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Apache官方在今天放出产品系列2.2的最新版本2.2.11的源码包 最流行的HTTP服务器软件之一

    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>0x9999 (==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>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>, and <code>ssl_session</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>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>(==1)</code>, 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>
  
  <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
    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 <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>
  
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