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366 lines
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366 lines
14 KiB
HTML
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<title>Apache module mod_isapi</title>
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<!--#include virtual="header.html" -->
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<h1 align="CENTER">Module mod_isapi</h1>
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<p>This module supports ISAPI Extensions within Apache for
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Windows.</p>
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<p><a href="module-dict.html#Status"
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rel="Help"><strong>Status:</strong></a> Base<br />
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<a href="module-dict.html#SourceFile"
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rel="Help"><strong>Source File:</strong></a> mod_isapi.c<br />
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<a href="module-dict.html#ModuleIdentifier"
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rel="Help"><strong>Module Identifier:</strong></a>
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isapi_module<br />
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<a href="module-dict.html#Compatibility"
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rel="Help"><strong>Compatibility:</strong></a> WIN32 only</p>
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<h2>Summary</h2>
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<p>This module implements the Internet Server extension API. It
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allows Internet Server extensions (<em>e.g.</em> ISAPI .dll
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modules) to be served by Apache for Windows, subject to the
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noted restrictions.</p>
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<p>ISAPI extension modules (.dll files) are written by third
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parties. The Apache Group does not author these modules, so we
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provide no support for them. Please contact the ISAPI's author
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directly if you are experiencing problems running their ISAPI
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extention. <strong>Please <em>do not</em> post such problems to
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Apache's lists or bug reporting pages.</strong></p>
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<h2>Directives</h2>
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<ul>
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<li><a href="#isapifilecache">ISAPIFileCache</a></li>
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<li><a
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href="#isapireadaheadbuffer">ISAPIReadAheadBuffer</a></li>
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<li><a
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href="#isapilognotsupported">ISAPILogNotSupported</a></li>
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<li><a
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href="#isapiappendlogtoerrors">ISAPIAppendLogToErrors</a></li>
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<li><a
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href="#isapiappendlogtoquery">ISAPIAppendLogToQuery</a></li>
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</ul>
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<h2>Usage</h2>
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<p>In the server configuration file, use the AddHandler
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directive to associate ISAPI files with the
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<code>isapi-isa</code> handler, and map it to the with their
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file extensions. To enable any .dll file to be processed as an
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ISAPI extention, edit the httpd.conf file and add the following
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line:</p>
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<pre>
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AddHandler isapi-isa .dll
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</pre>
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<p>There is no capability within the Apache server to leave a
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requested module loaded. However, you may preload and keep a
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specific module loaded by using the following syntax in your
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httpd.conf:</p>
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<pre>
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ISAPICacheFile c:/WebWork/Scripts/ISAPI/mytest.dll
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</pre>
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<p>Whether or not you have preloaded an ISAPI extension, all
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ISAPI extensions are governed by the same permissions and
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restrictions as CGI scripts. That is, <code>Options
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ExecCGI</code> must be set for the directory that contains the
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ISAPI .dll file.</p>
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<p>Review the <a href="#notes">Additional Notes</a> and the <a
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href="#journal">Programmer's Journal</a> for additional details
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and clarification of the specific ISAPI support offered by
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mod_isapi.</p>
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<h2><a id="notes" name="notes">Additional Notes</a></h2>
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<p>Apache's ISAPI implementation conforms to all of the ISAPI
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2.0 specification, except for some "Microsoft-specific"
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extensions dealing with asynchronous I/O. Apache's I/O model
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does not allow asynchronous reading and writing in a manner
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that the ISAPI could access. If an ISA tries to access
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unsupported features, including async I/O, a message is placed
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in the error log to help with debugging. Since these messages
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can become a flood, the directive <code>ISAPILogNotSupported
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Off</code> exists to quiet this noise.</p>
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<p>Some servers, like Microsoft IIS, load the ISAPI extension
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into the server and keep it loaded until memory usage is too
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high, or unless configuration options are specified. Apache
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currently loads and unloads the ISAPI extension each time it is
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requested, unless the ISAPICacheFile directive is specified.
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This is inefficient, but Apache's memory model makes this the
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most effective method. Many ISAPI modules are subtly
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incompatible with the Apache server, and unloading these
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modules helps to ensure the stability of the server.</p>
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<p>Also, remember that while Apache supports ISAPI Extensions,
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it <strong>does not support ISAPI Filters.</strong> Support for
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filters may be added at a later date, but no support is planned
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at this time.</p>
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<h2><a id="journal" name="journal">Programmer's
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Journal</a></h2>
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<p>If you are programming Apache 2.0 mod_isapi modules, you
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must limit your calls to ServerSupportFunction to the following
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directives:</p>
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<dl>
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<dt>HSE_REQ_SEND_URL_REDIRECT_RESP</dt>
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<dd>Redirect the user to another location.<br />
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This must be a fully qualified URL (e.g.
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http://server/location).</dd>
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<dt>HSE_REQ_SEND_URL</dt>
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<dd>Redirect the user to another location.<br />
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This cannot be a fully qualified URL, you are not allowed to
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pass the protocol or a server name (e.g. simply
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/location).<br />
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This redirection is handled by the server, not the
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browser.<br />
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<strong>Warning:</strong> in their recent documentation,
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Microsoft appears to have abandoned the distinction between
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the two HSE_REQ_SEND_URL functions. Apache continues to treat
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them as two distinct functions with different requirements
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and behaviors.</dd>
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<dt>HSE_REQ_SEND_RESPONSE_HEADER</dt>
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<dd>Apache accepts a response body following the header if it
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follows the blank line (two consecutive newlines) in the
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headers string argument. This body cannot contain NULLs,
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since the headers argument is NULL terminated.</dd>
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<dt>HSE_REQ_DONE_WITH_SESSION</dt>
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<dd>Apache considers this a no-op, since the session will be
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finished when the ISAPI returns from processing.</dd>
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<dt>HSE_REQ_MAP_URL_TO_PATH</dt>
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<dd>Apache will translate a virtual name to a physical
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name.</dd>
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<dt>HSE_APPEND_LOG_PARAMETER</dt>
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<dd>
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This logged message may be captured in any of the following
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logs:
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<ul>
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<li>in the \"%{isapi-parameter}n\" component in a
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CustomLog directive</li>
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<li>in the %q log component with the
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ISAPIAppendLogToQuery On directive</li>
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<li>in the error log with the ISAPIAppendLogToErrors On
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directive</li>
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</ul>
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The first option, the %{isapi-parameter}n component, is
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always available and prefered.
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</dd>
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<dt>HSE_REQ_IS_KEEP_CONN</dt>
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<dd>Will return the negotiated Keep-Alive status.</dd>
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<dt>HSE_REQ_SEND_RESPONSE_HEADER_EX</dt>
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<dd>Will behave as documented, although the fKeepConn flag is
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ignored.</dd>
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<dt>HSE_REQ_IS_CONNECTED</dt>
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<dd>Will report false if the request has been aborted.</dd>
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</dl>
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<p>Apache returns FALSE to any unsupported call to
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ServerSupportFunction, and sets the GetLastError value to
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ERROR_INVALID_PARAMETER.</p>
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<p>ReadClient retrieves the request body exceeding the initial
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buffer (defined by ISAPIReadAheadBuffer). Based on the
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ISAPIReadAheadBuffer setting (number of bytes to buffer prior
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to calling the ISAPI handler) shorter requests are sent
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complete to the extension when it is invoked. If the request is
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longer, the ISAPI extension must use ReadClient to retrieve the
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remaining request body.</p>
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<p>WriteClient is supported, but only with the HSE_IO_SYNC flag
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or no option flag (value of 0). Any other WriteClient request
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will be rejected with a return value of FALSE, and a
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GetLastError value of ERROR_INVALID_PARAMETER.</p>
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<p>GetServerVariable is supported, although extended server
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variables do not exist (as defined by other servers.) All the
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usual Apache CGI environment variables are available from
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GetServerVariable, as well as the ALL_HTTP and ALL_RAW
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values.</p>
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<p>Apache 2.0 mod_isapi supports additional features introduced
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in later versions of the ISAPI specification, as well as
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limited emulation of async I/O and the TransmitFile semantics.
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Apache also supports preloading ISAPI .dlls for performance,
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neither of which were not available under Apache 1.3
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mod_isapi.</p>
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<hr />
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<h2><a id="isapifilecache" name="isapifilecache">ISAPIFileCache
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directive</a></h2>
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<!--%plaintext <?INDEX {\tt ISAPIFileCache} directive> -->
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<a href="directive-dict.html#Syntax"
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rel="Help"><strong>Syntax:</strong></a> ISAPIFileCache
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<em>file</em> [<em>file</em>] ...<br />
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<a href="directive-dict.html#Context"
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rel="Help"><strong>Context:</strong></a> server config<br />
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<a href="directive-dict.html#Override"
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rel="Help"><strong>Override:</strong></a> None<br />
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<a href="directive-dict.html#Status"
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rel="Help"><strong>Status:</strong></a> Base<br />
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<a href="directive-dict.html#Module"
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rel="Help"><strong>Module:</strong></a> mod_isapi<br />
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<a href="module-dict.html#Compatibility"
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rel="Help"><strong>Compatibility:</strong></a> Apache 2.0 and
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later, Win32 only
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<p>Specifies a space-separated list of file names to be loaded
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when the Apache server is launched, and remain loaded until the
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server is shut down. This directive may be repeated for every
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ISAPI .dll file desired. The full path name of each file should
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be specified.</p>
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<hr />
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<h2><a id="isapireadaheadbuffer"
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name="isapireadaheadbuffer">ISAPIReadAheadBuffer
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directive</a></h2>
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<!--%plaintext <?INDEX {\tt ISAPIReadAheadBuffer} directive> -->
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<a href="directive-dict.html#Syntax"
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rel="Help"><strong>Syntax:</strong></a> ISAPIReadAheadBuffer
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<em>size</em><br />
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<a href="directive-dict.html#Default"
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rel="Help"><strong>Default:</strong></a> 49152<br />
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<a href="directive-dict.html#Context"
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rel="Help"><strong>Context:</strong></a> server config<br />
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<a href="directive-dict.html#Override"
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rel="Help"><strong>Override:</strong></a> None<br />
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<a href="directive-dict.html#Status"
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rel="Help"><strong>Status:</strong></a> Base<br />
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<a href="directive-dict.html#Module"
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rel="Help"><strong>Module:</strong></a> mod_isapi<br />
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<a href="module-dict.html#Compatibility"
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rel="Help"><strong>Compatibility:</strong></a> Apache 1.3.13
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and later, Win32 only
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<p>Defines the maximum size of the Read Ahead Buffer sent to
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ISAPI extensions when they are initially invoked. All remaining
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data must be retrieved using the ReadClient callback; some
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ISAPI extensions may not support the ReadClient function. Refer
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questions to the ISAPI extension's author.</p>
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<hr />
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<h2><a id="isapilognotsupported"
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name="isapilognotsupported">ISAPILogNotSupported
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directive</a></h2>
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<!--%plaintext <?INDEX {\tt ISAPILogNotSupported} directive> -->
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<a href="directive-dict.html#Syntax"
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rel="Help"><strong>Syntax:</strong></a> ISAPILogNotSupported
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on|off<br />
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<a href="directive-dict.html#Default"
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rel="Help"><strong>Default:</strong></a> on<br />
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<a href="directive-dict.html#Context"
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rel="Help"><strong>Context:</strong></a> server config<br />
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<a href="directive-dict.html#Override"
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rel="Help"><strong>Override:</strong></a> None<br />
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<a href="directive-dict.html#Status"
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rel="Help"><strong>Status:</strong></a> Base<br />
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<a href="directive-dict.html#Module"
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rel="Help"><strong>Module:</strong></a> mod_isapi<br />
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<a href="module-dict.html#Compatibility"
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rel="Help"><strong>Compatibility:</strong></a> Apache 1.3.13
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and later, Win32 only
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<p>Logs all requests for unsupported features from ISAPI
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extensions in the server error log. While this should be turned
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off once all desired ISAPI modules are functioning, it defaults
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to on to help administrators track down problems.</p>
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<hr />
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<h2><a id="isapiappendlogtoerrors"
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name="isapiappendlogtoerrors">ISAPIAppendLogToErrors
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directive</a></h2>
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<!--%plaintext <?INDEX {\tt ISAPIAppendLogToErrors} directive> -->
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<a href="directive-dict.html#Syntax"
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rel="Help"><strong>Syntax:</strong></a> ISAPIAppendLogToErrors
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on|off<br />
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<a href="directive-dict.html#Default"
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rel="Help"><strong>Default:</strong></a> off<br />
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<a href="directive-dict.html#Context"
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rel="Help"><strong>Context:</strong></a> server config<br />
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<a href="directive-dict.html#Override"
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rel="Help"><strong>Override:</strong></a> None<br />
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<a href="directive-dict.html#Status"
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rel="Help"><strong>Status:</strong></a> Base<br />
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<a href="directive-dict.html#Module"
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rel="Help"><strong>Module:</strong></a> mod_isapi<br />
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<a href="module-dict.html#Compatibility"
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rel="Help"><strong>Compatibility:</strong></a> Apache 1.3.13
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and later, Win32 only
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<p>Record HSE_APPEND_LOG_PARAMETER requests from ISAPI
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extensions to the server error log.</p>
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<hr />
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<h2><a id="isapiappendlogtoquery"
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name="isapiappendlogtoquery">ISAPIAppendLogToQuery
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directive</a></h2>
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<!--%plaintext <?INDEX {\tt ISAPIAppendLogToQuery} directive> -->
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<a href="directive-dict.html#Syntax"
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rel="Help"><strong>Syntax:</strong></a> ISAPIAppendLogToQuery
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on|off<br />
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<a href="directive-dict.html#Default"
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rel="Help"><strong>Default:</strong></a> off<br />
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<a href="directive-dict.html#Context"
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rel="Help"><strong>Context:</strong></a> server config<br />
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<a href="directive-dict.html#Override"
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rel="Help"><strong>Override:</strong></a> None<br />
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<a href="directive-dict.html#Status"
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rel="Help"><strong>Status:</strong></a> Base<br />
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<a href="directive-dict.html#Module"
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rel="Help"><strong>Module:</strong></a> mod_isapi<br />
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<a href="module-dict.html#Compatibility"
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rel="Help"><strong>Compatibility:</strong></a> Apache 1.3.13
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and later, Win32 only
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<p>Record HSE_APPEND_LOG_PARAMETER requests from ISAPI
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extensions to the query field (appended to the CustomLog %q
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component).</p>
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<p><!--#include virtual="footer.html" -->
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</p>
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</body>
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</html>
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