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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 15:01:30 +0000 |
|---|---|---|
| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 15:01:30 +0000 |
| commit | 6beeb1b708550be0d4a53b272283e17e5e35fe17 (patch) | |
| tree | 1ce8673d4aaa948e5554000101f46536a1e4cc29 /docs/manual/mod/mod_proxy_ajp.html.en | |
| parent | Initial commit. (diff) | |
| download | apache2-upstream/2.4.57.tar.xz apache2-upstream/2.4.57.zip | |
Adding upstream version 2.4.57.upstream/2.4.57
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
| -rw-r--r-- | docs/manual/mod/mod_proxy_ajp.html.en | 639 |
1 files changed, 639 insertions, 0 deletions
diff --git a/docs/manual/mod/mod_proxy_ajp.html.en b/docs/manual/mod/mod_proxy_ajp.html.en new file mode 100644 index 0000000..1d8cb01 --- /dev/null +++ b/docs/manual/mod/mod_proxy_ajp.html.en @@ -0,0 +1,639 @@ +<?xml version="1.0" encoding="UTF-8"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head> +<meta content="text/html; charset=UTF-8" http-equiv="Content-Type" /> +<!-- + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + This file is generated from xml source: DO NOT EDIT + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + --> +<title>mod_proxy_ajp - Apache HTTP Server Version 2.4</title> +<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" /> +<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" /> +<link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link rel="stylesheet" type="text/css" href="../style/css/prettify.css" /> +<script src="../style/scripts/prettify.min.js" type="text/javascript"> +</script> + +<link href="../images/favicon.ico" rel="shortcut icon" /></head> +<body> +<div id="page-header"> +<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.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> +<p class="apache">Apache HTTP Server Version 2.4</p> +<img alt="" src="../images/feather.png" /></div> +<div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div> +<div id="path"> +<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 2.4</a> > <a href="./">Modules</a></div> +<div id="page-content"> +<div id="preamble"><h1>Apache Module mod_proxy_ajp</h1> +<div class="toplang"> +<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> +<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>AJP support module for +<code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code></td></tr> +<tr><th><a href="module-dict.html#Status">Status:</a></th><td>Extension</td></tr> +<tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>proxy_ajp_module</td></tr> +<tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>mod_proxy_ajp.c</td></tr> +<tr><th><a href="module-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.1 and later</td></tr></table> +<h3>Summary</h3> + + <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 + <code>Apache JServ Protocol version 1.3</code> (hereafter + <em>AJP13</em>).</p> + + <p>Thus, in order to get the ability of handling <code>AJP13</code> + protocol, <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> and + <code class="module"><a href="../mod/mod_proxy_ajp.html">mod_proxy_ajp</a></code> have to be present in the server.</p> + + <div class="warning"><h3>Warning</h3> + <p>Do not enable proxying until you have <a href="mod_proxy.html#access">secured your server</a>. Open proxy + servers are dangerous both to your network and to the Internet at + large.</p> + </div> +</div> +<div id="quickview"><a href="https://www.apache.org/foundation/contributing.html" class="badge"><img src="https://www.apache.org/images/SupportApache-small.png" alt="Support Apache!" /></a><h3>Topics</h3> +<ul id="topics"> +<li><img alt="" src="../images/down.gif" /> <a href="#usage">Usage</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#env">Environment Variables</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#overviewprotocol">Overview of the protocol</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#basppacketstruct">Basic Packet Structure</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#rpacetstruct">Request Packet Structure</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#resppacketstruct">Response Packet Structure</a></li> +</ul><h3 class="directives">Directives</h3> +<p>This module provides no + directives.</p> +<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> +<ul class="seealso"> +<li><code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code></li> +<li><a href="../env.html">Environment Variable documentation</a></li> +<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> +<div class="section"> +<h2><a name="usage" id="usage">Usage</a></h2> + <p>This module is used to reverse proxy to a backend application server + (e.g. Apache Tomcat) using the AJP13 protocol. The usage is similar to + an HTTP reverse proxy, but uses the <code>ajp://</code> prefix:</p> + + <div class="example"><h3>Simple Reverse Proxy</h3><pre class="prettyprint lang-config">ProxyPass "/app" "ajp://backend.example.com:8009/app"</pre> +</div> + + <p>Options such as the <code>secret</code> option of Tomcat (required by + default since Tomcat 8.5.51 and 9.0.31) can just be added as a separate + parameter at the end of <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>. This parameter + is available in Apache HTTP Server 2.4.42 and later:</p> + <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> +</div> + + <p>Balancers may also be used:</p> + <div class="example"><h3>Balancer Reverse Proxy</h3><pre class="prettyprint lang-config"><Proxy "balancer://cluster"> + BalancerMember "ajp://app1.example.com:8009" loadfactor=1 + BalancerMember "ajp://app2.example.com:8009" loadfactor=2 + ProxySet lbmethod=bytraffic +</Proxy> +ProxyPass "/app" "balancer://cluster/app"</pre> +</div> + + <p>Note that usually no + <code class="directive"><a href="../mod/mod_proxy.html#proxypassreverse">ProxyPassReverse</a></code> + directive is necessary. The AJP request includes the original host + header given to the proxy, and the application server can be expected + to generate self-referential headers relative to this host, so no + rewriting is necessary.</p> + + <p>The main exception is when the URL path on the proxy differs from that + on the + backend. In this case, a redirect header can be rewritten relative to the + original host URL (not the backend <code>ajp://</code> URL), for + example:</p> + <div class="example"><h3>Rewriting Proxied Path</h3><pre class="prettyprint lang-config">ProxyPass "/apps/foo" "ajp://backend.example.com:8009/foo" +ProxyPassReverse "/apps/foo" "http://www.example.com/foo"</pre> +</div> + <p>However, it is usually better to deploy the application on the backend + server at the same path as the proxy rather than to take this approach. + </p> +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="env" id="env">Environment Variables</a></h2> + <p>Environment variables whose names have the prefix <code>AJP_</code> + are forwarded to the origin server as AJP request attributes + (with the <code>AJP_</code> prefix removed from the name of the key).</p> +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="overviewprotocol" id="overviewprotocol">Overview of the protocol</a></h2> + <p>The <code>AJP13</code> protocol is packet-oriented. A binary format + was presumably chosen over the more readable plain text for reasons of + performance. The web server communicates with the servlet container over + TCP connections. To cut down on the expensive process of socket creation, + the web server will attempt to maintain persistent TCP connections to the + servlet container, and to reuse a connection for multiple request/response + cycles.</p> + <p>Once a connection is assigned to a particular request, it will not be + used for any others until the request-handling cycle has terminated. In + other words, requests are not multiplexed over connections. This makes + for much simpler code at either end of the connection, although it does + cause more connections to be open at once.</p> + <p>Once the web server has opened a connection to the servlet container, + the connection can be in one of the following states:</p> + <ul> + <li> Idle <br /> No request is being handled over this connection. </li> + <li> Assigned <br /> The connection is handling a specific request.</li> + </ul> + <p>Once a connection is assigned to handle a particular request, the basic + request information (e.g. HTTP headers, etc) is sent over the connection in + a highly condensed form (e.g. common strings are encoded as integers). + Details of that format are below in Request Packet Structure. If there is a + body to the request <code>(content-length > 0)</code>, that is sent in a + separate packet immediately after.</p> + <p>At this point, the servlet container is presumably ready to start + processing the request. As it does so, it can send the + following messages back to the web server:</p> + <ul> + <li>SEND_HEADERS <br />Send a set of headers back to the browser.</li> + <li>SEND_BODY_CHUNK <br />Send a chunk of body data back to the browser. + </li> + <li>GET_BODY_CHUNK <br />Get further data from the request if it hasn't all + been transferred yet. This is necessary because the packets have a fixed + maximum size and arbitrary amounts of data can be included the body of a + request (for uploaded files, for example). (Note: this is unrelated to + HTTP chunked transfer).</li> + <li>END_RESPONSE <br /> Finish the request-handling cycle.</li> + </ul> + <p>Each message is accompanied by a differently formatted packet of data. + See Response Packet Structures below for details.</p> +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="basppacketstruct" id="basppacketstruct">Basic Packet Structure</a></h2> + <p>There is a bit of an XDR heritage to this protocol, but it differs + in lots of ways (no 4 byte alignment, for example).</p> + <p>AJP13 uses network byte order for all data types.</p> + <p>There are four data types in the protocol: bytes, booleans, + integers and strings.</p> + <dl> + <dt><strong>Byte</strong></dt><dd>A single byte.</dd> + <dt><strong>Boolean</strong></dt> + <dd>A single byte, <code>1 = true</code>, <code>0 = false</code>. + Using other non-zero values as true (i.e. C-style) may work in some places, + but it won't in others.</dd> + <dt><strong>Integer</strong></dt> + <dd>A number in the range of <code>0 to 2^16 (32768)</code>. Stored in + 2 bytes with the high-order byte first.</dd> + <dt><strong>String</strong></dt> + <dd>A variable-sized string (length bounded by 2^16). Encoded with + the length packed into two bytes first, followed by the string + (including the terminating '\0'). Note that the encoded length does + <strong>not</strong> include the trailing '\0' -- it is like + <code>strlen</code>. This is a touch confusing on the Java side, which + is littered with odd autoincrement statements to skip over these + terminators. I believe the reason this was done was to allow the C + code to be extra efficient when reading strings which the servlet + container is sending back -- with the terminating \0 character, the + C code can pass around references into a single buffer, without copying. + if the \0 was missing, the C code would have to copy things out in order + to get its notion of a string.</dd> + </dl> + + <h3>Packet Size</h3> + <p>According to much of the code, the max packet size is <code> + 8 * 1024 bytes (8K)</code>. The actual length of the packet is encoded in + the header.</p> + + <h3>Packet Headers</h3> + <p>Packets sent from the server to the container begin with + <code>0x1234</code>. Packets sent from the container to the server + begin with <code>AB</code> (that's the ASCII code for A followed by the + ASCII code for B). After those first two bytes, there is an integer + (encoded as above) with the length of the payload. Although this might + suggest that the maximum payload could be as large as 2^16, in fact, the + code sets the maximum to be 8K.</p> + <table> + + <tr> + <th colspan="6"><em>Packet Format (Server->Container)</em></th> + </tr> + <tr> + <th>Byte</th> + <td>0</td> + <td>1</td> + <td>2</td> + <td>3</td> + <td>4...(n+3)</td> + </tr> + <tr> + <th>Contents</th> + <td>0x12</td> + <td>0x34</td> + <td colspan="2">Data Length (n)</td> + <td>Data</td> + </tr> + </table> + <table> + + <tr> + <th colspan="6"><em>Packet Format (Container->Server)</em></th> + </tr> + <tr> + <th>Byte</th> + <td>0</td> + <td>1</td> + <td>2</td> + <td>3</td> + <td>4...(n+3)</td> + </tr> + <tr> + <th>Contents</th> + <td>A</td> + <td>B</td> + <td colspan="2">Data Length (n)</td> + <td>Data</td> + </tr> + </table> + <p>For most packets, the first byte of the payload encodes the type of + message. The exception is for request body packets sent from the server to + 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> + <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> + </tr> + <tr> + <td>2</td> + <td>Forward Request</td> + <td>Begin the request-processing cycle with the following data</td> + </tr> + <tr> + <td>7</td> + <td>Shutdown</td> + <td>The web server asks the container to shut itself down.</td> + </tr> + <tr> + <td>8</td> + <td>Ping</td> + <td>The web server asks the container to take control + (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></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></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. 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