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   <title>Cross Origin Filter</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="advanced-extras.html" title="Chapter&nbsp;18.&nbsp;Provided Servlets, Filters, and Handlers"><link rel="prev" href="gzip-filter.html" title="Gzip Handler"><link rel="next" href="resource-handler.html" title="Resource Handler"><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: 9.3.28.v20191105</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">Cross Origin Filter</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="gzip-filter.html"><i class="fa fa-chevron-left" aria-hidden="true"></i> Previous</a>&nbsp;</td><th width="60%" align="center">Chapter&nbsp;18.&nbsp;Provided Servlets, Filters, and Handlers<br><a accesskey="p" href="index.html"><i class="fa fa-home" aria-hidden="true"></i> Home</a></th><td width="20%" align="right">&nbsp;<a accesskey="n" href="resource-handler.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="cross-origin-filter"></a>Cross Origin Filter</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="cross-origin-filter.html#cross-origin-filter-metadata">Info</a></span></dt><dt><span class="section"><a href="cross-origin-filter.html#cross-origin-filter-usage">Usage</a></span></dt><dt><span class="section"><a href="cross-origin-filter.html#cross-origin-setup">Setup</a></span></dt><dt><span class="section"><a href="cross-origin-filter.html#cross-origin-config">Configuration</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="cross-origin-filter-metadata"></a>Info</h3></div></div></div><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Classname: <code class="literal">org.eclipse.jetty.servlets.CrossOriginFilter</code></li><li class="listitem">Maven Artifact: org.eclipse.jetty:jetty-servlets</li><li class="listitem">Javadoc: <a class="link" href="http://www.eclipse.org/jetty/javadoc/9.3.28.v20191105/org/eclipse/jetty/servlets/CrossOriginFilter.html" target="_top">http://www.eclipse.org/jetty/javadoc/9.3.28.v20191105/org/eclipse/jetty/servlets/CrossOriginFilter.html</a></li></ul></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="cross-origin-filter-usage"></a>Usage</h3></div></div></div><p>HTTP requests made from a script are subject to well known restrictions, the most prominent being the same domain policy.</p><p>Firefox 3.5 introduced support for W3C&#8217;s Access Control for Cross-Site Requests specification, which requires a compliant client (for example, Firefox 3.5) and a compliant server (via this servlet filter).</p><p>This filter implements the required bits to support the server-side contract of the specification, and will allow a compliant client to perform cross-domain requests via the standard XMLHttpRequest object.
If the client does not issue a compliant cross-domain request, this filter does nothing, and its overhead is the check of the presence of the cross-domain HTTP header.</p><p>This is extremely useful in CometD web applications where it is now possible to perform cross-domain long polling without using script injection (also known as the JSONP transport), and therefore removing all the downsides that the JSONP transport has (it&#8217;s chattier, does not react quickly to failures, has a message size limit, uses GET instead of POST, etc.).</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="cross-origin-setup"></a>Setup</h3></div></div></div><p>You will need to put the <code class="literal">jetty-servlets.jar</code> file onto your classpath.
If you are creating a webapp, ensure that this jar is included in your webapp&#8217;s <code class="literal">WEB-INF/lib</code>.
Or, if you are running Jetty embedded you will need to ensure that <code class="literal">jetty-servlets.jar</code> is on the execution classpath.
You can download the <code class="literal">jetty-servlets.jar</code> from the Maven Central Repository at <a class="link" href="http://central.maven.org/maven2/org/eclipse/jetty/jetty-servlets/" target="_top">http://central.maven.org/maven2/org/eclipse/jetty/jetty-servlets/</a>.
It is also available as part of the Jetty distribution in the <code class="literal">$JETTY_HOME/lib</code> directory.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="cross-origin-config"></a>Configuration</h3></div></div></div><p>This is a regular servlet filter that must be configured in <code class="literal">web.xml</code>.</p><p>It supports the following configuration parameters:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term">allowedOrigins</span></dt><dd>A comma separated list of origins that are allowed to access the resources.
Default value is: * (all origins)</dd><dt><span class="term">allowedMethods</span></dt><dd>A comma separated list of HTTP methods that are allowed to be used when accessing the resources.
Default value is: GET,POST,HEAD</dd><dt><span class="term">allowedHeaders</span></dt><dd>A comma separated list of HTTP headers that are allowed to be specified when accessing the resources.
Default value is: X-Requested-With,Content-Type,Accept,Origin</dd><dt><span class="term">allowCredentials</span></dt><dd>A boolean indicating if the resource allows requests with credentials.
Default value is: true</dd><dt><span class="term">preflightMaxAge</span></dt><dd>The number of seconds that preflight requests can be cached by the client.
Default value is 1800 seconds (30 minutes)</dd><dt><span class="term">chainPreflight</span></dt><dd>If true preflight requests are chained to their target resource for normal handling (as an OPTION request).
Otherwise the filter will response to the preflight.
Default is true.</dd><dt><span class="term">exposedHeaders</span></dt><dd>A comma separated list of HTTP headers that are allowed to be exposed on the client.
Default value is the empty list.</dd></dl></div><p>A typical configuration could be:</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>&lt;web-app&gt;

    &lt;filter&gt;
        &lt;filter-name&gt;cross-origin&lt;/filter-name&gt;
        &lt;filter-class&gt;org.eclipse.jetty.servlets.CrossOriginFilter&lt;/filter-class&gt;
    &lt;/filter&gt;
    &lt;filter-mapping&gt;
        &lt;filter-name&gt;cross-origin&lt;/filter-name&gt;
        &lt;url-pattern&gt;/cometd/*&lt;/url-pattern&gt;
    &lt;/filter-mapping&gt;

&lt;/web-app&gt;</code></pre></div></div><script type="text/javascript">
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