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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<title>mod_proxy_ajp - Apache HTTP Server Version 2.5</title>
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<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
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<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" />
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</script>
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<link href="../images/favicon.ico" rel="shortcut icon" /></head>
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<body>
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<div id="page-header">
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<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/quickreference.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p>
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<p class="apache">Apache HTTP Server Version 2.5</p>
|
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<img alt="" src="../images/feather.png" /></div>
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<div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div>
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<div id="path">
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<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.5</a> > <a href="./">Modules</a></div>
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<div id="page-content">
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<div id="preamble"><h1>Apache Module mod_proxy_ajp</h1>
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<div class="toplang">
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<p><span>Available Languages: </span><a href="../en/mod/mod_proxy_ajp.html" title="English"> en </a> |
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<a href="../fr/mod/mod_proxy_ajp.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
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<a href="../ja/mod/mod_proxy_ajp.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a></p>
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</div>
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<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>AJP support module for
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<code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code></td></tr>
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<tr><th><a href="module-dict.html#Status">Status:</a></th><td>Extension</td></tr>
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<tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>proxy_ajp_module</td></tr>
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<tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>mod_proxy_ajp.c</td></tr></table>
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<h3>Summary</h3>
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||
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<p>This module <em>requires</em> the service of <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>. It provides support for the
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<code>Apache JServ Protocol version 1.3</code> (hereafter
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<em>AJP13</em>).</p>
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<p>Thus, in order to get the ability of handling <code>AJP13</code>
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protocol, <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> and
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<code class="module"><a href="../mod/mod_proxy_ajp.html">mod_proxy_ajp</a></code> have to be present in the server.</p>
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<div class="warning"><h3>Warning</h3>
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<p>Do not enable proxying until you have <a href="mod_proxy.html#access">secured your server</a>. Open proxy
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servers are dangerous both to your network and to the Internet at
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large.</p>
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</div>
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</div>
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<div id="quickview"><h3>Topics</h3>
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<ul id="topics">
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<li><img alt="" src="../images/down.gif" /> <a href="#usage">Usage</a></li>
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||
<li><img alt="" src="../images/down.gif" /> <a href="#env">Environment Variables</a></li>
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||
<li><img alt="" src="../images/down.gif" /> <a href="#overviewprotocol">Overview of the protocol</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#basppacketstruct">Basic Packet Structure</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#rpacetstruct">Request Packet Structure</a></li>
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<li><img alt="" src="../images/down.gif" /> <a href="#resppacketstruct">Response Packet Structure</a></li>
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</ul><h3 class="directives">Directives</h3>
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<p>This module provides no
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directives.</p>
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<h3>Bugfix checklist</h3><ul class="seealso"><li><a href="https://www.apache.org/dist/httpd/CHANGES_2.4">httpd changelog</a></li><li><a href="https://bz.apache.org/bugzilla/buglist.cgi?bug_status=__open__&list_id=144532&product=Apache%20httpd-2&query_format=specific&order=changeddate%20DESC%2Cpriority%2Cbug_severity&component=mod_proxy_ajp">Known issues</a></li><li><a href="https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2&component=mod_proxy_ajp">Report a bug</a></li></ul><h3>See also</h3>
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||
<ul class="seealso">
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||
<li><code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code></li>
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||
<li><a href="../env.html">Environment Variable documentation</a></li>
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||
<li><a href="#comments_section">Comments</a></li></ul></div>
|
||
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
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||
<div class="section">
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||
<h2><a name="usage" id="usage">Usage</a> <a title="Permanent link" href="#usage" class="permalink">¶</a></h2>
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<p>This module is used to reverse proxy to a backend application server
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(e.g. Apache Tomcat) using the AJP13 protocol. The usage is similar to
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an HTTP reverse proxy, but uses the <code>ajp://</code> prefix:</p>
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||
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<div class="example"><h3>Simple Reverse Proxy</h3><pre class="prettyprint lang-config">ProxyPass "/app" "ajp://backend.example.com:8009/app"</pre>
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</div>
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<p>Options such as the <code>secret</code> option of Tomcat (required by
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default since Tomcat 8.5.51 and 9.0.31) can just be added as a separate
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parameter at the end of <code class="directive"><a href="../mod/mod_proxy.html#proxypass">ProxyPass</a></code>
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or <code class="directive"><a href="../mod/mod_proxy.html#balancermember">BalancerMember</a></code>. This parameter
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is available in Apache HTTP Server 2.4.42 and later:</p>
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<div class="example"><h3>Simple Reverse Proxy with <code>secret</code> option</h3><pre class="prettyprint lang-config">ProxyPass "/app" "ajp://backend.example.com:8009/app" secret=YOUR_AJP_SECRET</pre>
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</div>
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<p>Balancers may also be used:</p>
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<div class="example"><h3>Balancer Reverse Proxy</h3><pre class="prettyprint lang-config"><Proxy "balancer://cluster">
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BalancerMember "ajp://app1.example.com:8009" loadfactor=1
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BalancerMember "ajp://app2.example.com:8009" loadfactor=2
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ProxySet lbmethod=bytraffic
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</Proxy>
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ProxyPass "/app" "balancer://cluster/app"</pre>
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</div>
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<p>Note that usually no
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<code class="directive"><a href="../mod/mod_proxy.html#proxypassreverse">ProxyPassReverse</a></code>
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directive is necessary. The AJP request includes the original host
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header given to the proxy, and the application server can be expected
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to generate self-referential headers relative to this host, so no
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rewriting is necessary.</p>
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<p>The main exception is when the URL path on the proxy differs from that
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on the
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backend. In this case, a redirect header can be rewritten relative to the
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original host URL (not the backend <code>ajp://</code> URL), for
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example:</p>
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<div class="example"><h3>Rewriting Proxied Path</h3><pre class="prettyprint lang-config">ProxyPass "/apps/foo" "ajp://backend.example.com:8009/foo"
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ProxyPassReverse "/apps/foo" "http://www.example.com/foo"</pre>
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</div>
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<p>However, it is usually better to deploy the application on the backend
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server at the same path as the proxy rather than to take this approach.
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</p>
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</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
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<div class="section">
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<h2><a name="env" id="env">Environment Variables</a> <a title="Permanent link" href="#env" class="permalink">¶</a></h2>
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<p>Environment variables whose names have the prefix <code>AJP_</code>
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are forwarded to the origin server as AJP request attributes
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(with the <code>AJP_</code> prefix removed from the name of the key).</p>
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</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
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<div class="section">
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<h2><a name="overviewprotocol" id="overviewprotocol">Overview of the protocol</a> <a title="Permanent link" href="#overviewprotocol" class="permalink">¶</a></h2>
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<p>The <code>AJP13</code> protocol is packet-oriented. A binary format
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was presumably chosen over the more readable plain text for reasons of
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performance. The web server communicates with the servlet container over
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TCP connections. To cut down on the expensive process of socket creation,
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the web server will attempt to maintain persistent TCP connections to the
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servlet container, and to reuse a connection for multiple request/response
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cycles.</p>
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<p>Once a connection is assigned to a particular request, it will not be
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used for any others until the request-handling cycle has terminated. In
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other words, requests are not multiplexed over connections. This makes
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for much simpler code at either end of the connection, although it does
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cause more connections to be open at once.</p>
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<p>Once the web server has opened a connection to the servlet container,
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the connection can be in one of the following states:</p>
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<ul>
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<li> Idle <br /> No request is being handled over this connection. </li>
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<li> Assigned <br /> The connection is handling a specific request.</li>
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</ul>
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<p>Once a connection is assigned to handle a particular request, the basic
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request information (e.g. HTTP headers, etc) is sent over the connection in
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a highly condensed form (e.g. common strings are encoded as integers).
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Details of that format are below in Request Packet Structure. If there is a
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body to the request <code>(content-length > 0)</code>, that is sent in a
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separate packet immediately after.</p>
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<p>At this point, the servlet container is presumably ready to start
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processing the request. As it does so, it can send the
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following messages back to the web server:</p>
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<ul>
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<li>SEND_HEADERS <br />Send a set of headers back to the browser.</li>
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<li>SEND_BODY_CHUNK <br />Send a chunk of body data back to the browser.
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</li>
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<li>GET_BODY_CHUNK <br />Get further data from the request if it hasn't all
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been transferred yet. This is necessary because the packets have a fixed
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maximum size and arbitrary amounts of data can be included the body of a
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request (for uploaded files, for example). (Note: this is unrelated to
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HTTP chunked transfer).</li>
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||
<li>END_RESPONSE <br /> Finish the request-handling cycle.</li>
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||
</ul>
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<p>Each message is accompanied by a differently formatted packet of data.
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See Response Packet Structures below for details.</p>
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</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
|
||
<div class="section">
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||
<h2><a name="basppacketstruct" id="basppacketstruct">Basic Packet Structure</a> <a title="Permanent link" href="#basppacketstruct" class="permalink">¶</a></h2>
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||
<p>There is a bit of an XDR heritage to this protocol, but it differs
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in lots of ways (no 4 byte alignment, for example).</p>
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<p>AJP13 uses network byte order for all data types.</p>
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<p>There are four data types in the protocol: bytes, booleans,
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integers and strings.</p>
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<dl>
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<dt><strong>Byte</strong></dt><dd>A single byte.</dd>
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<dt><strong>Boolean</strong></dt>
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<dd>A single byte, <code>1 = true</code>, <code>0 = false</code>.
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Using other non-zero values as true (i.e. C-style) may work in some places,
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but it won't in others.</dd>
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<dt><strong>Integer</strong></dt>
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<dd>A number in the range of <code>0 to 2^16 (32768)</code>. Stored in
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2 bytes with the high-order byte first.</dd>
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<dt><strong>String</strong></dt>
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<dd>A variable-sized string (length bounded by 2^16). Encoded with
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the length packed into two bytes first, followed by the string
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(including the terminating '\0'). Note that the encoded length does
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<strong>not</strong> include the trailing '\0' -- it is like
|
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<code>strlen</code>. This is a touch confusing on the Java side, which
|
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is littered with odd autoincrement statements to skip over these
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terminators. I believe the reason this was done was to allow the C
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||
code to be extra efficient when reading strings which the servlet
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||
container is sending back -- with the terminating \0 character, the
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C code can pass around references into a single buffer, without copying.
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if the \0 was missing, the C code would have to copy things out in order
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||
to get its notion of a string.</dd>
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</dl>
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<h3>Packet Size</h3>
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<p>According to much of the code, the max packet size is <code>
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8 * 1024 bytes (8K)</code>. The actual length of the packet is encoded in
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the header.</p>
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<h3>Packet Headers</h3>
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<p>Packets sent from the server to the container begin with
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<code>0x1234</code>. Packets sent from the container to the server
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begin with <code>AB</code> (that's the ASCII code for A followed by the
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ASCII code for B). After those first two bytes, there is an integer
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(encoded as above) with the length of the payload. Although this might
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suggest that the maximum payload could be as large as 2^16, in fact, the
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code sets the maximum to be 8K.</p>
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<table>
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<tr>
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<th colspan="6"><em>Packet Format (Server->Container)</em></th>
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</tr>
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<tr>
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<th>Byte</th>
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<td>0</td>
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<td>1</td>
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<td>2</td>
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<td>3</td>
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<td>4...(n+3)</td>
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</tr>
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<tr>
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<th>Contents</th>
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<td>0x12</td>
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<td>0x34</td>
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<td colspan="2">Data Length (n)</td>
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<td>Data</td>
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</tr>
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||
</table>
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<table>
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<tr>
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<th colspan="6"><em>Packet Format (Container->Server)</em></th>
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</tr>
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<tr>
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<th>Byte</th>
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<td>0</td>
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||
<td>1</td>
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||
<td>2</td>
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||
<td>3</td>
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<td>4...(n+3)</td>
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||
</tr>
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||
<tr>
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||
<th>Contents</th>
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||
<td>A</td>
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<td>B</td>
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<td colspan="2">Data Length (n)</td>
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<td>Data</td>
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||
</tr>
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||
</table>
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<p>For most packets, the first byte of the payload encodes the type of
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||
message. The exception is for request body packets sent from the server to
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the container -- they are sent with a standard packet header (<code>
|
||
0x1234</code> and then length of the packet), but without any prefix code
|
||
after that.</p>
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||
<p>The web server can send the following messages to the servlet
|
||
container:</p>
|
||
<table>
|
||
|
||
<tr>
|
||
<td>Code</td>
|
||
<td>Type of Packet</td>
|
||
<td>Meaning</td>
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||
</tr>
|
||
<tr>
|
||
<td>2</td>
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<td>Forward Request</td>
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||
<td>Begin the request-processing cycle with the following data</td>
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||
</tr>
|
||
<tr>
|
||
<td>7</td>
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||
<td>Shutdown</td>
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||
<td>The web server asks the container to shut itself down.</td>
|
||
</tr>
|
||
<tr>
|
||
<td>8</td>
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<td>Ping</td>
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||
<td>The web server asks the container to take control
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||
(secure login phase).</td>
|
||
</tr>
|
||
<tr>
|
||
<td>10</td>
|
||
<td>CPing</td>
|
||
<td>The web server asks the container to respond quickly with a CPong.
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td>none</td>
|
||
<td>Data</td>
|
||
<td>Size (2 bytes) and corresponding body data.</td>
|
||
</tr>
|
||
</table>
|
||
<p>To ensure some basic security, the container will only actually do the
|
||
<code>Shutdown</code> if the request comes from the same machine on which
|
||
it's hosted.</p>
|
||
<p>The first <code>Data</code> packet is send immediately after the
|
||
<code>Forward Request</code> by the web server.</p>
|
||
<p>The servlet container can send the following types of messages to the
|
||
webserver:</p>
|
||
<table>
|
||
|
||
<tr>
|
||
<td>Code</td>
|
||
<td>Type of Packet</td>
|
||
<td>Meaning</td>
|
||
</tr>
|
||
<tr>
|
||
<td>3</td>
|
||
<td>Send Body Chunk</td>
|
||
<td>Send a chunk of the body from the servlet container to the web
|
||
server (and presumably, onto the browser). </td>
|
||
</tr>
|
||
<tr>
|
||
<td>4</td>
|
||
<td>Send Headers</td>
|
||
<td>Send the response headers from the servlet container to the web
|
||
server (and presumably, onto the browser).</td>
|
||
</tr>
|
||
<tr>
|
||
<td>5</td>
|
||
<td>End Response</td>
|
||
<td>Marks the end of the response (and thus the request-handling cycle).
|
||
</td>
|
||
</tr>
|
||
<tr>
|
||
<td>6</td>
|
||
<td>Get Body Chunk</td>
|
||
<td>Get further data from the request if it hasn't all been
|
||
transferred yet.</td>
|
||
</tr>
|
||
<tr>
|
||
<td>9</td>
|
||
<td>CPong Reply</td>
|
||
<td>The reply to a CPing request</td>
|
||
</tr>
|
||
</table>
|
||
<p>Each of the above messages has a different internal structure, detailed
|
||
below.</p>
|
||
|
||
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
|
||
<div class="section">
|
||
<h2><a name="rpacetstruct" id="rpacetstruct">Request Packet Structure</a> <a title="Permanent link" href="#rpacetstruct" class="permalink">¶</a></h2>
|
||
<p>For messages from the server to the container of type
|
||
<em>Forward Request</em>:</p>
|
||
<div class="example"><pre>AJP13_FORWARD_REQUEST :=
|
||
prefix_code (byte) 0x02 = JK_AJP13_FORWARD_REQUEST
|
||
method (byte)
|
||
protocol (string)
|
||
req_uri (string)
|
||
remote_addr (string)
|
||
remote_host (string)
|
||
server_name (string)
|
||
server_port (integer)
|
||
is_ssl (boolean)
|
||
num_headers (integer)
|
||
request_headers *(req_header_name req_header_value)
|
||
attributes *(attribut_name attribute_value)
|
||
request_terminator (byte) OxFF</pre></div>
|
||
<p>The <code>request_headers</code> have the following structure:
|
||
</p><div class="example"><pre>req_header_name :=
|
||
sc_req_header_name | (string) [see below for how this is parsed]
|
||
|
||
sc_req_header_name := 0xA0xx (integer)
|
||
|
||
req_header_value := (string)</pre></div>
|
||
<p>The <code>attributes</code> are optional and have the following
|
||
structure:</p>
|
||
<div class="example"><pre>attribute_name := sc_a_name | (sc_a_req_attribute string)
|
||
|
||
attribute_value := (string)</pre></div>
|
||
<p>Not that the all-important header is <code>content-length</code>,
|
||
because it determines whether or not the container looks for another
|
||
packet immediately.</p>
|
||
<h3>Detailed description of the elements of Forward Request
|
||
</h3>
|
||
<h3>Request prefix</h3>
|
||
<p>For all requests, this will be 2. See above for details on other Prefix
|
||
codes.</p>
|
||
|
||
<h3>Method</h3>
|
||
<p>The HTTP method, encoded as a single byte:</p>
|
||
<table>
|
||
<tr><td>Command Name</td><td>Code</td></tr>
|
||
<tr><td>OPTIONS</td><td>1</td></tr>
|
||
<tr><td>GET</td><td>2</td></tr>
|
||
<tr><td>HEAD</td><td>3</td></tr>
|
||
<tr><td>POST</td><td>4</td></tr>
|
||
<tr><td>PUT</td><td>5</td></tr>
|
||
<tr><td>DELETE</td><td>6</td></tr>
|
||
<tr><td>TRACE</td><td>7</td></tr>
|
||
<tr><td>PROPFIND</td><td>8</td></tr>
|
||
<tr><td>PROPPATCH</td><td>9</td></tr>
|
||
<tr><td>MKCOL</td><td>10</td></tr>
|
||
<tr><td>COPY</td><td>11</td></tr>
|
||
<tr><td>MOVE</td><td>12</td></tr>
|
||
<tr><td>LOCK</td><td>13</td></tr>
|
||
<tr><td>UNLOCK</td><td>14</td></tr>
|
||
<tr><td>ACL</td><td>15</td></tr>
|
||
<tr><td>REPORT</td><td>16</td></tr>
|
||
<tr><td>VERSION-CONTROL</td><td>17</td></tr>
|
||
<tr><td>CHECKIN</td><td>18</td></tr>
|
||
<tr><td>CHECKOUT</td><td>19</td></tr>
|
||
<tr><td>UNCHECKOUT</td><td>20</td></tr>
|
||
<tr><td>SEARCH</td><td>21</td></tr>
|
||
<tr><td>MKWORKSPACE</td><td>22</td></tr>
|
||
<tr><td>UPDATE</td><td>23</td></tr>
|
||
<tr><td>LABEL</td><td>24</td></tr>
|
||
<tr><td>MERGE</td><td>25</td></tr>
|
||
<tr><td>BASELINE_CONTROL</td><td>26</td></tr>
|
||
<tr><td>MKACTIVITY</td><td>27</td></tr>
|
||
</table>
|
||
<p>Later version of ajp13, will transport
|
||
additional methods, even if they are not in this list.</p>
|
||
|
||
<h3>protocol, req_uri, remote_addr, remote_host, server_name,
|
||
server_port, is_ssl</h3>
|
||
<p>These are all fairly self-explanatory. Each of these is required, and
|
||
will be sent for every request.</p>
|
||
|
||
<h3>Headers</h3>
|
||
<p>The structure of <code>request_headers</code> is the following:
|
||
First, the number of headers <code>num_headers</code> is encoded.
|
||
Then, a series of header name <code>req_header_name</code> / value
|
||
<code>req_header_value</code> pairs follows.
|
||
Common header names are encoded as integers,
|
||
to save space. If the header name is not in the list of basic headers,
|
||
it is encoded normally (as a string, with prefixed length). The list of
|
||
common headers <code>sc_req_header_name</code>and their codes
|
||
is as follows (all are case-sensitive):</p>
|
||
<table>
|
||
<tr><td>Name</td><td>Code value</td><td>Code name</td></tr>
|
||
<tr><td>accept</td><td>0xA001</td><td>SC_REQ_ACCEPT</td></tr>
|
||
<tr><td>accept-charset</td><td>0xA002</td><td>SC_REQ_ACCEPT_CHARSET
|
||
</td></tr>
|
||
<tr><td>accept-encoding</td><td>0xA003</td><td>SC_REQ_ACCEPT_ENCODING
|
||
</td></tr>
|
||
<tr><td>accept-language</td><td>0xA004</td><td>SC_REQ_ACCEPT_LANGUAGE
|
||
</td></tr>
|
||
<tr><td>authorization</td><td>0xA005</td><td>SC_REQ_AUTHORIZATION</td>
|
||
</tr>
|
||
<tr><td>connection</td><td>0xA006</td><td>SC_REQ_CONNECTION</td></tr>
|
||
<tr><td>content-type</td><td>0xA007</td><td>SC_REQ_CONTENT_TYPE</td>
|
||
</tr>
|
||
<tr><td>content-length</td><td>0xA008</td><td>SC_REQ_CONTENT_LENGTH</td>
|
||
</tr>
|
||
<tr><td>cookie</td><td>0xA009</td><td>SC_REQ_COOKIE</td></tr>
|
||
<tr><td>cookie2</td><td>0xA00A</td><td>SC_REQ_COOKIE2</td></tr>
|
||
<tr><td>host</td><td>0xA00B</td><td>SC_REQ_HOST</td></tr>
|
||
<tr><td>pragma</td><td>0xA00C</td><td>SC_REQ_PRAGMA</td></tr>
|
||
<tr><td>referer</td><td>0xA00D</td><td>SC_REQ_REFERER</td></tr>
|
||
<tr><td>user-agent</td><td>0xA00E</td><td>SC_REQ_USER_AGENT</td></tr>
|
||
</table>
|
||
<p>The Java code that reads this grabs the first two-byte integer and if
|
||
it sees an <code>'0xA0'</code> in the most significant
|
||
byte, it uses the integer in the second byte as an index into an array of
|
||
header names. If the first byte is not <code>0xA0</code>, it assumes that
|
||
the two-byte integer is the length of a string, which is then read in.</p>
|
||
<p>This works on the assumption that no header names will have length
|
||
greater than <code>0x9FFF (==0xA000 - 1)</code>, which is perfectly
|
||
reasonable, though somewhat arbitrary.</p>
|
||
<div class="note"><h3>Note:</h3>
|
||
The <code>content-length</code> header is extremely
|
||
important. If it is present and non-zero, the container assumes that
|
||
the request has a body (a POST request, for example), and immediately
|
||
reads a separate packet off the input stream to get that body.
|
||
</div>
|
||
|
||
<h3>Attributes</h3>
|
||
<p>The attributes prefixed with a <code>?</code>
|
||
(e.g. <code>?context</code>) are all optional. For each, there is a
|
||
single byte code to indicate the type of attribute, and then its value
|
||
(string or integer). They can be sent in any order (though the C code
|
||
always sends them in the order listed below). A special terminating code
|
||
is sent to signal the end of the list of optional attributes. The list of
|
||
byte codes is:</p>
|
||
<table>
|
||
<tr><td>Information</td><td>Code Value</td><td>Type Of Value</td><td>Note</td></tr>
|
||
<tr><td>?context</td><td>0x01</td><td>-</td><td>Not currently implemented
|
||
</td></tr>
|
||
<tr><td>?servlet_path</td><td>0x02</td><td>-</td><td>Not currently implemented
|
||
</td></tr>
|
||
<tr><td>?remote_user</td><td>0x03</td><td>String</td><td /></tr>
|
||
<tr><td>?auth_type</td><td>0x04</td><td>String</td><td /></tr>
|
||
<tr><td>?query_string</td><td>0x05</td><td>String</td><td /></tr>
|
||
<tr><td>?jvm_route</td><td>0x06</td><td>String</td><td /></tr>
|
||
<tr><td>?ssl_cert</td><td>0x07</td><td>String</td><td /></tr>
|
||
<tr><td>?ssl_cipher</td><td>0x08</td><td>String</td><td /></tr>
|
||
<tr><td>?ssl_session</td><td>0x09</td><td>String</td><td /></tr>
|
||
<tr><td>?req_attribute</td><td>0x0A</td><td>String</td><td>Name (the name of the
|
||
attribute follows)</td></tr>
|
||
<tr><td>?ssl_key_size</td><td>0x0B</td><td>Integer</td><td /></tr>
|
||
<tr><td>?secret</td><td>0x0C</td><td>String</td><td>Supported since 2.4.42</td></tr>
|
||
<tr><td>are_done</td><td>0xFF</td><td>-</td><td>request_terminator</td></tr>
|
||
</table>
|
||
<p>The <code>context</code> and <code>servlet_path</code> are not
|
||
currently set by the C code, and most of the Java code completely ignores
|
||
whatever is sent over for those fields (and some of it will actually break
|
||
if a string is sent along after one of those codes). I don't know if this
|
||
is a bug or an unimplemented feature or just vestigial code, but it's
|
||
missing from both sides of the connection.</p>
|
||
<p>The <code>remote_user</code> and <code>auth_type</code> presumably
|
||
refer to HTTP-level authentication, and communicate the remote user's
|
||
username and the type of authentication used to establish their identity
|
||
(e.g. Basic, Digest).</p>
|
||
<p>The <code>query_string</code>, <code>ssl_cert</code>,
|
||
<code>ssl_cipher</code>, <code>ssl_session</code> and
|
||
<code>ssl_key_size</code> refer to the
|
||
corresponding pieces of HTTP and HTTPS.</p>
|
||
<p>The <code>jvm_route</code>, is used to support sticky
|
||
sessions -- associating a user's sesson with a particular Tomcat instance
|
||
in the presence of multiple, load-balancing servers.</p>
|
||
<p>The <code>secret</code> is sent when the <code>secret=secret_keyword</code>
|
||
parameter is used in
|
||
<code class="directive"><a href="../mod/mod_proxy.html#proxypass">ProxyPass</a></code> or
|
||
<code class="directive"><a href="../mod/mod_proxy.html#balancermember">BalancerMember</a></code> directives.
|
||
The backend needs to support secret and the values must match.
|
||
<code>request.secret</code> or <code>requiredSecret</code> are documented in the AJP
|
||
configuration of the Apache Tomcat.</p>
|
||
<p>Beyond this list of basic attributes, any number of other attributes
|
||
can be sent via the <code>req_attribute</code> code <code>0x0A</code>.
|
||
A pair of strings to represent the attribute name and value are sent
|
||
immediately after each instance of that code. Environment values are passed
|
||
in via this method.</p>
|
||
<p>Finally, after all the attributes have been sent, the attribute
|
||
terminator, <code>0xFF</code>, is sent. This signals both the end of the
|
||
list of attributes and also then end of the Request Packet.</p>
|
||
|
||
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
|
||
<div class="section">
|
||
<h2><a name="resppacketstruct" id="resppacketstruct">Response Packet Structure</a> <a title="Permanent link" href="#resppacketstruct" class="permalink">¶</a></h2>
|
||
<p>for messages which the container can send back to the server.</p>
|
||
<div class="example"><pre>AJP13_SEND_BODY_CHUNK :=
|
||
prefix_code 3
|
||
chunk_length (integer)
|
||
chunk *(byte)
|
||
chunk_terminator (byte) Ox00
|
||
|
||
|
||
AJP13_SEND_HEADERS :=
|
||
prefix_code 4
|
||
http_status_code (integer)
|
||
http_status_msg (string)
|
||
num_headers (integer)
|
||
response_headers *(res_header_name header_value)
|
||
|
||
res_header_name :=
|
||
sc_res_header_name | (string) [see below for how this is parsed]
|
||
|
||
sc_res_header_name := 0xA0 (byte)
|
||
|
||
header_value := (string)
|
||
|
||
AJP13_END_RESPONSE :=
|
||
prefix_code 5
|
||
reuse (boolean)
|
||
|
||
|
||
AJP13_GET_BODY_CHUNK :=
|
||
prefix_code 6
|
||
requested_length (integer)</pre></div>
|
||
<h3>Details:</h3>
|
||
<h3>Send Body Chunk</h3>
|
||
<p>The chunk is basically binary data, and is sent directly back to the
|
||
browser.</p>
|
||
|
||
<h3>Send Headers</h3>
|
||
<p>The status code and message are the usual HTTP things
|
||
(e.g. <code>200</code> and <code>OK</code>). The response header names are
|
||
encoded the same way the request header names are. See header_encoding above
|
||
for details about how the codes are distinguished from the strings.<br />
|
||
The codes for common headers are:</p>
|
||
<table>
|
||
<tr><td>Name</td><td>Code value</td></tr>
|
||
<tr><td>Content-Type</td><td>0xA001</td></tr>
|
||
<tr><td>Content-Language</td><td>0xA002</td></tr>
|
||
<tr><td>Content-Length</td><td>0xA003</td></tr>
|
||
<tr><td>Date</td><td>0xA004</td></tr>
|
||
<tr><td>Last-Modified</td><td>0xA005</td></tr>
|
||
<tr><td>Location</td><td>0xA006</td></tr>
|
||
<tr><td>Set-Cookie</td><td>0xA007</td></tr>
|
||
<tr><td>Set-Cookie2</td><td>0xA008</td></tr>
|
||
<tr><td>Servlet-Engine</td><td>0xA009</td></tr>
|
||
<tr><td>Status</td><td>0xA00A</td></tr>
|
||
<tr><td>WWW-Authenticate</td><td>0xA00B</td></tr>
|
||
</table>
|
||
<p> After the code or the string header name, the header value is
|
||
immediately encoded.</p>
|
||
|
||
<h3>End Response</h3>
|
||
<p>Signals the end of this request-handling cycle. If the
|
||
<code>reuse</code> flag is true <code>(anything other than 0 in the actual
|
||
C code)</code>, this TCP connection can now be used to handle new incoming
|
||
requests. If <code>reuse</code> is false (==0), the connection should
|
||
be closed.</p>
|
||
|
||
<h3>Get Body Chunk</h3>
|
||
<p>The container asks for more data from the request (If the body was
|
||
too large to fit in the first packet sent over or when the request is
|
||
chunked). The server will send a body packet back with an amount of data
|
||
which is the minimum of the <code>request_length</code>, the maximum send
|
||
body size <code>(8186 (8 Kbytes - 6))</code>, and the number of bytes
|
||
actually left to send from the request body.<br />
|
||
If there is no more data in the body (i.e. the servlet container is
|
||
trying to read past the end of the body), the server will send back an
|
||
<em>empty</em> packet, which is a body packet with a payload length of 0.
|
||
<code>(0x12,0x34,0x00,0x00)</code></p>
|
||
|
||
</div>
|
||
</div>
|
||
<div class="bottomlang">
|
||
<p><span>Available Languages: </span><a href="../en/mod/mod_proxy_ajp.html" title="English"> en </a> |
|
||
<a href="../fr/mod/mod_proxy_ajp.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
|
||
<a href="../ja/mod/mod_proxy_ajp.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a></p>
|
||
</div><div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed by our moderators if they are either implemented or considered invalid/off-topic. Questions on how to manage the Apache HTTP Server should be directed at either our IRC channel, #httpd, on Libera.chat, or sent to our <a href="https://httpd.apache.org/lists.html">mailing lists</a>.</div>
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