<code>AliasMatch</code> directive:</p><div class="example"><p><code>AliasMatch ^/upages/([a-zA-Z0-9]+)/?(.*)      /home/$1/public_html/$2</code></p></div></div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div><div class="section"><h2><a name="redirect" id="redirect">URL Redirection</a></h2>    <p>The configuration directives discussed in the above sections    tell Apache to get content from a specific place in the filesystem    and return it to the client. Sometimes, it is desirable instead to    inform the client that the requested content is located at a    different URL, and instruct the client to make a new request with    the new URL. This is called <em>redirection</em> and is    implemented by the <code class="directive"><a href="./mod/mod_alias.html#redirect">Redirect</a></code> directive. For example, if    the contents of the directory <code>/foo/</code> under the    <code class="directive"><a href="./mod/core.html#documentroot">DocumentRoot</a></code> are moved    to the new directory <code>/bar/</code>, you can instruct clients    to request the content at the new location as follows:</p><div class="example"><p><code>Redirect permanent /foo/      http://www.example.com/bar/</code></p></div>    <p>This will redirect any URL-Path starting in    <code>/foo/</code> to the same URL path on the    <code>www.example.com</code> server with <code>/bar/</code>    substituted for <code>/foo/</code>. You can redirect clients to    any server, not only the origin server.</p>    <p>Apache also provides a <code class="directive"><a href="./mod/mod_alias.html#redirectmatch">RedirectMatch</a></code> directive for more    complicated rewriting problems. For example, to redirect requests    for the site home page to a different site, but leave all other    requests alone, use the following configuration:</p><div class="example"><p><code>RedirectMatch permanent ^/$      http://www.example.com/startpage.html</code></p></div>    <p>Alternatively, to temporarily redirect all pages on one site    to a particular page on another site, use the following:</p><div class="example"><p><code>RedirectMatch temp .*      http://othersite.example.com/startpage.html</code></p></div></div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div><div class="section"><h2><a name="proxy" id="proxy">Reverse Proxy</a></h2><p>Apache also allows you to bring remote documents into the URL spaceof the local server.  This technique is called <em>reverseproxying</em> because the web server acts like a proxy server byfetching the documents from a remote server and returning them to theclient.  It is different from normal proxying because, to the client,it appears the documents originate at the reverse proxy server.</p><p>In the following example, when clients request documents under the<code>/foo/</code> directory, the server fetches those documents fromthe <code>/bar/</code> directory on <code>internal.example.com</code>and returns them to the client as if they were from the localserver.</p><div class="example"><p><code>ProxyPass /foo/ http://internal.example.com/bar/<br />ProxyPassReverse /foo/ http://internal.example.com/bar/</code></p></div><p>The <code class="directive"><a href="./mod/mod_proxy.html#proxypass">ProxyPass</a></code> configuresthe server to fetch the appropriate documents, while the<code class="directive"><a href="./mod/mod_proxy.html#proxypassreverse">ProxyPassReverse</a></code>directive rewrites redirects originating at<code>internal.example.com</code> so that they target the appropriatedirectory on the local server.  It is important to note, however, thatlinks inside the documents will not be rewritten.  So any absolutelinks on <code>internal.example.com</code> will result in the clientbreaking out of the proxy server and requesting directly from<code>internal.example.com</code>.</p></div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div><div class="section"><h2><a name="rewrite" id="rewrite">Rewriting Engine</a></h2>    <p>When even more powerful substitution is required, the rewriting    engine provided by <code class="module"><a href="./mod/mod_rewrite.html">mod_rewrite</a></code>    can be useful. The directives provided by this module use    characteristics of the request such as browser type or source IP    address in deciding from where to serve content. In addition,    mod_rewrite can use external database files or programs to    determine how to handle a request. The rewriting engine is capable    of performing all three types of mappings discussed above:    internal redirects (aliases), external redirects, and proxying.    Many practical examples employing mod_rewrite are discussed in the    <a href="misc/rewriteguide.html">URL Rewriting Guide</a>.</p></div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div><div class="section"><h2><a name="notfound" id="notfound">File Not Found</a></h2>    <p>Inevitably, URLs will be requested for which no matching    file can be found in the filesystem. This can happen for    several reasons. In some cases, it can be a result of moving    documents from one location to another. In this case, it is    best to use <a href="#redirect">URL redirection</a> to inform    clients of the new location of the resource. In this way, you    can assure that old bookmarks and links will continue to work,    even though the resource is at a new location.</p>    <p>Another common cause of "File Not Found" errors is    accidental mistyping of URLs, either directly in the browser,    or in HTML links. Apache provides the module    <code class="module"><a href="./mod/mod_speling.html">mod_speling</a></code> (sic) to help with    this problem. When this module is activated, it will intercept    "File Not Found" errors and look for a resource with a similar    filename. If one such file is found, mod_speling will send an    HTTP redirect to the client informing it of the correct    location. If several "close" files are found, a list of    available alternatives will be presented to the client.</p>    <p>An especially useful feature of mod_speling, is that it will    compare filenames without respect to case. This can help    systems where users are unaware of the case-sensitive nature of    URLs and the unix filesystem. But using mod_speling for    anything more than the occasional URL correction can place    additional load on the server, since each "incorrect" request    is followed by a URL redirection and a new request from the    client.</p>    <p>If all attempts to locate the content fail, Apache returns    an error page with HTTP status code 404 (file not found). The    appearance of this page is controlled with the    <code class="directive"><a href="./mod/core.html#errordocument">ErrorDocument</a></code> directive    and can be customized in a flexible manner as discussed in the    <a href="custom-error.html">Custom error responses</a> and <a href="misc/custom_errordocs.html">International Server Error    Responses</a> documents.</p></div></div><div class="bottomlang"><p><span>Available Languages: </span><a href="./en/urlmapping.html" title="English">&nbsp;en&nbsp;</a> |<a href="./ja/urlmapping.html" hreflang="ja" rel="alternate" title="Japanese">&nbsp;ja&nbsp;</a> |<a href="./ko/urlmapping.html" hreflang="ko" rel="alternate" title="Korean">&nbsp;ko&nbsp;</a></p></div><div id="footer"><p class="apache">Copyright 1995-2005 The Apache Software Foundation or its licensors, as applicable.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p><p class="menu"><a href="./mod/">Modules</a> | <a href="./mod/directives.html">Directives</a> | <a href="./faq/">FAQ</a> | <a href="./glossary.html">Glossary</a> | <a href="./sitemap.html">Sitemap</a></p></div></body></html>