1<?xml version="1.0" encoding="ISO-8859-1"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head><!-- 4 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 5 This file is generated from xml source: DO NOT EDIT 6 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 7 --> 8<title>mod_proxy_ajp - Apache HTTP Server</title> 9<link href="/style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" /> 10<link href="/style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" /> 11<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" /> 12<script src="/style/scripts/prettify.min.js" type="text/javascript"> 13</script> 14 15<link href="/images/favicon.ico" rel="shortcut icon" /></head> 16<body> 17<div id="page-header"> 18<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> 19<p class="apache">Apache HTTP Server Version 2.4</p> 20<img alt="" src="/images/feather.gif" /></div> 21<div class="up"><a href="./"><img title="<-" alt="<-" src="/images/left.gif" /></a></div> 22<div id="path"> 23<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> 24<div id="page-content"> 25<div id="preamble"><h1>Apache Module mod_proxy_ajp</h1> 26<div class="toplang"> 27<p><span>Available Languages: </span><a href="/en/mod/mod_proxy_ajp.html" title="English"> en </a> | 28<a href="/fr/mod/mod_proxy_ajp.html" hreflang="fr" rel="alternate" title="Fran�ais"> fr </a> | 29<a href="/ja/mod/mod_proxy_ajp.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a></p> 30</div> 31<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>AJP support module for 32<code class="module"><a href="/mod/mod_proxy.html">mod_proxy</a></code></td></tr> 33<tr><th><a href="module-dict.html#Status">Status:</a></th><td>Extension</td></tr> 34<tr><th><a href="module-dict.html#ModuleIdentifier">Module�Identifier:</a></th><td>proxy_ajp_module</td></tr> 35<tr><th><a href="module-dict.html#SourceFile">Source�File:</a></th><td>mod_proxy_ajp.c</td></tr> 36<tr><th><a href="module-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.1 and later</td></tr></table> 37<h3>Summary</h3> 38 39 <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 40 <code>Apache JServ Protocol version 1.3</code> (hereafter 41 <em>AJP13</em>).</p> 42 43 <p>Thus, in order to get the ability of handling <code>AJP13</code> 44 protocol, <code class="module"><a href="/mod/mod_proxy.html">mod_proxy</a></code> and 45 <code class="module"><a href="/mod/mod_proxy_ajp.html">mod_proxy_ajp</a></code> have to be present in the server.</p> 46 47 <div class="warning"><h3>Warning</h3> 48 <p>Do not enable proxying until you have <a href="mod_proxy.html#access">secured your server</a>. Open proxy 49 servers are dangerous both to your network and to the Internet at 50 large.</p> 51 </div> 52</div> 53<div id="quickview"><h3 class="directives">Directives</h3> 54<p>This module provides no 55 directives.</p> 56<h3>Topics</h3> 57<ul id="topics"> 58<li><img alt="" src="/images/down.gif" /> <a href="#usage">Usage</a></li> 59<li><img alt="" src="/images/down.gif" /> <a href="#env">Environment Variables</a></li> 60<li><img alt="" src="/images/down.gif" /> <a href="#overviewprotocol">Overview of the protocol</a></li> 61<li><img alt="" src="/images/down.gif" /> <a href="#basppacketstruct">Basic Packet Structure</a></li> 62<li><img alt="" src="/images/down.gif" /> <a href="#rpacetstruct">Request Packet Structure</a></li> 63<li><img alt="" src="/images/down.gif" /> <a href="#resppacketstruct">Response Packet Structure</a></li> 64</ul><h3>See also</h3> 65<ul class="seealso"> 66<li><code class="module"><a href="/mod/mod_proxy.html">mod_proxy</a></code></li> 67<li><a href="/env.html">Environment Variable documentation</a></li> 68</ul><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div> 69<div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 70<div class="section"> 71<h2><a name="usage" id="usage">Usage</a></h2> 72 <p>This module is used to reverse proxy to a backend application server 73 (e.g. Apache Tomcat) using the AJP13 protocol. The usage is similar to 74 an HTTP reverse proxy, but uses the <code>ajp://</code> prefix:</p> 75 76 <div class="example"><h3>Simple Reverse Proxy</h3><pre class="prettyprint lang-config">ProxyPass /app ajp://backend.example.com:8009/app</pre> 77</div> 78 79 <p>Balancers may also be used:</p> 80 <div class="example"><h3>Balancer Reverse Proxy</h3><pre class="prettyprint lang-config"><Proxy balancer://cluster> 81 BalancerMember ajp://app1.example.com:8009 loadfactor=1 82 BalancerMember ajp://app2.example.com:8009 loadfactor=2 83 ProxySet lbmethod=bytraffic 84</Proxy> 85ProxyPass /app balancer://cluster/app</pre> 86</div> 87 88 <p>Note that usually no 89 <code class="directive"><a href="/mod/mod_proxy.html#proxypassreverse">ProxyPassReverse</a></code> 90 directive is necessary. The AJP request includes the original host 91 header given to the proxy, and the application server can be expected 92 to generate self-referential headers relative to this host, so no 93 rewriting is necessary.</p> 94 95 <p>The main exception is when the URL path on the proxy differs from that 96 on the 97 backend. In this case, a redirect header can be rewritten relative to the 98 original host URL (not the backend <code>ajp://</code> URL), for 99 example:</p> 100 <div class="example"><h3>Rewriting Proxied Path</h3><pre class="prettyprint lang-config">ProxyPass /apps/foo ajp://backend.example.com:8009/foo 101ProxyPassReverse /apps/foo http://www.example.com/foo</pre> 102</div> 103 <p>However, it is usually better to deploy the application on the backend 104 server at the same path as the proxy rather than to take this approach. 105 </p> 106</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 107<div class="section"> 108<h2><a name="env" id="env">Environment Variables</a></h2> 109 <p>Environment variables whose names have the prefix <code>AJP_</code> 110 are forwarded to the origin server as AJP request attributes 111 (with the AJP_ prefix removed from the name of the key).</p> 112</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 113<div class="section"> 114<h2><a name="overviewprotocol" id="overviewprotocol">Overview of the protocol</a></h2> 115 <p>The <code>AJP13</code> protocol is packet-oriented. A binary format 116 was presumably chosen over the more readable plain text for reasons of 117 performance. The web server communicates with the servlet container over 118 TCP connections. To cut down on the expensive process of socket creation, 119 the web server will attempt to maintain persistent TCP connections to the 120 servlet container, and to reuse a connection for multiple request/response 121 cycles.</p> 122 <p>Once a connection is assigned to a particular request, it will not be 123 used for any others until the request-handling cycle has terminated. In 124 other words, requests are not multiplexed over connections. This makes 125 for much simpler code at either end of the connection, although it does 126 cause more connections to be open at once.</p> 127 <p>Once the web server has opened a connection to the servlet container, 128 the connection can be in one of the following states:</p> 129 <ul> 130 <li> Idle <br /> No request is being handled over this connection. </li> 131 <li> Assigned <br /> The connection is handling a specific request.</li> 132 </ul> 133 <p>Once a connection is assigned to handle a particular request, the basic 134 request information (e.g. HTTP headers, etc) is sent over the connection in 135 a highly condensed form (e.g. common strings are encoded as integers). 136 Details of that format are below in Request Packet Structure. If there is a 137 body to the request <code>(content-length > 0)</code>, that is sent in a 138 separate packet immediately after.</p> 139 <p>At this point, the servlet container is presumably ready to start 140 processing the request. As it does so, it can send the 141 following messages back to the web server:</p> 142 <ul> 143 <li>SEND_HEADERS <br />Send a set of headers back to the browser.</li> 144 <li>SEND_BODY_CHUNK <br />Send a chunk of body data back to the browser. 145 </li> 146 <li>GET_BODY_CHUNK <br />Get further data from the request if it hasn't all 147 been transferred yet. This is necessary because the packets have a fixed 148 maximum size and arbitrary amounts of data can be included the body of a 149 request (for uploaded files, for example). (Note: this is unrelated to 150 HTTP chunked transfer).</li> 151 <li>END_RESPONSE <br /> Finish the request-handling cycle.</li> 152 </ul> 153 <p>Each message is accompanied by a differently formatted packet of data. 154 See Response Packet Structures below for details.</p> 155</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 156<div class="section"> 157<h2><a name="basppacketstruct" id="basppacketstruct">Basic Packet Structure</a></h2> 158 <p>There is a bit of an XDR heritage to this protocol, but it differs 159 in lots of ways (no 4 byte alignment, for example).</p> 160 <p>Byte order: I am not clear about the endian-ness of the individual 161 bytes. I'm guessing the bytes are little-endian, because that's what 162 XDR specifies, and I'm guessing that sys/socket library is magically 163 making that so (on the C side). If anyone with a better knowledge of 164 socket calls can step in, that would be great.</p> 165 <p>There are four data types in the protocol: bytes, booleans, 166 integers and strings.</p> 167 <dl> 168 <dt><strong>Byte</strong></dt><dd>A single byte.</dd> 169 <dt><strong>Boolean</strong></dt> 170 <dd>A single byte, <code>1 = true</code>, <code>0 = false</code>. 171 Using other non-zero values as true (i.e. C-style) may work in some places, 172 but it won't in others.</dd> 173 <dt><strong>Integer</strong></dt> 174 <dd>A number in the range of <code>0 to 2^16 (32768)</code>. Stored in 175 2 bytes with the high-order byte first.</dd> 176 <dt><strong>String</strong></dt> 177 <dd>A variable-sized string (length bounded by 2^16). Encoded with 178 the length packed into two bytes first, followed by the string 179 (including the terminating '\0'). Note that the encoded length does 180 <strong>not</strong> include the trailing '\0' -- it is like 181 <code>strlen</code>. This is a touch confusing on the Java side, which 182 is littered with odd autoincrement statements to skip over these 183 terminators. I believe the reason this was done was to allow the C 184 code to be extra efficient when reading strings which the servlet 185 container is sending back -- with the terminating \0 character, the 186 C code can pass around references into a single buffer, without copying. 187 if the \0 was missing, the C code would have to copy things out in order 188 to get its notion of a string.</dd> 189 </dl> 190 191 <h3>Packet Size</h3> 192 <p>According to much of the code, the max packet size is <code> 193 8 * 1024 bytes (8K)</code>. The actual length of the packet is encoded in 194 the header.</p> 195 196 <h3>Packet Headers</h3> 197 <p>Packets sent from the server to the container begin with 198 <code>0x1234</code>. Packets sent from the container to the server 199 begin with <code>AB</code> (that's the ASCII code for A followed by the 200 ASCII code for B). After those first two bytes, there is an integer 201 (encoded as above) with the length of the payload. Although this might 202 suggest that the maximum payload could be as large as 2^16, in fact, the 203 code sets the maximum to be 8K.</p> 204 <table> 205 206 <tr> 207 <th colspan="6"><em>Packet Format (Server->Container)</em></th> 208 </tr> 209 <tr> 210 <th>Byte</th> 211 <td>0</td> 212 <td>1</td> 213 <td>2</td> 214 <td>3</td> 215 <td>4...(n+3)</td> 216 </tr> 217 <tr> 218 <th>Contents</th> 219 <td>0x12</td> 220 <td>0x34</td> 221 <td colspan="2">Data Length (n)</td> 222 <td>Data</td> 223 </tr> 224 </table> 225 <table> 226 227 <tr> 228 <th colspan="6"><em>Packet Format (Container->Server)</em></th> 229 </tr> 230 <tr> 231 <th>Byte</th> 232 <td>0</td> 233 <td>1</td> 234 <td>2</td> 235 <td>3</td> 236 <td>4...(n+3)</td> 237 </tr> 238 <tr> 239 <th>Contents</th> 240 <td>A</td> 241 <td>B</td> 242 <td colspan="2">Data Length (n)</td> 243 <td>Data</td> 244 </tr> 245 </table> 246 <p>For most packets, the first byte of the payload encodes the type of 247 message. The exception is for request body packets sent from the server to 248 the container -- they are sent with a standard packet header (<code> 249 0x1234</code> and then length of the packet), but without any prefix code 250 after that.</p> 251 <p>The web server can send the following messages to the servlet 252 container:</p> 253 <table> 254 255 <tr> 256 <td>Code</td> 257 <td>Type of Packet</td> 258 <td>Meaning</td> 259 </tr> 260 <tr> 261 <td>2</td> 262 <td>Forward Request</td> 263 <td>Begin the request-processing cycle with the following data</td> 264 </tr> 265 <tr> 266 <td>7</td> 267 <td>Shutdown</td> 268 <td>The web server asks the container to shut itself down.</td> 269 </tr> 270 <tr> 271 <td>8</td> 272 <td>Ping</td> 273 <td>The web server asks the container to take control 274 (secure login phase).</td> 275 </tr> 276 <tr> 277 <td>10</td> 278 <td>CPing</td> 279 <td>The web server asks the container to respond quickly with a CPong. 280 </td> 281 </tr> 282 <tr> 283 <td>none</td> 284 <td>Data</td> 285 <td>Size (2 bytes) and corresponding body data.</td> 286 </tr> 287 </table> 288 <p>To ensure some basic security, the container will only actually do the 289 <code>Shutdown</code> if the request comes from the same machine on which 290 it's hosted.</p> 291 <p>The first <code>Data</code> packet is send immediately after the 292 <code>Forward Request</code> by the web server.</p> 293 <p>The servlet container can send the following types of messages to the 294 webserver:</p> 295 <table> 296 297 <tr> 298 <td>Code</td> 299 <td>Type of Packet</td> 300 <td>Meaning</td> 301 </tr> 302 <tr> 303 <td>3</td> 304 <td>Send Body Chunk</td> 305 <td>Send a chunk of the body from the servlet container to the web 306 server (and presumably, onto the browser). </td> 307 </tr> 308 <tr> 309 <td>4</td> 310 <td>Send Headers</td> 311 <td>Send the response headers from the servlet container to the web 312 server (and presumably, onto the browser).</td> 313 </tr> 314 <tr> 315 <td>5</td> 316 <td>End Response</td> 317 <td>Marks the end of the response (and thus the request-handling cycle). 318 </td> 319 </tr> 320 <tr> 321 <td>6</td> 322 <td>Get Body Chunk</td> 323 <td>Get further data from the request if it hasn't all been 324 transferred yet.</td> 325 </tr> 326 <tr> 327 <td>9</td> 328 <td>CPong Reply</td> 329 <td>The reply to a CPing request</td> 330 </tr> 331 </table> 332 <p>Each of the above messages has a different internal structure, detailed 333 below.</p> 334 335</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 336<div class="section"> 337<h2><a name="rpacetstruct" id="rpacetstruct">Request Packet Structure</a></h2> 338 <p>For messages from the server to the container of type 339 <em>Forward Request</em>:</p> 340 <div class="example"><pre>AJP13_FORWARD_REQUEST := 341 prefix_code (byte) 0x02 = JK_AJP13_FORWARD_REQUEST 342 method (byte) 343 protocol (string) 344 req_uri (string) 345 remote_addr (string) 346 remote_host (string) 347 server_name (string) 348 server_port (integer) 349 is_ssl (boolean) 350 num_headers (integer) 351 request_headers *(req_header_name req_header_value) 352 attributes *(attribut_name attribute_value) 353 request_terminator (byte) OxFF</pre></div> 354 <p>The <code>request_headers</code> have the following structure: 355 </p><div class="example"><pre>req_header_name := 356 sc_req_header_name | (string) [see below for how this is parsed] 357 358sc_req_header_name := 0xA0xx (integer) 359 360req_header_value := (string)</pre></div> 361 <p>The <code>attributes</code> are optional and have the following 362 structure:</p> 363 <div class="example"><pre>attribute_name := sc_a_name | (sc_a_req_attribute string) 364 365attribute_value := (string)</pre></div> 366 <p>Not that the all-important header is <code>content-length</code>, 367 because it determines whether or not the container looks for another 368 packet immediately.</p> 369 <h3>Detailed description of the elements of Forward Request 370 </h3> 371 <h3>Request prefix</h3> 372 <p>For all requests, this will be 2. See above for details on other Prefix 373 codes.</p> 374 375 <h3>Method</h3> 376 <p>The HTTP method, encoded as a single byte:</p> 377 <table> 378 <tr><td>Command Name</td><td>Code</td></tr> 379 <tr><td>OPTIONS</td><td>1</td></tr> 380 <tr><td>GET</td><td>2</td></tr> 381 <tr><td>HEAD</td><td>3</td></tr> 382 <tr><td>POST</td><td>4</td></tr> 383 <tr><td>PUT</td><td>5</td></tr> 384 <tr><td>DELETE</td><td>6</td></tr> 385 <tr><td>TRACE</td><td>7</td></tr> 386 <tr><td>PROPFIND</td><td>8</td></tr> 387 <tr><td>PROPPATCH</td><td>9</td></tr> 388 <tr><td>MKCOL</td><td>10</td></tr> 389 <tr><td>COPY</td><td>11</td></tr> 390 <tr><td>MOVE</td><td>12</td></tr> 391 <tr><td>LOCK</td><td>13</td></tr> 392 <tr><td>UNLOCK</td><td>14</td></tr> 393 <tr><td>ACL</td><td>15</td></tr> 394 <tr><td>REPORT</td><td>16</td></tr> 395 <tr><td>VERSION-CONTROL</td><td>17</td></tr> 396 <tr><td>CHECKIN</td><td>18</td></tr> 397 <tr><td>CHECKOUT</td><td>19</td></tr> 398 <tr><td>UNCHECKOUT</td><td>20</td></tr> 399 <tr><td>SEARCH</td><td>21</td></tr> 400 <tr><td>MKWORKSPACE</td><td>22</td></tr> 401 <tr><td>UPDATE</td><td>23</td></tr> 402 <tr><td>LABEL</td><td>24</td></tr> 403 <tr><td>MERGE</td><td>25</td></tr> 404 <tr><td>BASELINE_CONTROL</td><td>26</td></tr> 405 <tr><td>MKACTIVITY</td><td>27</td></tr> 406 </table> 407 <p>Later version of ajp13, will transport 408 additional methods, even if they are not in this list.</p> 409 410 <h3>protocol, req_uri, remote_addr, remote_host, server_name, 411 server_port, is_ssl</h3> 412 <p>These are all fairly self-explanatory. Each of these is required, and 413 will be sent for every request.</p> 414 415 <h3>Headers</h3> 416 <p>The structure of <code>request_headers</code> is the following: 417 First, the number of headers <code>num_headers</code> is encoded. 418 Then, a series of header name <code>req_header_name</code> / value 419 <code>req_header_value</code> pairs follows. 420 Common header names are encoded as integers, 421 to save space. If the header name is not in the list of basic headers, 422 it is encoded normally (as a string, with prefixed length). The list of 423 common headers <code>sc_req_header_name</code>and their codes 424 is as follows (all are case-sensitive):</p> 425 <table> 426 <tr><td>Name</td><td>Code value</td><td>Code name</td></tr> 427 <tr><td>accept</td><td>0xA001</td><td>SC_REQ_ACCEPT</td></tr> 428 <tr><td>accept-charset</td><td>0xA002</td><td>SC_REQ_ACCEPT_CHARSET 429 </td></tr> 430 <tr><td>accept-encoding</td><td>0xA003</td><td>SC_REQ_ACCEPT_ENCODING 431 </td></tr> 432 <tr><td>accept-language</td><td>0xA004</td><td>SC_REQ_ACCEPT_LANGUAGE 433 </td></tr> 434 <tr><td>authorization</td><td>0xA005</td><td>SC_REQ_AUTHORIZATION</td> 435 </tr> 436 <tr><td>connection</td><td>0xA006</td><td>SC_REQ_CONNECTION</td></tr> 437 <tr><td>content-type</td><td>0xA007</td><td>SC_REQ_CONTENT_TYPE</td> 438 </tr> 439 <tr><td>content-length</td><td>0xA008</td><td>SC_REQ_CONTENT_LENGTH</td> 440 </tr> 441 <tr><td>cookie</td><td>0xA009</td><td>SC_REQ_COOKIE</td></tr> 442 <tr><td>cookie2</td><td>0xA00A</td><td>SC_REQ_COOKIE2</td></tr> 443 <tr><td>host</td><td>0xA00B</td><td>SC_REQ_HOST</td></tr> 444 <tr><td>pragma</td><td>0xA00C</td><td>SC_REQ_PRAGMA</td></tr> 445 <tr><td>referer</td><td>0xA00D</td><td>SC_REQ_REFERER</td></tr> 446 <tr><td>user-agent</td><td>0xA00E</td><td>SC_REQ_USER_AGENT</td></tr> 447 </table> 448 <p>The Java code that reads this grabs the first two-byte integer and if 449 it sees an <code>'0xA0'</code> in the most significant 450 byte, it uses the integer in the second byte as an index into an array of 451 header names. If the first byte is not <code>0xA0</code>, it assumes that 452 the two-byte integer is the length of a string, which is then read in.</p> 453 <p>This works on the assumption that no header names will have length 454 greater than <code>0x9999 (==0xA000 - 1)</code>, which is perfectly 455 reasonable, though somewhat arbitrary.</p> 456 <div class="note"><h3>Note:</h3> 457 The <code>content-length</code> header is extremely 458 important. If it is present and non-zero, the container assumes that 459 the request has a body (a POST request, for example), and immediately 460 reads a separate packet off the input stream to get that body. 461 </div> 462 463 <h3>Attributes</h3> 464 <p>The attributes prefixed with a <code>?</code> 465 (e.g. <code>?context</code>) are all optional. For each, there is a 466 single byte code to indicate the type of attribute, and then its value 467 (string or integer). They can be sent in any order (though the C code 468 always sends them in the order listed below). A special terminating code 469 is sent to signal the end of the list of optional attributes. The list of 470 byte codes is:</p> 471 <table> 472 <tr><td>Information</td><td>Code Value</td><td>Type Of Value</td><td>Note</td></tr> 473 <tr><td>?context</td><td>0x01</td><td>-</td><td>Not currently implemented 474 </td></tr> 475 <tr><td>?servlet_path</td><td>0x02</td><td>-</td><td>Not currently implemented 476 </td></tr> 477 <tr><td>?remote_user</td><td>0x03</td><td>String</td><td /></tr> 478 <tr><td>?auth_type</td><td>0x04</td><td>String</td><td /></tr> 479 <tr><td>?query_string</td><td>0x05</td><td>String</td><td /></tr> 480 <tr><td>?jvm_route</td><td>0x06</td><td>String</td><td /></tr> 481 <tr><td>?ssl_cert</td><td>0x07</td><td>String</td><td /></tr> 482 <tr><td>?ssl_cipher</td><td>0x08</td><td>String</td><td /></tr> 483 <tr><td>?ssl_session</td><td>0x09</td><td>String</td><td /></tr> 484 <tr><td>?req_attribute</td><td>0x0A</td><td>String</td><td>Name (the name of the 485 attribute follows)</td></tr> 486 <tr><td>?ssl_key_size</td><td>0x0B</td><td>Integer</td><td /></tr> 487 <tr><td>are_done</td><td>0xFF</td><td>-</td><td>request_terminator</td></tr> 488 </table> 489 <p>The <code>context</code> and <code>servlet_path</code> are not 490 currently set by the C code, and most of the Java code completely ignores 491 whatever is sent over for those fields (and some of it will actually break 492 if a string is sent along after one of those codes). I don't know if this 493 is a bug or an unimplemented feature or just vestigial code, but it's 494 missing from both sides of the connection.</p> 495 <p>The <code>remote_user</code> and <code>auth_type</code> presumably 496 refer to HTTP-level authentication, and communicate the remote user's 497 username and the type of authentication used to establish their identity 498 (e.g. Basic, Digest).</p> 499 <p>The <code>query_string</code>, <code>ssl_cert</code>, 500 <code>ssl_cipher</code>, and <code>ssl_session</code> refer to the 501 corresponding pieces of HTTP and HTTPS.</p> 502 <p>The <code>jvm_route</code>, is used to support sticky 503 sessions -- associating a user's sesson with a particular Tomcat instance 504 in the presence of multiple, load-balancing servers.</p> 505 <p>Beyond this list of basic attributes, any number of other attributes 506 can be sent via the <code>req_attribute</code> code <code>0x0A</code>. 507 A pair of strings to represent the attribute name and value are sent 508 immediately after each instance of that code. Environment values are passed 509 in via this method.</p> 510 <p>Finally, after all the attributes have been sent, the attribute 511 terminator, <code>0xFF</code>, is sent. This signals both the end of the 512 list of attributes and also then end of the Request Packet.</p> 513 514</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 515<div class="section"> 516<h2><a name="resppacketstruct" id="resppacketstruct">Response Packet Structure</a></h2> 517 <p>for messages which the container can send back to the server.</p> 518 <div class="example"><pre>AJP13_SEND_BODY_CHUNK := 519 prefix_code 3 520 chunk_length (integer) 521 chunk *(byte) 522 chunk_terminator (byte) Ox00 523 524 525AJP13_SEND_HEADERS := 526 prefix_code 4 527 http_status_code (integer) 528 http_status_msg (string) 529 num_headers (integer) 530 response_headers *(res_header_name header_value) 531 532res_header_name := 533 sc_res_header_name | (string) [see below for how this is parsed] 534 535sc_res_header_name := 0xA0 (byte) 536 537header_value := (string) 538 539AJP13_END_RESPONSE := 540 prefix_code 5 541 reuse (boolean) 542 543 544AJP13_GET_BODY_CHUNK := 545 prefix_code 6 546 requested_length (integer)</pre></div> 547 <h3>Details:</h3> 548 <h3>Send Body Chunk</h3> 549 <p>The chunk is basically binary data, and is sent directly back to the 550 browser.</p> 551 552 <h3>Send Headers</h3> 553 <p>The status code and message are the usual HTTP things 554 (e.g. <code>200</code> and <code>OK</code>). The response header names are 555 encoded the same way the request header names are. See header_encoding above 556 for details about how the codes are distinguished from the strings.<br /> 557 The codes for common headers are:</p> 558 <table> 559 <tr><td>Name</td><td>Code value</td></tr> 560 <tr><td>Content-Type</td><td>0xA001</td></tr> 561 <tr><td>Content-Language</td><td>0xA002</td></tr> 562 <tr><td>Content-Length</td><td>0xA003</td></tr> 563 <tr><td>Date</td><td>0xA004</td></tr> 564 <tr><td>Last-Modified</td><td>0xA005</td></tr> 565 <tr><td>Location</td><td>0xA006</td></tr> 566 <tr><td>Set-Cookie</td><td>0xA007</td></tr> 567 <tr><td>Set-Cookie2</td><td>0xA008</td></tr> 568 <tr><td>Servlet-Engine</td><td>0xA009</td></tr> 569 <tr><td>Status</td><td>0xA00A</td></tr> 570 <tr><td>WWW-Authenticate</td><td>0xA00B</td></tr> 571 </table> 572 <p> After the code or the string header name, the header value is 573 immediately encoded.</p> 574 575 <h3>End Response</h3> 576 <p>Signals the end of this request-handling cycle. If the 577 <code>reuse</code> flag is true <code>(==1)</code>, this TCP connection can 578 now be used to handle new incoming requests. If <code>reuse</code> is false 579 (anything other than 1 in the actual C code), the connection should 580 be closed.</p> 581 582 <h3>Get Body Chunk</h3> 583 <p>The container asks for more data from the request (If the body was 584 too large to fit in the first packet sent over or when the request is 585 chunked). The server will send a body packet back with an amount of data 586 which is the minimum of the <code>request_length</code>, the maximum send 587 body size <code>(8186 (8 Kbytes - 6))</code>, and the number of bytes 588 actually left to send from the request body.<br /> 589 If there is no more data in the body (i.e. the servlet container is 590 trying to read past the end of the body), the server will send back an 591 <em>empty</em> packet, which is a body packet with a payload length of 0. 592 <code>(0x12,0x34,0x00,0x00)</code></p> 593 594</div> 595</div> 596<div class="bottomlang"> 597<p><span>Available Languages: </span><a href="/en/mod/mod_proxy_ajp.html" title="English"> en </a> | 598<a href="/fr/mod/mod_proxy_ajp.html" hreflang="fr" rel="alternate" title="Fran�ais"> fr </a> | 599<a href="/ja/mod/mod_proxy_ajp.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a></p> 600</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 again 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 Freenode, or sent to our <a href="http://httpd.apache.org/lists.html">mailing lists</a>.</div> 601<script type="text/javascript"><!--//--><![CDATA[//><!-- 602var comments_shortname = 'httpd'; 603var comments_identifier = 'http://httpd.apache.org/docs/2.4/mod/mod_proxy_ajp.html'; 604(function(w, d) { 605 if (w.location.hostname.toLowerCase() == "httpd.apache.org") { 606 d.write('<div id="comments_thread"><\/div>'); 607 var s = d.createElement('script'); 608 s.type = 'text/javascript'; 609 s.async = true; 610 s.src = 'https://comments.apache.org/show_comments.lua?site=' + comments_shortname + '&page=' + comments_identifier; 611 (d.getElementsByTagName('head')[0] || d.getElementsByTagName('body')[0]).appendChild(s); 612 } 613 else { 614 d.write('<div id="comments_thread">Comments are disabled for this page at the moment.<\/div>'); 615 } 616})(window, document); 617//--><!]]></script></div><div id="footer"> 618<p class="apache">Copyright 2014 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p> 619<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></div><script type="text/javascript"><!--//--><![CDATA[//><!-- 620if (typeof(prettyPrint) !== 'undefined') { 621 prettyPrint(); 622} 623//--><!]]></script> 624</body></html>
