update transformation

</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>

<div class="section">

<h2><a name="terms" id="terms">Filter Declarations, Providers and Chains</a></h2>

<img src="../images/mod_filter_old.gif" alt="" />

<p class="figure">

<img src="../images/mod_filter_old.gif" width="160" height="310" alt="[This image displays the traditional filter model]" /><br />

<dfn>Figure 1:</dfn> The traditional filter model</p>

<p>In the traditional model, output filters are a simple chain

from the content generator (handler) to the client.  This works well

provided the filter chain can be correctly configured, but presents

problems when the filters need to be configured dynamically based on

the outcome of the handler.</p>

<img src="../images/mod_filter_new.gif" alt="" />

<p class="figure">

<img src="../images/mod_filter_new.gif" width="423" height="331" alt="[This image shows the mod_filter model]" /><br />

<dfn>Figure 2:</dfn> The <code class="module"><a href="../mod/mod_filter.html">mod_filter</a></code> model</p>

<p>mod_filter works by introducing indirection into the filter

chain.  Instead of inserting filters in the chain, we insert

a filter harness which in turn dispatches conditionally

      <dt><code>HSE_REQ_SEND_URL_REDIRECT_RESP</code></dt>

      <dd>사용자를 다른 위치로 리다이렉션한다.<br />

      완전한 URL을 사용해야 한다 (<em>예를 들어,</em>

      <code>http://server/location</code>).</dd>.

      <code>http://server/location</code>).</dd>

      <dt><code>HSE_REQ_SEND_URL</code></dt>

      <dd>사용자를 다른 위치로 리다이렉션한다.<br />

    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>

    <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>

    </ul>

    <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).

    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:

    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.

    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>

    </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>

    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.

    integers and strings.</p>

    <dl>

    <dt><strong>Byte</strong></dt><dd>A single byte.</dd>

    <dt><strong>Boolean</strong></dt>

      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></p>

    </dl>

  <h3>Packet Size</h3>

    <p>According to much of the code, the max packet size is <code>

    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.

    code sets the maximum to be 8K.</p>

    <table>

      <tr>

        <td colspan="6"><em>Packet Format (Server-&gt;Container)</em></td>

        <td colspan="2">Data Length (n)</td>

        <td>Data</td>

      </tr>

    </table></p>

    </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>The web server can send the following messages to the servlet

     container:</p>

    <table>

      <tr>

        <td>Code</td>

        <td>Data</td>

        <td>Size (2 bytes) and corresponding body data.</td>

      </tr>

    </table></p>

    </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 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

    webserver:

    webserver:</p>

    <table>

      <tr>

        <td>Code</td>

        <td>CPong Reply</td>

        <td>The reply to a CPing request</td>

      </tr>

    </table></p>

    </table>

    <p>Each of the above messages has a different internal structure, detailed

    below.</p>

  <h3>Method</h3>

    <p>The HTTP method, encoded as a single byte:</p>

    <p><table>

    <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>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>

    </table>

    <p>Later version of ajp13, will transport 

    additional methods, even if they are not in this list.</p>

    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>

    <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

      <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>

    </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

    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>

    <table>

      <tr><td>Information</td><td>Code Value</td><td>Note</td></tr>

      <tr><td>?context</td><td>0x01</td><td>Not currently implemented

      </td></tr>

      attribute follows)</td></tr>

      <tr><td>?ssl_key_size</td><td>0x0B</td><td /></tr>

      <tr><td>are_done</td><td>0xFF</td><td>request_terminator</td></tr>

    </table></p>

    </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

    encoded the same way the request header names are. See header_encoding above

    for details about how the the codes are distinguished from the strings.<br />

    The codes for common headers are:</p>

    <p><table>

    <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>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>

    </table>

    <p> After the code or the string header name, the header value is

    immediately encoded.</p>

<table class="directive">

<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets some special options for the rewrite engine</td></tr>

<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>RewriteOptions <var>Options</var></code></td></tr>

<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>RewriteOptions MaxRedirects=10</code></td></tr>

<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>

<tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>

<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>

<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_rewrite</td></tr>

<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td><code>MaxRedirects</code> is available in Apache 2.0.45 and

<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td><code>MaxRedirects</code> is no longer available in version 2.1 and

later</td></tr>

</table>

      <p>The <code class="directive">RewriteOptions</code> directive sets some

      special options for the current per-server or per-directory

      configuration. The <em>Option</em> strings can be one of the

      following:</p>

      configuration. The <em>Option</em> string can be currently only one:</p>

      <dl>

      <dt><code>inherit</code></dt>

      server are inherited. In per-directory context this means

      that conditions and rules of the parent directory's

      <code>.htaccess</code> configuration are inherited.</dd>

      <dt><code>MaxRedirects=<var>number</var></code></dt>

      <dd>In order to prevent endless loops of internal redirects

      issued by per-directory <code class="directive"><a href="#rewriterule">RewriteRule</a></code>s, <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> aborts

      the request after reaching a maximum number of such redirects and

      responds with an 500 Internal Server Error. If you really need

      more internal redirects than 10 per request, you may increase

      the default to the desired value.</dd>

      </dl>

</div>

engine</td></tr>

<tr class="odd"><td><a href="mod_rewrite.html#rewritemap">RewriteMap <em>MapName</em> <em>MapType</em>:<em>MapSource</em>

</a></td><td></td><td>sv</td><td>E</td></tr><tr class="odd"><td class="descr" colspan="4">Defines a mapping function for key-lookup</td></tr>

<tr><td><a href="mod_rewrite.html#rewriteoptions">RewriteOptions <var>Options</var></a></td><td> MaxRedirects=10 </td><td>svdh</td><td>E</td></tr><tr><td class="descr" colspan="4">Sets some special options for the rewrite engine</td></tr>

<tr><td><a href="mod_rewrite.html#rewriteoptions">RewriteOptions <var>Options</var></a></td><td></td><td>svdh</td><td>E</td></tr><tr><td class="descr" colspan="4">Sets some special options for the rewrite engine</td></tr>

<tr class="odd"><td><a href="mod_rewrite.html#rewriterule">RewriteRule

      <em>Pattern</em> <em>Substitution</em></a></td><td></td><td>svdh</td><td>E</td></tr><tr class="odd"><td class="descr" colspan="4">Defines rules for the rewriting engine</td></tr>

<tr><td><a href="core.html#rlimitcpu">RLimitCPU <var>Sekunden</var>|max [<var>Sekunden</var>|max]</a></td><td></td><td>svdh</td><td>C</td></tr><tr><td class="descr" colspan="4">Begrenzt den CPU-Verbrauch von Prozessen, die von