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| <title>Configuring HTTP/2 Push</title><link rel="stylesheet" type="text/css" href="css/docbook.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><meta name="keywords" content="jetty, servlet, servlet-api, cometd, http, websocket, eclipse, maven, java, server, software"><link rel="home" href="index.html" title="Jetty"><link rel="up" href="http2.html" title="Chapter 16. HTTP/2"><link rel="prev" href="http2-configuring.html" title="Configuring HTTP/2"><link rel="next" href="http2-configuring-haproxy.html" title="Configuring HAProxy and Jetty"><link xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times" rel="shortcut icon" href="images/favicon.ico"><link rel="stylesheet" href="css/highlighter/foundation.css"><script src="js/highlight.pack.js"></script><script> |
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| Version: 9.4.28-SNAPSHOT</span></td><td style="width: 50%"></td></tr></table><div xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Configuring HTTP/2 Push</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="http2-configuring.html"><i class="fa fa-chevron-left" aria-hidden="true"></i> Previous</a> </td><th width="60%" align="center">Chapter 16. HTTP/2<br><a accesskey="p" href="index.html"><i class="fa fa-home" aria-hidden="true"></i> Home</a></th><td width="20%" align="right"> <a accesskey="n" href="http2-configuring-haproxy.html">Next <i class="fa fa-chevron-right" aria-hidden="true"></i></a></td></tr></table><hr></div><div xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times" class="jetty-callout"><h5 class="callout"><a href="http://www.webtide.com/">Contact the core Jetty developers at |
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| </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="http2-configuring-push"></a>Configuring HTTP/2 Push</h2></div></div></div><p>HTTP/2 Push is a mechanism that allows the server to send multiple resources to the client for a single client request. |
| This will reduce the amount of round-trips necessary to retrieve all the resources that make up a web page and can significantly improve the page load time.</p><p>HTTP/2 Push can be automated in your application by configuring a <a class="link" href="http://www.eclipse.org/jetty/javadoc/9.4.28-SNAPSHOT/org/eclipse/jetty/servlets/PushCacheFilter.html" target="_top"><code class="literal">PushCacheFilter</code></a> in the <code class="literal">web.xml</code>, in this way:</p><pre xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times"><code><?xml version="1.0" encoding="UTF-8"?> |
| <web-app |
| xmlns="http://xmlns.jcp.org/xml/ns/javaee" |
| xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" |
| xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" |
| metadata-complete="true" |
| version="3.1"> |
| |
| ... |
| <filter> |
| <filter-name>PushFilter</filter-name> |
| <filter-class>org.eclipse.jetty.servlets.PushCacheFilter</filter-class> |
| <async-supported>true</async-supported> |
| </filter> |
| <filter-mapping> |
| <filter-name>PushFilter</filter-name> |
| <url-pattern>/*</url-pattern> |
| </filter-mapping> |
| ... |
| |
| </web-app></code></pre><p><code class="literal">PushCacheFilter</code> analyzes the HTTP requests for resources that arrive to your web application. |
| Some of these requests contain the HTTP <code class="literal">Referer</code> header that points to a resource that has been requested previously.</p><p>This allows the <code class="literal">PushCacheFilter</code> to organize resources in a tree, for example a root <code class="literal">index.html</code> resource having two children resources, <code class="literal">styles.css</code> and <code class="literal">application.js</code>, and <code class="literal">styles.css</code> having a child resource, <code class="literal">background.png</code>. |
| The root resource is called the <span class="emphasis"><em>primary</em></span> resource, while descendant resources are called <span class="emphasis"><em>secondary</em></span> resources.</p><p>The resource tree is built using a time window so that when a root resource is requested, only subsequent requests that are made within the time window will be added to the resource tree. |
| The resource tree can also be limited in size so that the number of secondary resources associated to a primary resource is limited.</p><p>By default, only the resource <span class="emphasis"><em>path</em></span> (without the <span class="emphasis"><em>query</em></span> string) is used to associate secondary resources to the primary resource, but you can configure <code class="literal">PushCacheFilter</code> to take the query string into account.</p><p><code class="literal">PushCacheFilter</code> can be configured with the following <code class="literal">init-params</code>:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><code class="literal">associatePeriod</code>: the time window, in milliseconds, within which a request for a secondary resource will be associated to a primary resource; defaults to 4000 ms</li><li class="listitem"><code class="literal">maxAssociations</code>: the max number of secondary resources that may be associated to a primary resource; defaults to 16</li><li class="listitem"><code class="literal">hosts</code>: a comma separated list of hosts that are allowed in the <code class="literal">Referer</code> header; defaults to the host in the <code class="literal">Host</code> header</li><li class="listitem"><code class="literal">ports</code>: a comma separated list of ports that are allowed in the <code class="literal">Referer</code> header; defaults to the port in the <code class="literal">Host</code> header</li><li class="listitem"><code class="literal">useQueryInKey</code>: a boolean indicating whether the query string of the request should be considered when associating secondary resources to primary resources; defaults to <code class="literal">false</code></li></ul></div></div><script type="text/javascript"> |
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