2014-04-01-http-209.html

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layout: reveal
title: HTTP 209
description: W3C TAG F2F April 2014
author: Jeni Tennison
twitter: JeniT
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<section>
	<section>
		<h2>Problem</h2>
	</section>
	<section>
		<img src="2014-04-01-http-209/resources.png">
	</section>
	<section>
		<h3>Parts of large resources</h3>
		<pre><code class="http">GET /really-big-map HTTP/1.1</code></pre>
		<pre><code class="http">HTTP/1.1 303 See Other
Location: /small.png
Link: &lt;/small.png&gt;; rel=preview</code></pre>
	</section>
	<section>
		<h3>Pages of a collection</h3>
		<pre><code class="http">GET /long-running-blog HTTP/1.1</code></pre>
		<pre><code class="http">HTTP/1.1 303 See Other
Location: /first-page
Link: &lt;/first-page&gt;; rel=start</code></pre>
	</section>
	<section>
		<h3>Descriptions of non-information resources</h3>
		<pre><code class="http">GET /tim-berners-lee HTTP/1.1</code></pre>
		<pre><code class="http">HTTP/1.1 303 See Other
Location: http://en.wikipedia.org/wiki/Tim_Berners-Lee
Link: &lt;http://en.wikipedia.org/wiki/Tim_Berners-Lee&gt;; rel=describedby</code></pre>
	</section>
	<section>
		<h3>Why not 303?</h3>
		<ul>
			<li>303s mean two roundtrips</li>
			<li>increases latency</li>
			<li>(legacy) lack of caching</li>
			<li>provides the wrong URL for links</li>
		</ul>
	</section>
</section>

<section>
	<section>
		<h2>Proposal</h2>
	</section>
	<section>
		<h3>209 Contents of Related</h3>
		<p><a href="http://www.w3.org/2014/02/2xx/draft-prudhommeaux-http-status-209">http://www.w3.org/2014/02/2xx/draft-prudhommeaux-http-status-209</a></p>
		<p>from discussions of Linked Data Platform Working Group</p>
		<pre><code class="http">GET /really-big-map HTTP/1.1</code></pre>
		<pre><code class="http">HTTP/1.1 209 Contents of Related
Location: /small.png</code></pre>
	</section>
	<section>
		<h3>Issues</h3>
		<ul>
			<li>which resource do headers apply to?</li>
			<li>how do apps that only recognise 200 react?</li>
			<li>how does a server know which clients understand?</li>
		</ul>
	</section>
	<section>
		<h3>Alternatives</h3>
		<ul>
			<li>link to directly the related resource</li>
			<li><a href="http://lists.w3.org/Archives/Public/www-tag/2014Mar/0003.html">use <code>Content-Location</code></a></li>
			<li>use the content of the response to detail relationship</li>
			<li>use <a href="http://tools.ietf.org/html/draft-ietf-httpbis-http2-10#section-8.2">HTTP 2.0 Server Push</a></li>
		</ul>
	</section>
</section>

<section>
	<section>
		<h2>Process</h2>
	</section>
	<section>
		<h3>Via IETF</h3>
		<p>Internet Draft</p>
	</section>
</section>