Add docs for mod_isapi

<dd>Server-parsed documents.

<dt><A HREF="mod_info.html">mod_info</a>

<dd>Server configuration information

<dt><A HREF="mod_isapi.html">mod_isapi</a>

<dd>Windows ISAPI Extension support

<dt><A HREF="mod_log_agent.html">mod_log_agent</A>

<dd>Logging of User Agents.

<dt><A HREF="mod_log_common.html">mod_log_common</A> up to Apache 1.1.1

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">

<HTML>

<HEAD>

<TITLE>Apache module mod_isapi</TITLE>

</HEAD>

<!-- Background white, links blue (unvisited), navy (visited), red (active) -->

<BODY

 BGCOLOR="#FFFFFF"

 TEXT="#000000"

 LINK="#0000FF"

 VLINK="#000080"

 ALINK="#FF0000"

>

<!--#include virtual="header.html" -->

<H1 ALIGN="CENTER">Module mod_isapi</h1>

<p>This module is contained in the <code>mod_isapi.c</code> file, and is

   compiled in by default. It provides support for ISAPI Extensions when

   running under Microsoft Windows. Any document with a handler of

   <code>isapi-isa</code> will be processed by this module.

<h2>Purpose</h2>

<p>This module implements the <a

   href="http://www.microsoft.com/win32dev/apiext/isapimrg.htm">ISAPI

   Extension</a> API. It allows Internet Server Applications (i.e., ISAPI

   Extensions) to be used with Apache for Windows.

<h2>Usage</h2>

<p>In the server configuration file, add a handler called

   <code>isapi-isa</code>, and map it to files with a <code>.DLL</code>

   extension. In other words:</p>

<pre>

    AddHandler isapi-isa dll

</pre>

<p>Now simply place the ISA DLLs into your document root, and they will

   be loaded when their URLs are accessed.</p>

<p>ISAPI Extensions are governed by the same restrictions as CGI

   scripts. That is, <code>Options ExecCGI</code> must be active in the

   directory that contains the ISA.</p>

<h2>Notes</h2>

<p>Apache's ISAPI implementation conforms to all of the ISAPI 2.0

   specification, except for the "Microsoft-specific" extensions dealing

   with ascynchronous I/O. Apache's I/O model does not allow asynchronous

   reading and writing in a manner that the ISAPI could access. If an ISA

   tries to access async I/O, a message will be place in the error log,

   to help with debugging.

<p>Some servers, like Microsoft IIS, load the ISA into the server, and

   keep it loaded until memory usage is too high, and it is

   unloaded. Apache currently loads and unloads the ISA for each

   request. This is inefficient, but Apache's request model makes this

   method the only method that currently works. A future release may use

   a more effective loading method.

<p>Apache 1.3a1 currently limits POST and PUT input to 48k per

   request. This is to work around a problem with the ISAPI implementation

   that could result in a denial of service attack. It is expected that

   support for larger uploads will be added soon.

<p>Also, remember that while Apache supports ISAPI Extensions, it does

   not support ISAPI Filters. Support for filters may be added at a later

   date, but no support is planned at this time.</p>

<!--#include virtual="footer.html" -->

</BODY>

</HTML>

<p>Configuring Apache is nearly identical to the Unix version of Apache,

   so most of the standard <a href="./">Apache documentation</a> is

   applicable. A few things are, however, different:</p>

   applicable. A few things are, however, different, or new:</p>

<ul>

  <li><p>Because Apache for Windows is multithreaded, it does not use a

</pre>

      <p>Information on <a href="mod/mod_dll.html#creating">creating module

         DLLs</a> is also available.</p>

  <li><p>Apache can also load ISAPI Extensions (i.e., Internet Server

         Applications), such as those used by Microsoft's IIS, and other

         Windows servers. <a href="mod/mod_isapi.html">More information

         is available.</a>

</ul>

<p>Once Apache is configured correctly, it is nearly ready to be