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<h1 class="refname">http_cache_etag</h1>
<p class="verinfo">(PECL pecl_http >= 0.1.0)</p><p class="refpurpose"><span class="refname">http_cache_etag</span> — <span class="dc-title">Caching by ETag</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.http-cache-etag-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">bool</span> <span class="methodname"><strong>http_cache_etag</strong></span>
([ <span class="methodparam"><span class="type">string</span> <code class="parameter">$etag</code></span>
] )</div>
<p class="para rdfs-comment">
Attempts to cache the sent entity by its <em>ETag</em>, either supplied or generated
by the hash algorithm specified by the <a href="http.configuration.html" class="link">INI setting</a>
<a href="" class="link">http.etag.mode</a>.
</p>
<p class="para">
If the clients <em>If-None-Match</em> header matches the supplied/calculated
ETag, the body is considered cached on the clients side and
a <em>304 Not Modified</em> status code is issued.
</p>
<p class="para">
A log entry is written to the cache log if the <a href="http.configuration.html" class="link">INI setting</a>
<a href="" class="link">http.log.cache</a> is set
and the cache attempt was successful.
</p>
<blockquote class="note"><p><strong class="note">Note</strong>: <span class="simpara">This function may be used in conjunction with
<span class="function"><a href="function.http-send-data.html" class="function">http_send_data()</a></span>, <span class="function"><a href="function.http-send-file.html" class="function">http_send_file()</a></span> and <span class="function"><a href="function.http-send-stream.html" class="function">http_send_stream()</a></span>.</span></p></blockquote>
<p class="para">
If this function is used outside the http_send_*() API, it facilitates the <span class="function"><a href="function.ob-etaghandler.html" class="function">ob_etaghandler()</a></span>.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.http-cache-etag-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">etag</code></em></span>
<dd>
<p class="para">
custom <em>ETag</em>
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.http-cache-etag-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns <strong><code>FALSE</code></strong> or <em class="emphasis">exits</em> on success with <em>304 Not Modified</em> if the entity is cached.
See the <a href="http.configuration.html" class="link">INI setting</a>
<a href="" class="link">http.force_exit</a> for what "exits" means.
</p>
</div>
<div class="refsect1 examples" id="refsect1-function.http-cache-etag-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-4358">
<p><strong>Example #1 A <span class="function"><strong>http_cache_etag()</strong></span> example</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />http_cache_etag</span><span style="color: #007700">();<br /></span><span style="color: #0000BB">http_send_data</span><span style="color: #007700">(</span><span style="color: #DD0000">"data"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
</div>
<div class="refsect1 seealso" id="refsect1-function.http-cache-etag-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="function"><a href="function.http-cache-last-modified.html" class="function" rel="rdfs-seeAlso">http_cache_last_modified()</a> - Caching by last modification</span></li>
<li class="member"> <span class="function"><a href="function.ob-etaghandler.html" class="function" rel="rdfs-seeAlso">ob_etaghandler()</a> - ETag output handler</span></li>
<li class="member"> <span class="function"><a href="function.http-match-etag.html" class="function" rel="rdfs-seeAlso">http_match_etag()</a> - Match ETag</span></li>
<li class="member">the <a href="class.httpresponse.html" class="link">
<a href="class.httpresponse.html" class="classname">HttpResponse</a></a> class if you are using PHP 5.1.0
and above</li>
</ul>
</p>
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