diff options
Diffstat (limited to 'rubbos/app/tomcat-connectors-1.2.32-src/xdocs/ajp/ajpv13a.xml')
| -rw-r--r-- | rubbos/app/tomcat-connectors-1.2.32-src/xdocs/ajp/ajpv13a.xml | 698 |
1 files changed, 0 insertions, 698 deletions
diff --git a/rubbos/app/tomcat-connectors-1.2.32-src/xdocs/ajp/ajpv13a.xml b/rubbos/app/tomcat-connectors-1.2.32-src/xdocs/ajp/ajpv13a.xml deleted file mode 100644 index 3ab4502d..00000000 --- a/rubbos/app/tomcat-connectors-1.2.32-src/xdocs/ajp/ajpv13a.xml +++ /dev/null @@ -1,698 +0,0 @@ -<?xml version="1.0"?> -<!DOCTYPE document [ - <!ENTITY project SYSTEM "project.xml"> -]> -<document url="ajpv13a.html"> - - &project; - <copyright> - Licensed to the Apache Software Foundation (ASF) under one or more - contributor license agreements. See the NOTICE file distributed with - this work for additional information regarding copyright ownership. - The ASF licenses this file to You under the Apache License, Version 2.0 - (the "License"); you may not use this file except in compliance with - the License. You may obtain a copy of the License at - - http://www.apache.org/licenses/LICENSE-2.0 - - Unless required by applicable law or agreed to in writing, software - distributed under the License is distributed on an "AS IS" BASIS, - WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. - See the License for the specific language governing permissions and - limitations under the License. -</copyright> -<properties> -<title>AJPv13</title> -<author email="danmil@shore.net">danmil@shore.net</author> -<author email="jfrederic.clere@fujitsu-siemens.com">Jean-Frederic Clere</author> -<date>$Date: 2007-06-09 22:38:06 +0200 (Sat, 09 Jun 2007) $</date> -</properties> -<body> -<section name="Intro"> - -<p> -The original document was written by -Dan Milstein, <author email="danmil@shore.net">danmil@shore.net</author> -on December 2000. The present document is generated out of an xml file -to allow a more easy integration in the Tomcat documentation. - -</p> - -<p> -This describes the Apache JServ Protocol version 1.3 (hereafter -<b>ajp13</b>). There is, apparently, no current documentation of how the -protocol works. This document is an attempt to remedy that, in order to -make life easier for maintainers of JK, and for anyone who wants to -port the protocol somewhere (into jakarta 4.x, for example). -</p> - -</section> - -<section name="author"> - -<p> -I am not one of the designers of this protocol -- I believe that Gal -Shachor was the original designer. Everything in this document is derived -from the actual implementation I found in the tomcat 3.x code. I hope it -is useful, but I can't make any grand claims to perfect accuracy. I also -don't know why certain design decisions were made. Where I was able, I've -offered some possible justifications for certain choices, but those are -only my guesses. In general, the C code which Shachor wrote is very clean -and comprehensible (if almost totally undocumented). I've cleaned up the -Java code, and I think it's reasonably readable. -</p> -</section> - -<section name="Design Goals"> - -<p> -According to email from Gal Shachor to the jakarta-dev mailing list, -the original goals of <b>JK</b> (and thus <b>ajp13</b>) were to extend -<b>mod_jserv</b> and <b>ajp12</b> by (I am only including the goals which -relate to communication between the web server and the servlet container): - -<ul> - <li> Increasing performance (speed, specifically). </li> - - <li> Adding support for SSL, so that <code>isSecure()</code> and - <code>getScheme()</code> will function correctly within the servlet - container. The client certificates and cipher suite will be - available to servlets as request attributes. </li> - -</ul> -</p> -</section> - -<section name="Overview of the protocol"> - -<p> -The <b>ajp13</b> 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><p> -<ul> - <li> Idle <br/> No request is being handled over this connection. </li> - <li> Assigned <br/> The connecton is handling a specific request.</li> -</ul> - -</p><p> -Once a connection is assigned to handle a particular request, the basic -request informaton (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 (content-length > 0), 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: - -<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 tranfer).</li> - - <li>END_RESPONSE <br/> Finish the request-handling cycle.</li> -</ul> -</p><p> - -Each message is accompanied by a differently formatted packet of data. See -Response Packet Structures below for details. -</p> -</section> - -<section name="Basic Packet Structure"> - -<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> -Byte order: I am not clear about the endian-ness of the individual -bytes. I'm guessing the bytes are little-endian, because that's what XDR -specifies, and I'm guessing that sys/socket library is magically making -that so (on the C side). If anyone with a better knowledge of socket calls -can step in, that would be great. -</p><p> -There are four data types in the protocol: bytes, booleans, integers and -strings. - -<dl> - <dt><b>Byte</b></dt> - <dd>A single byte.</dd> - - <dt><b>Boolean</b></dt> - <dd>A single byte, 1 = true, 0 = false. Using other non-zero values as - true (i.e. C-style) may work in some places, but it won't in - others.</dd> - - <dt><b>Integer</b></dt> - <dd>A number in the range of 0 to 2^16 (32768). Stored in 2 bytes with - the high-order byte first.</dd> - - <dt><b>String</b></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 <b>not</b> 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. Note a size of -1 - (65535) indicates a null string and no data follow the length in this - case.</dd> -</dl> -</p> - -<subsection name="Packet Size"> -<p> -According to much of the code, the max packet -size is 8 * 1024 bytes (8K). The actual length of the packet is encoded in the -header. -</p> -</subsection> - -<subsection name="Packet Headers"> -<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. - - -<table> - <tr> - <th colspan="6">Packet Format (Server->Container)</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"><b>Packet Format (Container->Server)</b></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> -<p> -<A NAME="prefix-codes"></A> 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 (0x1234 and then length of the packet), but without -any prefix code after that (this seems like a mistake to me). -</p><p> -The web server can send the following messages to the servlet container: - -<table> - <tr> - <th>Code</th> - <th>Type of Packet</th> - <th>Meaning</th> - </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> -<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 immediatly after the <code>Forward Request</code> by the web server. -</p> - -<p>The servlet container can send the following types of messages to the web -server: -<table> - <tr> - <th>Code</th> - <th>Type of Packet</th> - <th>Meaning</th> - </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> -<p> -Each of the above messages has a different internal structure, detailed below. -</p> -</subsection> -</section> - -<section name="Request Packet Structure"> - -<p> -For messages from the server to the container of type "Forward Request": -</p><p> -<source> -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 -</source> -</p><p> -The <code>request_headers</code> have the following structure: -</p><p> -<source> -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) -</source> -</p><p> - -The <code>attributes</code> are optional and have the following structure: -</p><p> -<source> -attribute_name := sc_a_name | (sc_a_req_attribute string) - -attribute_value := (string) - -</source> -</p><p> -Not that the all-important header is "content-length', because it -determines whether or not the container looks for another packet -immediately. -</p><p> -Detailed description of the elements of Forward Request. -</p> -<subsection name="request_prefix"> -<p> -For all requests, this will be 2. -See above for details on other <A HREF="#prefix-codes">prefix codes</A>. -</p> -</subsection> - -<subsection name="method"> -<p> -The HTTP method, encoded as a single byte: -</p> - -<p> -<table> - <tr><th>Command Name</th><th>Code</th></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> - -<p>Later version of ajp13, when used with mod_jk2, will transport -additional methods, even if they are not in this list. -</p> - -</subsection> - -<subsection name="protocol, req_uri, remote_addr, remote_host, server_name, server_port, is_ssl"> -<p> - These are all fairly self-explanatory. Each of these is required, and - will be sent for every request. -</p> -</subsection> - -<subsection name="Headers"> -<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><p> -<table> - <tr><th>Name</th><th>Code value</th><th>Code name</th></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><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 '0xA0', 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 0x9999 (==0xA000 - 1), which is perfectly reasonable, though - somewhat arbitrary. (If you, like me, started to think about the cookie - spec here, and about how long headers can get, fear not -- this limit is - on header <b>names</b> not header <b>values</b>. It seems unlikely that - unmanageably huge header names will be showing up in the HTTP spec any time - soon). -</p><p> - <b>Note:</b> 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. -</p> -</subsection> - -<subsection name="Attributes"> -<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 a string to - give its value. They can be sent in any order (thogh 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><p> - -<table> - <tr><th>Information</th><th>Code Value</th><th>Note</th></tr> - <tr><td>?context</td><td>0x01</td><td>Not currently implemented</td></tr> - <tr><td>?servlet_path</td><td>0x02</td><td>Not currently implemented</td></tr> - <tr><td>?remote_user</td><td>0x03</td><td></td></tr> - <tr><td>?auth_type</td><td>0x04</td><td></td></tr> - <tr><td>?query_string</td><td>0x05</td><td></td></tr> - <tr><td>?route</td><td>0x06</td><td></td></tr> - <tr><td>?ssl_cert</td><td>0x07</td><td></td></tr> - <tr><td>?ssl_cipher</td><td>0x08</td><td></td></tr> - <tr><td>?ssl_session</td><td>0x09</td><td></td></tr> - <tr><td>?req_attribute</td><td>0x0A</td><td>Name (the name of the attribut follows)</td></tr> - <tr><td>?ssl_key_size</td><td>0x0B</td><td></td></tr> - <tr><td>?secret</td><td>0x0C</td><td></td></tr> - <tr><td>?stored_method</td><td>0x0D</td><td></td></tr> - <tr><td>are_done</td><td>0xFF</td><td>request_terminator</td></tr> -</table> - -</p><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). I'm not clear on why the password isn't also sent, but I don't - know HTTP authentication inside and out. -</p><p> - The <code>query_string</code>, <code>ssl_cert</code>, - <code>ssl_cipher</code>, and <code>ssl_session</code> refer to the - corresponding pieces of HTTP and HTTPS. -</p><p> - The <code>route</code>, as I understand it, is used to support sticky - sessions -- associating a user's sesson with a particular Tomcat instance - in the presence of multiple, load-balancing servers. I don't know the - details. -</p><p> - Beyond this list of basic attributes, any number of other attributes can - be sent via the <code>req_attribute</code> code (0x0A). 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, - 0xFF, is sent. This signals both the end of the list of attributes and - also then end of the Request Packet. -</p> -</subsection> - -</section> - -<section name="Response Packet Structure"> - -<p> -For messages which the container can send back to the server. - -<source> -AJP13_SEND_BODY_CHUNK := - prefix_code 3 - chunk_length (integer) - chunk *(byte) - - -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) -</source> - -</p> -<p> -Details: -</p> - -<subsection name="Send Body Chunk"> -<p> - The chunk is basically binary data, and is sent directly back to the browser. -</p> -</subsection> - -<subsection name="Send Headers"> -<p> - The status code and message are the usual HTTP things (e.g. "200" and "OK"). - The response header names are encoded the same way the request header names are. - See <A HREF="#header_encoding">above</A> for details about how the the - codes are distinguished from the strings. The codes for common headers are: -</p> - -<p> -<table> - <tr><th>Name</th><th>Code value</th></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> - -<p> - After the code or the string header name, the header value is immediately - encoded. -</p> - -</subsection> - -<subsection name="End Response"> -<p> - Signals the end of this request-handling cycle. If the - <code>reuse</code> flag is true (==1), this TCP connection can now be used to - handle new incoming requests. If <code>reuse</code> is false (anything - other than 1 in the actual C code), the connection should be closed. -</p> -</subsection> - -<subsection name="Get Body Chunk"> -<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 - chuncked). - 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 (8186 (8 Kbytes - 6)), 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 - "empty" packet, which is a body packet with a payload length of 0. - (0x12,0x34,0x00,0x00) -</p> -</subsection> -</section> - -<section name="Questions I Have"> - -<p> What happens if the request headers > max packet size? There is no -provision to send a second packet of request headers in case there are more -than 8K (I think this is correctly handled for response headers, though I'm -not certain). I don't know if there is a way to get more than 8K worth of -data into that initial set of request headers, but I'll bet there is -(combine long cookies with long ssl information and a lot of environment -variables, and you should hit 8K easily). I think the connector would just -fail before trying to send any headers in this case, but I'm not certain.</p> - -<p> What about authentication? There doesn't seem to be any authentication -of the connection between the web server and the container. This strikes -me as potentially dangerous.</p> - -</section> - -</body> -</document> |