<</span><span style="color: #FF0000">"allow"</span><span style="color: #990000">>></span>, <span style="color: #009900">Req0</span>)<span style="color: #990000">.</span></tt></pre></div></div> +</div> +</div> +<div class="sect1"> +<h2 id="_overriding_headers">Overriding headers</h2> +<div class="sectionbody"> +<div class="paragraph"><p>As Cowboy provides different ways of setting response +headers and body, clashes may occur, so it’s important +to understand what happens when a header is set twice.</p></div> +<div class="paragraph"><p>Headers come from five different origins:</p></div> +<div class="ulist"><ul> +<li> +<p> +Protocol-specific headers (for example HTTP/1.1’s connection header) +</p> +</li> +<li> +<p> +Other required headers (for example the date header) +</p> +</li> +<li> +<p> +Preset headers +</p> +</li> +<li> +<p> +Headers given to the reply function +</p> +</li> +<li> +<p> +Set-cookie headers +</p> +</li> +</ul></div> +<div class="paragraph"><p>Cowboy does not allow overriding protocol-specific headers.</p></div> +<div class="paragraph"><p>Set-cookie headers will always be appended at the end of +the list of headers before sending the response.</p></div> +<div class="paragraph"><p>Headers given to the reply function will always override +preset headers and required headers. If a header is found +in two or three of these, then the one in the reply function +is picked and the others are dropped.</p></div> +<div class="paragraph"><p>Similarly, preset headers will always override required +headers.</p></div> +<div class="paragraph"><p>To illustrate, look at the following snippet. Cowboy by +default sends the server header with the value "Cowboy". +We can override it:</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="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">"server"</span><span style="color: #990000">>></span> <span style="color: #990000">=></span> <span style="color: #990000"><<</span><span style="color: #FF0000">"yaws"</span><span style="color: #990000">>></span> +}, <span style="color: #009900">Req0</span>)<span style="color: #990000">.</span></tt></pre></div></div> +</div> +</div> +<div class="sect1"> +<h2 id="_preset_response_body">Preset response body</h2> +<div class="sectionbody"> +<div class="paragraph"><p>Cowboy provides functions to set the response body without +immediately sending it. It is stored in the Req object and +sent when the reply function is called.</p></div> +<div class="paragraph"><p>To set the response body:</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="color: #009900">Req</span> <span style="color: #990000">=</span> <span style="font-weight: bold"><span style="color: #000000">cowboy_req:set_resp_body</span></span>(<span style="color: #FF0000">"Hello world!"</span>, <span style="color: #009900">Req0</span>)<span style="color: #990000">.</span></tt></pre></div></div> +<div class="paragraph"><p>To check if a response body has already been set:</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">cowboy_req:has_resp_body</span></span>(<span style="color: #009900">Req</span>)<span style="color: #990000">.</span></tt></pre></div></div> +<div class="paragraph"><p>It returns <code>true</code> if the body was set and is non-empty, +<code>false</code> otherwise.</p></div> +<div class="paragraph"><p>The preset response body is only sent if the reply function +used is <code>cowboy_req:reply/2</code> or <code>cowboy_req:reply/3</code>.</p></div> +</div> +</div> +<div class="sect1"> +<h2 id="_sending_files">Sending files</h2> +<div class="sectionbody"> +<div class="paragraph"><p>Cowboy provides a shortcut for sending files. When +using <code>cowboy_req:reply/4</code>, or when presetting the +response header, you can give a <code>sendfile</code> tuple to +Cowboy:</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="color: #FF6600">sendfile</span>, <span style="color: #009900">Offset</span>, <span style="color: #009900">Length</span>, <span style="color: #009900">Filename</span>}</tt></pre></div></div> +<div class="paragraph"><p>Depending on the values for <code>Offset</code> or <code>Length</code>, the +entire file may be sent, or just a part of it.</p></div> +<div class="paragraph"><p>The length is required even for sending the entire file. +Cowboy sends it in the content-length header.</p></div> +<div class="paragraph"><p>To send a file while replying:</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="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: #FF0000">"image/png"</span> +}, {<span style="color: #FF6600">sendfile</span>, <span style="color: #993399">0</span>, <span style="color: #993399">12345</span>, <span style="color: #FF0000">"path/to/logo.png"</span>}, <span style="color: #009900">Req0</span>)<span style="color: #990000">.</span></tt></pre></div></div> +</div> +</div> +<div class="sect1"> +<h2 id="_informational_responses">Informational responses</h2> +<div class="sectionbody"> +<div class="paragraph"><p>Cowboy allows you to send informational responses.</p></div> +<div class="paragraph"><p>Informational responses are responses that have a status +code between 100 and 199. Any number can be sent before +the proper response. Sending an informational response +does not change the behavior of the proper response, and +clients are expected to ignore any informational response +they do not understand.</p></div> +<div class="paragraph"><p>The following snippet sends a 103 informational response +with some headers that are expected to be in the final +response.</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="color: #009900">Req</span> <span style="color: #990000">=</span> <span style="font-weight: bold"><span style="color: #000000">cowboy_req:inform</span></span>(<span style="color: #993399">103</span>, #{ + <span style="color: #990000"><<</span><span style="color: #FF0000">"link"</span><span style="color: #990000">>></span> <span style="color: #990000">=></span> <span style="color: #990000"><<</span><span style="color: #FF0000">"</style.css>; rel=preload; as=style"</span><span style="color: #990000">>></span>, + <span style="color: #990000"><<</span><span style="color: #FF0000">"link"</span><span style="color: #990000">>></span> <span style="color: #990000">=></span> <span style="color: #990000"><<</span><span style="color: #FF0000">"</script.js>; rel=preload; as=script"</span><span style="color: #990000">>></span> +}, <span style="color: #009900">Req0</span>)<span style="color: #990000">.</span></tt></pre></div></div> +</div> +</div> +<div class="sect1"> +<h2 id="_push">Push</h2> +<div class="sectionbody"> +<div class="paragraph"><p>The HTTP/2 protocol introduced the ability to push resources +related to the one sent in the response. Cowboy provides two +functions for that purpose: <code>cowboy_req:push/3,4</code>.</p></div> +<div class="paragraph"><p>Push is only available for HTTP/2. Cowboy will automatically +ignore push requests if the protocol doesn’t support it.</p></div> +<div class="paragraph"><p>The push function must be called before any of the reply +functions. Doing otherwise will result in a crash.</p></div> +<div class="paragraph"><p>To push a resource, you need to provide the same information +as a client performing a request would. This includes the +HTTP method, the URI and any necessary request headers.</p></div> +<div class="paragraph"><p>Cowboy by default only requires you to give the path to +the resource and the request headers. The rest of the URI +is taken from the current request (excluding the query +string, set to empty) and the method is GET by default.</p></div> +<div class="paragraph"><p>The following snippet pushes a CSS file that is linked to +in the response:</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">cowboy_req:push</span></span>(<span style="color: #FF0000">"/static/style.css"</span>, #{ + <span style="color: #990000"><<</span><span style="color: #FF0000">"accept"</span><span style="color: #990000">>></span> <span style="color: #990000">=></span> <span style="color: #990000"><<</span><span style="color: #FF0000">"text/css"</span><span style="color: #990000">>></span> +}, <span style="color: #009900">Req0</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/html"</span><span style="color: #990000">>></span> +}, [<span style="color: #FF0000">"<html><head><title>My web page</title>"</span>, + <span style="color: #FF0000">"<link rel='stylesheet' type='text/css' href='/static/style.css'>"</span>, + <span style="color: #FF0000">"<body><p>Welcome to Erlang!</p></body></html>"</span>], <span style="color: #009900">Req0</span>)<span style="color: #990000">.</span></tt></pre></div></div> +<div class="paragraph"><p>To override the method, scheme, host, port or query string, +simply pass in a fourth argument. The following snippet +uses a different host name:</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">cowboy_req:push</span></span>(<span style="color: #FF0000">"/static/style.css"</span>, #{ + <span style="color: #990000"><<</span><span style="color: #FF0000">"accept"</span><span style="color: #990000">>></span> <span style="color: #990000">=></span> <span style="color: #990000"><<</span><span style="color: #FF0000">"text/css"</span><span style="color: #990000">>></span> +}, #{<span style="color: #0000FF">host</span> <span style="color: #990000">=></span> <span style="color: #990000"><<</span><span style="color: #FF0000">"cdn.example.org"</span><span style="color: #990000">>></span>}, <span style="color: #009900">Req</span>),</tt></pre></div></div> +<div class="paragraph"><p>Pushed resources don’t have to be files. As long as the push +request is cacheable, safe and does not include a body, the +resource can be pushed.</p></div> +<div class="paragraph"><p>Under the hood, Cowboy handles pushed requests the same as +normal requests: a different process is created which will +ultimately send a response to the client.</p></div> +</div> +</div> + + + + + + + + + + + <nav style="margin:1em 0"> + + <a style="float:left" href="https://ninenines.eu/docs/en/cowboy/2.2/guide/req_body/"> + Reading the request body + </a> + + + + <a style="float:right" href="https://ninenines.eu/docs/en/cowboy/2.2/guide/cookies/"> + Using cookies + </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> + + |